ROBUST PALLADIUM HYDRIDE CATALYST FOR ELECTROCATALYTIC FORMATE FORMATION WITH HIGH CO TOLERANCE
20230099785 · 2023-03-30
Assignee
Inventors
Cpc classification
Y02P20/133
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
C25B15/08
CHEMISTRY; METALLURGY
C10L1/02
CHEMISTRY; METALLURGY
C25B9/63
CHEMISTRY; METALLURGY
C25B11/054
CHEMISTRY; METALLURGY
International classification
C10L1/02
CHEMISTRY; METALLURGY
C25B15/08
CHEMISTRY; METALLURGY
Abstract
A supported catalyst for reducing CO.sub.2 is provided. The supported catalyst includes a plurality of support particles; and a plurality of catalyst particles disposed over each support particle. Characteristically, the catalyst particles has formula PdH.sub.x/C wherein x is 0.3 to 0.7. Methods for making the support particles and using the support particles to reduce carbon dioxide are also provided.
Claims
1. A supported catalyst comprising: a plurality of support particles; and a plurality of catalyst particles disposed over each support particle, the catalyst particles having formula PdH.sub.x/C wherein x is 0.3 to 0.7.
2. The supported catalyst of claim 1, wherein the catalyst particles have formula PdH.sub.0.5/C.
3. The supported catalyst of claim 1, wherein the support particles are carbon particles.
4. The supported catalyst of claim 1, wherein the catalyst particles have an average particle diameter of about 1 to 10 nm.
5. The supported catalyst of claim 1, wherein the catalyst particles have an average particle diameter of about 2.5 to 4 nm.
6. The supported catalyst of claim 1, wherein the supported catalyst has a faradaic efficiently greater than 90% for formate at −0.4 V (vs RHE) after 4 hours of initial operation.
7. The supported catalyst of claim 1, wherein the supported catalyst has a BET surface area from about 90 m.sup.2/g to 110 m.sup.2/g.
8. The supported catalyst of claim 1, wherein the supported catalyst has a BET surface area greater than 100 m.sup.2/g.
9. A method for forming catalysts for reducing CO.sub.2 supported on a substrate particle, the method comprising: a) dispersing support particles into an organic solvent; b) dissolving a palladium-containing compound into the organic solvent to form a first reaction mixture at a first temperature; c) adding one or more surfactants to the first reaction mixture to form a second reaction mixture at a second temperature; d) heating the second reaction mixture to a third temperature; and e) introducing a reducing agent into the second reaction mixture to form a third reaction mixture; f) heating the third reaction mixture to a fourth temperature to form a supported catalyst comprising: a plurality of support particles; and a plurality of catalyst particles disposed over each support particle, the catalyst particles having formula PdH.sub.x/C wherein x is 0.3 to 0.7.
10. The method of claim 9, wherein the catalyst particles having formula PdH.sub.0.5/C.
11. The method of claim 9, wherein the palladium-containing compound is Pd(acac).sub.2.
12. The method of claim 9, wherein the one or more surfactants are oleylamine and oleic acid.
13. The method of claim 9, wherein the reducing agent is LiBEt.sub.3H.
14. The method of claim 9, wherein the support particles are carbon particles.
15. The method of claim 9, wherein the catalyst particles have an average particle diameter of about 1 to 10 nm.
16. The method of claim 9, wherein the catalyst particles have an average particle diameter of about 2.5 to 4 nm.
17. The method of claim 9, wherein the supported catalyst has a BET surface area from about 90 m.sup.2/g to 110 m.sup.2/g.
18. The method of claim 9, wherein the supported catalyst has a BET surface area greater than 100 m.sup.2/g.
19. The method of claim 9, wherein the first temperature is about room temperature, the second temperature is greater than the first temperature, the third temperature is greater than the second temperature, and the fourth temperature is greater than the third temperature.
20. An electrochemical cell for reducing CO.sub.2 comprising: an electrochemical cell chamber partitioned into a working compartment and a counter compartment; an ionomeric membrane separating the working compartment and the counter compartment; an electrolyte disposed in the working compartment and the counter compartment; a working electrode positioned in the working compartment, the working electrode comprising: an electrode support; a supported catalyst dispersed over a surface of the electrode support, the supported catalyst including: a plurality of support particles; and a plurality of catalyst particles disposed over each support particle, the catalyst particles having formula PdH.sub.x/C wherein x is 0.3 to 0.7; and a counter electrode disposed in the counter compartment; a CO.sub.2 source that introduces CO.sub.2 into the working compartment; and a voltage source configured to negatively bias the working electrode with respect to the counter electrode such that CO.sub.2 is reduced to formate.
21. The electrochemical cell of claim 20, wherein the catalyst particles having formula PdH.sub.0.5/C.
22. The electrochemical cell of claim 20, wherein the electrode support is electrically conductive.
23. The electrochemical cell of claim 22, wherein the electrode support is composed of carbon.
24. The electrochemical cell of claim 20 further comprising a reference electrode.
25. The electrochemical cell of claim 24, wherein the voltage source is a potentiostat.
26. A method for reducing CO.sub.2, the method comprising: introducing CO.sub.2 into the working compartment of the electrochemical cell of claim 20; and negatively biasing the working electrode with respect to the counter electrode such that CO.sub.2 is reduced to formate.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
[0018] For a further understanding of the nature, objects, and advantages of the present disclosure, reference should be made to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:
[0019]
[0020]
[0021]
[0022]
[0023]
[0024]
[0025]
[0026]
[0027]
[0028]
[0029]
[0030]
[0031]
[0032]
[0033]
[0034]
[0035]
[0036]
[0037]
DETAILED DESCRIPTION
[0038] Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present invention, which constitute the best modes of practicing the invention presently known to the inventors. The Figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the invention and/or as a representative basis for teaching one skilled in the art to variously employ the present invention.
[0039] Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: percent, “parts of,” and ratio values are by weight; the term “polymer” includes “oligomer,” “copolymer,” “terpolymer,” and the like; molecular weights provided for any polymers refers to weight average molecular weight unless otherwise indicated; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.
[0040] It must also be noted that, as used in the specification and the appended claims, the singular form “a,” “an,” and “the” comprise plural referents unless the context clearly indicates otherwise. For example, reference to a component in the singular is intended to comprise a plurality of components.
[0041] As used herein, the term “about” means that the amount or value in question may be the specific value designated or some other value in its neighborhood. Generally, the term “about” denoting a certain value is intended to denote a range within +/−5% of the value. As one example, the phrase “about 100” denotes a range of 100+/−5, i.e., the range from 95 to 105. Generally, when the term “about” is used, it can be expected that similar results or effects according to the invention can be obtained within a range of +/−5% of the indicated value.
[0042] As used herein, the term “and/or” means that either all or only one of the elements of said group may be present. For example, “A and/or B” shall mean “only A, or only B, or both A and B.” In the case of “only A”, the term also covers the possibility that B is absent, i.e., “only A, but not B.”
[0043] It is also to be understood that this invention is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present invention and is not intended to be limiting in any way.
[0044] The term “comprising” is synonymous with “including,” “having,” “containing,” or “characterized by.” These terms are inclusive and open-ended and do not exclude additional, unrecited elements or method steps.
[0045] The phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. When this phrase appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.
[0046] The phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.
[0047] The phrase “composed of” means “including” or “consisting of” Typically, this phrase is used to denote that an object is formed from a material.
[0048] With respect to the terms “comprising,” “consisting of,” and “consisting essentially of,” where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms.
[0049] The term “one or more” means “at least one” and the term “at least one” means “one or more.” The terms “one or more” and “at least one” include “plurality” and “multiple” as a subset. In a refinement, “one or more” includes “two or more.”
[0050] The term “substantially,” “generally,” or “about” may be used herein to describe disclosed or claimed embodiments. The term “substantially” may modify a value or relative characteristic disclosed or claimed in the present disclosure. In such instances, “substantially” may signify that the value or relative characteristic it modifies is within ±0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% or 10% of the value or relative characteristic.
[0051] It should also be appreciated that integer ranges explicitly include all intervening integers. For example, the integer range 1-10 explicitly includes 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Similarly, the range 1 to 100 includes 1, 2, 3, 4 . . . 97, 98, 99, 100. Similarly, when any range is called for, intervening numbers that are increments of the difference between the upper limit and the lower limit divided by 10 can be taken as alternative upper or lower limits. For example, if the range is 1.1. to 2.1 the following numbers 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 can be selected as lower or upper limits.
[0052] When referring to a numeral quantity, in a refinement, the term “less than” includes a lower non-included limit that is 5 percent of the number indicated after “less than.” For example, “less than 20” includes a lower non-included limit of 1 in a refinement. Therefore, this refinement of “less than 20” includes a range between 1 and 20. In another refinement, the term “less than” includes a lower non-included limit that is, in increasing order of preference, 20 percent, 10 percent, 5 percent, or 1 percent of the number indicated after “less than.”
[0053] In the examples set forth herein, concentrations, temperature, and reaction conditions (e.g., pressure, pH, flow rates, etc.) can be practiced with plus or minus 50 percent of the values indicated rounded to or truncated to two significant figures of the value provided in the examples. In a refinement, concentrations, temperature, and reaction conditions (e.g., pressure, pH, flow rates, etc.) can be practiced with plus or minus 30 percent of the values indicated rounded to or truncated to two significant figures of the value provided in the examples. In another refinement, concentrations, temperature, and reaction conditions (e.g., pressure, pH, flow rates, etc.) can be practiced with plus or minus 10 percent of the values indicated rounded to or truncated to two significant figures of the value provided in the examples.
[0054] For all compounds expressed as an empirical chemical formula with a plurality of letters and numeric subscripts (e.g., CH.sub.2O), values of the subscripts can be plus or minus 50 percent of the values indicated rounded to or truncated to two significant figures. For example, if CH.sub.2O is indicated, a compound of formula C.sub.(0.8-1.2)H.sub.(1.6-2.4)O.sub.(0.8-1.2). In a refinement, values of the subscripts can be plus or minus 30 percent of the values indicated rounded to or truncated to two significant figures. In still another refinement, values of the subscripts can be plus or minus 20 percent of the values indicated rounded to or truncated to two significant figures.
Abbreviations
[0055] “CO.sub.2RR” means carbon dioxide reduction reaction.
[0056] “FE” means faradaic efficiency.
[0057] “LSV” means linear sweep voltammetry.
[0058] In at least one aspect, the present invention is related to the electrochemical reduction of CO.sub.2. Electrochemical reduction of CO.sub.2 to formic acid is of great significance to renewable chemical synthesis and green energy storage. Palladium stands out from many potential electrocatalysts because of its unique capability of producing formate at low overpotential or even near-equilibrium potential. Inevitably produced CO, however, poisons and deactivates the surface of Pd, resulting in an insufficient operating life-time for conventional and even optimized Pd catalysts. Herein, we present a hydro-gen-rich Palladium Hydride catalyst (PdH.sub.0.5/C) derived from a one-step solvothermal synthesis. This catalyst showed a 93.1% faradaic efficiency for formate at −0.4 V (vs RHE). The working lifetime reached a record of 4 hours, which was ˜15 times longer than a commercial Pd catalyst and outperforming all previously reported Pd-based catalysts in electrosynthesis of formate from CO.sub.2. The high CO tolerance was attributed to the high selectivity towards formate with the presence of lattice hydrogen and the relatively weak CO adsorption strength on diverse active sites (i.e. kink, step, and terrace) of our catalyst. Isotopic analysis revealed a direct participation of lattice hydrogen in the protonation of the carbon atoms during formate formation. A detailed mechanism of the hydrogen transformation was proposed for both hydride and pure Pd catalysts.
[0059] With reference to
[0060] In some variations, the supported catalyst advantageously has a faradaic efficiently greater than 90% for formate at −0.4 V (vs. RHE) after 4 hours of initial operation. In some refinements, the supported catalyst advantageously has a faradaic efficiently greater than 80%, 85%, 90%, or 95% for formate at −0.4 V (vs. RHE) after 4 hours of initial operation
[0061] In another variation, the supported catalyst has a BET surface area from about 90 m.sup.2/g to 110 m.sup.2/g. In some refinements, the supported catalyst has a BET surface area of at least 75 m.sup.2/g, 80 m.sup.2/g, 85 m.sup.2/g, 90 m.sup.2/g, 95 m.sup.2/g, or 100 m.sup.2/g. In further refinements, the supported catalyst has a BET surface area of at least 150 m.sup.2/g, 130 m.sup.2/g, 125 m.sup.2/g, 120 m.sup.2/g, 110 m.sup.2/g, or 110 m.sup.2/g. In a refinement, the supported catalyst has a BET surface area greater than 100 m.sup.2/g.
[0062] Referring to
[0063] Typically, electrode support 38 is electrically conductive. In a refinement, the electrode support is composed of carbon.
[0064] Still referring to
[0065] In another embodiment, a method for reducing CO.sub.2 using the electrochemical cell of
[0066] In another embodiment, a method for forming the catalysts supported on substrate particles of
[0067] In step d), the second reaction mixture is heated to a third temperature, and then in step e), a reducing agent (e.g. LiBEt.sub.3H) is introduced into the second reaction mixture to form a third reaction mixture. The third reaction mixture is heated to a fourth temperature to form a supported catalyst comprising a plurality of support particles; and a plurality of catalyst particles disposed over each support particle, the catalyst particles having formula PdH.sub.x/C wherein x is 0.3 to 0.7. In some refinements, x is at least 0.1, 0.2, 0.3, 0.4, 0.45, or 0.48 and at most least 0.9, 0.8, 0.7, 0.6, 0.55, or 0.52. In a refinement, catalyst particles 14 are described by formula PdH.sub.0.5/C. Typically, the catalyst particles have an average particle diameter of about 1 to 10 nm. In a refinement, the catalyst particles have an average particle diameter of about 2.5 to 4 nm with an average of about 3.15. Typically, the first temperature is about room temperature (e.g., 20 to 25° C.), the second temperature (e.g., 80 to 120° C.) is greater than the first temperature, the third temperature (e.g., 130 to 170° C.) is greater than the second temperature, and the fourth temperature (e.g., 180 to 230° C.) is greater than the third temperature.
[0068] Typically, the palladium-containing compound is Pd(acac).sub.2 and the surfactants are oleylamine and oleic acid. As set forth above, the support particles are carbon particles.
[0069] The following examples illustrate the various embodiments of the present invention. Those skilled in the art will recognize many variations that are within the spirit of the present invention and scope of the claims.
1. Experimental Section
1.1. Chemicals
[0070] Palladium (II) acetylacetonate (Pd(acac).sub.2, 99%, Sigma Aldrich), Benzyl ether ((C.sub.6H.sub.5CH.sub.2).sub.2O, 98%, Sigma Aldrich), Oleylamine (70%, Sigma Aldrich), Oleic acid (≥99%, Sigma Aldrich), LiBEt3H (Li(C2H5)3BH, 1.0 M lithium triethylborohydride in THF), Potassium bicarbonate (KHCO.sub.3, 99.97%, Sigma Aldrich), Potassium carbonate (K2CO.sub.3, 99.995%, Sigma Aldrich), Deuterium oxide (D.sub.2O, 99.9%, Sigma Aldrich), 3-(Trimethylsilyl)-1-propanesulfonic acid sodium salt (DSS, 97%, Sigma Aldrich), AvCarb MGL190 (Fuel Cell Store).
1.2. Catalyst Synthesis
[0071] The PdH.sub.0.5/C (20 wt % Pd) catalysts were synthesized through one-step solvothermal synthesis technique as shown in
1.3. Material Characterization
[0072] Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the composition of PdH.sub.0.5/C catalyst. Aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy (EDS) was performed using a JEOL Grand ARM300F were employed to characterize the morphology, lattice constant, and elemental distribution in the PdH.sub.0.5/C catalyst. Transmission electron microscopy images were acquired using a JEOL JEM-2800. The surface electronic structures were analyzed using X-ray photoelectron spectroscopy (XPS) from AXIS Supra by Kratos Analytical. The binding energies were calibrated with respect to the C is peak at 285 eV. Crystalline structures and hydride content of catalysts were determined using powder X-ray diffraction (XRD). Temperature programmed desorption (TPD) in Ar environment was employed to help to identify the hydride content in catalysts. The specific surface area of catalysts was measured using Brunauer-Emmett-Teller (BET) theory.
1.4. Electrochemical Measurements
[0073] Electrochemical reduction of CO.sub.2 was conducted in a glass H-cell with a three-electrode system at room temperature. Counter and working compartments were separated by a Nafion 117 membrane, containing 20 mL and 30 mL of 0.1 M KHCO.sub.3 electrolyte (made with Millipore water), respectively. A carbon rod and an Ag/AgCl (3 M KCl, BASi) served as the counter electrode and the reference electrode, respectively. A hand-cut carbon paper (AvCarb MGL190) with a surface area of 1 cm.sup.2 was prepared as a working electrode. Carbon paper was pretreated with plasma and acid washing to modify the surface to be hydrophilic. Catalyst ink was prepared by dispersing 2.5 mg of Pd/C in 960 μL of isopropanol and 40 μL of 5 wt % Nafion isopropanol solutions with ultrasonication for 30 min. 100 μL of well-mixed ink was drop-casted onto the pretreated carbon paper electrode to meet a Pd loading of 50 μg/cm.sup.2, followed by drying in a vacuum oven at 60° C. overnight. CO.sub.2 was purged to both counter and working electrolyte with 30 sccm for 30 min until saturation prior to all electrochemical experiments. CO.sub.2 was then continually bubbled into the electrolyte with 30 sccm during all electrochemical experiments for continuous saturation.
[0074] The CO stripping method was used to analyze the affinity of CO on the Pd-based catalyst electrode as Pd readily adsorb CO. A monolayer of CO adsorbed on the Pd surface by purging CO into the 0.1 M HClO.sub.4 solution for 10 min while holding the potential at 0.05V (vs RHE), followed by introducing Ar for 10 min to passivate the surface and remove superfluous CO in the system. The monolayer of CO already deposited on the surface of Pd is then electrochemically oxidized by sweeping potential from 0.05V to 1.5V at a scan rate of 5 mV/s. The total charge of CO oxidation can be derived by integrating the area between peak curve and baseline, in which the baseline is obtained from CV in Ar-saturated 0.1 M HClO.sub.4 with the same scan rate. Electrochemically active surface area (ECSA) can be calculated by dividing the charge by the conversion factor (420 μC/cm.sup.2).
1.5. Product Quantification
[0075] The liquid products derived from electrolysis at constant potentials for 1 hour in the 0.1 M KHCO.sub.3 electrolyte were quantified by a Bruker CRYO 500 MHz nuclear magnetic resonance (NMR) spectroscopy instrument. Deuterium oxide (D.sub.2O) and 3-(trimethylsilyl)-1-propanesulfonic acid sodium salt (DSS) were used as locking solvent and internal standard, respectively. The NMR test sample was the mixture of 500 μL of post-electrolysis electrolyte, 100 μL of D.sub.2O, and 100 μL of 6 mM DSS (made with Millipore water). A solvent suppression method was applied to restrain the signal from H.sub.2O for better accuracy. The .sup.1H-NMR spectrum was processed and analyzed on Topspin 4.0.8 software.
[0076] The faradaic efficiency (FE) of products from CO.sub.2 reduction was calculated from the following equation:
FE=ZFVC/Q×100%
where Z is the number of electrons transferred to obtain 1 molecule of a specific product such as 2 for formate, F is the Faraday's constant (96485 C/mol), V is the total volume of catholyte in L, C is the concentration of catholyte measured from NMR analysis in mol/L. Q is the total charge passed during the bulk electrolysis in C.
2. Results and Discussion
2.1. Formation and Structure of Ultrafine Pd—H.SUB.0.5 .Nanoparticles
[0077]
[0078]
[0079] X-ray photoelectron spectroscopy (XPS) was carried out to determine the oxidation state of PdH0.5/C. The XPS spectra of Pd 3d peak region for PdH.sub.0.5/C and commercial Pd/C are presented in
[0080] The crystal structure of PdH.sub.0.5/C, commercial Pd/C, and commercial Pd/C (H.sub.2) is determined by powder XRD as shown in
[0081]
2.2. Electrochemical HCOO Formation
[0082] Cathodic linear sweep voltammetry (LSV) is recorded at 5 mV/s for PdH.sub.0.5/C and commercial Pd/C casted on a carbon paper electrode in Ar- and CO.sub.2-saturated 0.1 M KHCO.sub.3 electrolyte as shown in
2.3. Stability and CO Tolerance
[0083] To assess the CO poisoning process, CO gas was artificially introduced into the system in the middle of CO.sub.2 reduction process..sup.55 As shown in
[0084] CO stripping was employed to further investigate the CO affinity on PdH.sub.0.5/C catalyst. As shown in
[0085] Long duration CO.sub.2RR stability tests for PdH.sub.0.5/C and commercial Pd/C in CO.sub.2-saturated 0.1 M KHCO.sub.3 at −0.4V are shown in
TABLE-US-00001 TABLE 1 Comparison with reported Pd based electrocatalysts FEHC jtotal jHCOO- Loading E Durability OO- (mA/cm (mA/cm (μgPd/cm Catalyst (V) (min) (%) 2) 2) 2) Ref Pd/Ti −0.35 20 95% 5.5 5.23 50 2015 commercial 160 30% 1.2 0.36 Kanan Pd70Pt30/C −0.4 10 79% 5.8 4.6 73 2015 120 58% 3.6 2.07 Marc Koper Pd −0.2 0 -- 22 -- 83,333** 2016 high index 60 97% 20 19.4 Sargent Pd/C −0.3 2 -- 25 -- 50 2017 10 95% 1 0.95 Xinhe Bao Pd-B/C −0.5 30 80% 4.5 3.6 100 2018 300 55% 3.5 1.93 Wen-Bin Cai Pd/C −0.425 0 -- 16 -- 85.7 2019 4 75% 1.5 1.13 Joshua Snyder PdH0.5/C −0.4 60 93% 3.7 3.44 50 ours 120 93% 3.2 2.97 180 91% 2.2 2 240 90% 0.4 0.36 330 70% 0.25 0.18 **High or surplus Pd loadings result in a diffusion limited formate formation, wherein the CO poisoning gradually takes place on unused Pd surface. This electrode set-up could show stable current and even FE before all extra Pd functionalizes. Please see Figure S8 for a CA test on electrode with 4-fold Pd loading.
[0086] The TEM images and XPS spectrum (
[0087] A cycling performance study was performed to measure the recovery capability of a single PdH.sub.0.5/C electrode from CO poisoning in multiple cycles. Two methods are employed to remove the surface covered CO: exposing the electrode to air or applying a positive potential shock between each cycle. As shown in
2.4. The Role of Lattice Hydrogen and its Participation Pathway Towards HCOO-
[0088] From the literature, DTF calculation has been employed to explain the mechanism of CO.sub.2RR on Pd catalysts. It's generally accepted that *COOH is favored on bare Pd.82 A higher free energy for *COOH is observed on Pd with more hydride82, and *OCHO is formed far easier than *COOH75, indicating formate formation is favored on PdH. Formate becomes the predominant product of CO.sub.2RR on the Pd surface with full hydride coverage.75 Besides, hydride and *CO exhibit interdependent and interactive behavior. Hydride weakens *CO adsorption75,77,82, hampering CO poisoning and promoting the formation of formate. Similar results have been shown in the work of Kersten et al. using microkinetic models that α-PdH is poisoned by CO, while β-PdH isn't..sup.111 *CO can also restrict hydride in turn, that the more *CO, the less hydride will be on the surface, resulting in more *CO adsorption.sup.79, which could be the explanation of the accelerating decreasing of current density observed in the stability test on our PdH.sub.0.5/C (
[0089] To elucidate the reaction pathway towards HCOO- formation on PdH.sub.0.5/C, the role of lattice hydrogen and surface adsorbed H* species were studied via isotopic analysis, wherein D.sub.2O (deuterium oxide) and K.sub.2CO.sub.3 were used to provide a protium (.sup.1H or hydrogen-1) free environment. The .sup.1H-NMR employed here was able to quantitatively detect the produced HCOO- molecules, but was blind to the DCOO.sup.− counterparts. As shown in Table 2, after a 12-minute CA at −0.4 V in 0.1 M K.sub.2CO.sub.4 electrolyte, the commercial Pd/C catalysts produced 5.76 μmol HCOO- in H.sub.2O and non-detectable HCOO- in D.sub.2O. In the D.sub.2O system, the potential external .sup.1H contamination from Nafion ionomer was calculated at 1.42×10.sup.−6 μmol HCOO-, assuming a rapid proton exchange between the Nafion ionomer (0.813 μmol .sup.1H) and bulk D.sub.2O (30 mL, 3.3×10.sup.6 μmol .sup.2H). The zero HCOO.sup.− formation in D.sub.2O system further confirmed the negligible .sup.1H contamination from Nafion and other cell components.
TABLE-US-00002 TABLE 2 Evaluation of lattice hydrogen participation by isotopic analysis with D.sub.2O and K.sub.2CO.sub.3. Loading Yield.sub.HCOO—* Yield.sub.HCOO—** Assumed Catalyst μg.sub.Pd cm.sup.−2 Solvent μmol μmol pathway** Pd/C 50 H.sub.2O 5.76 — — commercial D.sub.2O ~0 1.42 × 10.sup.−6 Nafion contamination PdH.sub.0.5/C 50 H.sub.2O 117 — — D.sub.2O 6.74 × 10.sup.−6 *** H.sub.Pd—H.fwdarw.H.sup.+.sub.aq.fwdarw.HCOOH 0.2075 0.103 H.sub.Pd—H.fwdarw.HCOOH 0.206 H.sub.Pd—H.fwdarw.HCOOD 100 D.sub.2O 0.4139 0.412 H.sub.Pd—H.fwdarw.HCOOD 200 D.sub.2O 0.8513 0.824 H.sub.Pd—H.fwdarw.HCOOD *Actual HCOO— yield detected by .sup.1H-NMR **Theoretical yield by assumed reaction pathway of lattice hydrogen in Pd—H HPd—H.fwdarw.H + aq.fwdarw.HCOOH, all lattice hydrogen leached out into the D.sub.2O electrolyte and then participated in the reaction for formate HPd—H.fwdarw.HCOOH, lattice hydrogen directly protonate both carbon and oxygen atoms in formate HPd—H.fwdarw.HCOOD, lattice hydrogen only directly protonate the carbon atom ‘Nafion contamination only ‘the Nafion ionomer were assumed to rapidly exchange protons with bulk D.sub.2O right after being immersed into the electrolyte. *** Calculation considering the ratio of lattice hydrogen and D.sub.2O and the formate yield in H.sub.2O
[0090] When using PdH.sub.0.5/C catalysts, the cathodic current carried at −0.4V v. s. RHE gradually dropped to zero in ˜70 min in K.sub.2CO.sub.3+H.sub.2O system (
*+[e.sup.−+H.sup.+(aq)].fwdarw.*H (5)
*H.sup.+C0.sub.2.fwdarw.*HCOO (6)
*HCOO+[e.sup.−+H.sup.+(aq)].fwdarw.*+HCOOH (7)
[0091] As mentioned before, the hydrogen content in PdH.sub.0.5/C was well maintained in the 4-hour CA (
[0092] In contrast, pure Pd nanoparticles rely on the dynamic surface hydride formed at cathodic conditions..sup.88 Kanan and co-workers suggested the formation of β-hydride (Pd—H.sub.x, x˜0.7) on the commercial Pd surface, based on an early work for the electrochemical Pd hydride formation in a non-CO.sub.2RR environment..sup.115 In fact, the nature of pure Pd nanoparticles in electrolysis remains ambiguous. In our opinion, the Pd nanoparticles in CO.sub.2RR tend to form a dynamic hydride surface that is closed to a-phase..sup.116 The core of the Pd particles, particularly the big ones, remains as a pure Pd phase or hydrogen-poor phase. Consequently, the surface H* species have chemical potentials for HCOO- formation as well as diffusing into the bulk Pd. Therefore, the protonation of the CO.sub.2 molecule or associated intermediates is not as favorable as the PdH.sub.0.5/C catalysts. This explains their undermined stability and FE as shown in Table 1.
[0093] Looking beyond the CO tolerance improvement by lattice hydrogen, the design of CO-immune Pd-based electrocatalysts can realize an energy-efficient HCOO- production in real. Another interesting finding in this work is the 6.5% sub-peak in CO stripping (
2. Conclusions
[0094] In summary, we synthesized hydrogen-rich PdH.sub.0.5 nanoparticles with an average size of 3.15 nm monodispersed onto carbon black by using an undemanding solvothermal synthesis method. The existence of hydride in the Pd lattice remarkably expands the window of CO.sub.2RR and ameliorates the electrocatalytic CO.sub.2 reduction activity as well as stability by modifying the surface electronic structure and participating in the electrohydrogenation of CO.sub.2, exhibiting a 93.1% faradaic efficiency of formate for the 1st hour and remained above 90% faradaic efficiency of formate for 4 hours of CO.sub.2 electroreduction in 0.1 M KHCO.sub.3 at −0.4V, which stability is over 15 times better than commercial Pd/C. The TEM and XPS results of PdH.sub.0.5/C electrode before and after the stability test indicate the constant lattice parameter during CO.sub.2RR, bespeaking the significant role of hydride in electrolysis. CO poisoning occupies and deactivates the active catalytic surface, where step and kink sites on the nanoparticle surface of PdH.sub.0.5/C are found to bind CO weaker than the terrace site, triggering the high CO tolerance and superb CO.sub.2 reduction stability. The plateau current density after the stability test matches the kink or grain boundaries site ratio compared to initial current density with formate continuously produced, suggesting a potential immune site for CO poisoning on PdH.sub.0.5/C. Cycling performance with Air exposure and positive potential shock shows the capability of restoring the CO.sub.2 reduction activity by oxidizing surface adsorbed CO. The unchanged hydride content during the cycling performance with air exposure exhibits better stability performance than the reduced hydride content after cycling performance with positive potential shock, further demonstrating the hydride role of promoting CO.sub.2RR activity and stability. Isotopic analysis in D.sub.2O and K.sub.2CO.sub.3 reveals the participation pathway of hydride towards HCOO-, that hydride is able to form C—H bond in formate and is replenished from solution at negative potentials.
[0095] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
REFERENCES
[0096] (1) Whipple, D. T.; Kenis, P. J. A. Prospects of CO.sub.2 Utilization via Direct Heterogeneous Electrochemical Reduction. J. Phys. Chem. Lett. 2010. https://doi.org/10.1021/jz1012627.
[0097] (2) Costentin, C.; Robert, M.; Savéant, J. M. Catalysis of the Electrochemical Reduction of Carbon Dioxide. Chem. Soc. Rev. 2013. https://doi.org/10.1039/c2cs35360a.
[0098] (3) Quadrelli, E. A.; Centi, G.; Duplan, J. L.; Perathoner, S. Carbon Dioxide Recycling: Emerging Large-Scale Technologies with Industrial Potential. ChemSusChem. 2011. https://doi.org/10.1002/cssc.201100473.
[0099] (4) Appel, A. M.; Bercaw, J. E.; Bocarsly, A. B.; Dobbek, H.; Dubois, D. L.; Dupuis, M.; Ferry, J. G.; Fujita, E.; Hille, R.; Kenis, P. J. A.; Kerfeld, C. A.; Morris, R. H.; Peden, C. H. F.; Portis, A. R.; Ragsdale, S. W.; Rauchfuss, T. B.; Reek, J. N. H.; Seefeldt, L. C.; Thauer, R. K.; Waldrop, G. L. Frontiers, Opportunities, and Challenges in Biochemical and Chemical Catalysis of CO.sub.2 Fixation. Chemical Reviews. 2013. https://doi.org/10.1021/cr300463y.
[0100] (5) Aresta, M.; Dibenedetto, A.; Angelini, A. Catalysis for the Valorization of Exhaust Carbon: From CO.sub.2 to Chemicals, Materials, and Fuels. Technological Use of CO.sub.2. Chemical Reviews. 2014. https://doi.org/10.1021/cr4002758.
[0101] (6) Kuhl, K. P.; Hatsukade, T.; Cave, E. R.; Abram, D. N.; Kibsgaard, J.; Jaramillo, T. F. Electrocatalytic Conversion of Carbon Dioxide to Methane and Methanol on Transition Metal Surfaces. J. Am. Chem. Soc. 2014. https://doi.org/10.1021/ja505791r.
[0102] (7) Schouten, K. J. P.; Kwon, Y.; Van Der Ham, C. J. M.; Qin, Z.; Koper, M. T. M. A New Mechanism for the Selectivity to C1 and C2 Species in the Electrochemical Reduction of Carbon Dioxide on Copper Electrodes. Chem. Sci. 2011. https://doi.org/10.1039/c1sc00277e.
[0103] (8) Peterson, A. A.; Abild-Pedersen, F.; Studt, F.; Rossmeisl, J.; Nørskov, J. K. How Copper Catalyzes the Electroreduction of Carbon Dioxide into Hydrocarbon Fuels. Energy Environ. Sci. 2010. https://doi.org/10.1039/c0ee00071j.
[0104] (9) Kuhl, K. P.; Cave, E. R.; Abram, D. N.; Jaramillo, T. F. New Insights into the Electrochemical Reduction of Carbon Dioxide on Metallic Copper Surfaces. Energy Environ. Sci. 2012. https://doi.org/10.1039/c2ee21234j.
[0105] (10) Gattrell, M.; Gupta, N.; Co, A. A Review of the Aqueous Electrochemical Reduction of CO.sub.2 to Hydrocarbons at Copper. Journal of Electroanalytical Chemistry. 2006. https://doi.org/10.1016/j.jelechem.2006.05.013.
[0106] (11) Nie, X.; Esopi, M. R.; Janik, M. J.; Asthagiri, A. Selectivity of CO.sub.2 Reduction on Copper Electrodes: The Role of the Kinetics of Elementary Steps. Angew. Chemie—Int. Ed. 2013. https://doi.org/10.1002/anie.201208320.
[0107] (12) Hori, Y. Electrochemical CO.sub.2 Reduction on Metal Electrodes. In Modern Aspects of Electrochemistry; 2008. https://doi.org/10.1007/978-0-387-49489-0_3.
[0108] (13) Wang, X.; Varela, A. S.; Bergmann, A.; Kühl, S.; Strasser, P. Catalyst Particle Density Controls Hydrocarbon Product Selectivity in CO.sub.2 Electroreduction on CuOx. ChemSusChem 2017. https://doi.org/10.1002/cssc.201701179.
[0109] (14) Zhang, W.; Hu, Y.; Ma, L.; Zhu, G.; Wang, Y.; Xue, X.; Chen, R.; Yang, S.; Jin, Z. Progress and Perspective of Electrocatalytic CO.sub.2 Reduction for Renewable Carbonaceous Fuels and Chemicals. Advanced Science. 2018. https://doi.org/10.1002/advs.201700275.
[0110] (15) Kortlever, R.; Shen, J.; Schouten, K. J. P.; Calle-Vallejo, F.; Koper, M. T. M. Catalysts and Reaction Pathways for the Electrochemical Reduction of Carbon Dioxide. J. Phys. Chem. Lett. 2015. https://doi.org/10.1021/acs.jpclett.5b01559.
[0111] (16) Goyal, A.; Marcandalli, G.; Mints, V. A.; Koper, M. T. M. Competition between CO.sub.2 Reduction and Hydrogen Evolution on a Gold Electrode under Well-Defined Mass Transport Conditions. J. Am. Chem. Soc. 2020. https://doi.org/10.1021/jacs.9b10061.
[0112] (17) Higgins, D.; Hahn, C.; Xiang, C.; Jaramillo, T. F.; Weber, A. Z. Gas-Diffusion Electrodes for Carbon Dioxide Reduction: A New Paradigm. ACS Energy Lett. 2019. https://doi.org/10.1021/acsenergylett.8b02035.
[0113] (18) Asset, T.; Garcia, S. T.; Herrera, S.; Andersen, N.; Chen, Y.; Peterson, E. J.; Matanovic, I.; Artyushkova, K.; Lee, J.; Minteer, S. D.; Dai, S.; Pan, X.; Chavan, K.; Calabrese Barton, S.; Atanassov, P. Investigating the Nature of the Active Sites for the CO.sub.2 Reduction Reaction on Carbon-Based Electrocatalysts. ACS Catal. 2019. https://doi.org/10.1021/acscatal.9b01513.
[0114] (19) Guo, S.; Asset, T.; Atanassov, P. Catalytic Hybrid Electrocatalytic/Biocatalytic Cascades for Carbon Dioxide Reduction and Valorization. ACS Catal. 2021, 5172-5188. https://doi.org/10.1021/acscatal.0c04862.
[0115] (20) Bagger, A.; Ju, W.; Varela, A. S.; Strasser, P.; Rossmeisl, J. Electrochemical CO.sub.2 Reduction: A Classification Problem. ChemPhysChem 2017, 18 (22), 3266-3273. https://doi.org/10.1002/cphc.201700736.
[0116] (21) Azuma, M.; Hashimoto, K.; Hiramoto, M.; Watanabe, M.; Sakata, T. Electrochemical Reduction of Carbon Dioxide on Various Metal Electrodes in Low-Temperature Aqueous KHCO 3 Media. J. Electrochem. Soc. 1990. https://doi.org/10.1149/1.2086796.
[0117] (22) Hori, Y.; Wakebe, H.; Tsukamoto, T.; Koga, O. Electrocatalytic Process of CO Selectivity in Electrochemical Reduction of CO.sub.2 at Metal Electrodes in Aqueous Media. Electrochim. Acta 1994. https://doi.org/10.1016/0013-4686(94)85172-7.
[0118] (23) Rosen, J.; Hutchings, G. S.; Lu, Q.; Rivera, S.; Zhou, Y.; Vlachos, D. G.; Jiao, F. Mechanistic Insights into the Electrochemical Reduction of CO.sub.2 to CO on Nanostructured Ag Surfaces. ACS Catal. 2015. https://doi.org/10.1021/acscatal.5b00840.
[0119] (24) Back, S.; Yeom, M. S.; Jung, Y. Active Sites of Au and Ag Nanoparticle Catalysts for CO.sub.2 Electroreduction to CO. ACS Catal. 2015. https://doi.org/10.1021/acscatal.5b00462.
[0120] (25) Zhu, W.; Michalsky, R.; Metin, Ö.; Lv, H.; Guo, S.; Wright, C. J.; Sun, X.; Peterson, A. A.; Sun, S. Monodisperse Au Nanoparticles for Selective Electrocatalytic Reduction of CO.sub.2 to CO. J. Am. Chem. Soc. 2013. https://doi.org/10.1021/ja409445p.
[0121] (26) Luo, W.; Zhang, J.; Li, M.; Züttel, A. Boosting CO Production in Electrocatalytic CO.sub.2 Reduction on Highly Porous Zn Catalysts. ACS Catal. 2019. https://doi.org/10.1021/acscatal.8b05109.
[0122] (27) Varela, A. S.; Ju, W.; Bagger, A.; Franco, P.; Rossmeisl, J.; Strasser, P. Electrochemical Reduction of CO.sub.2 on Metal-Nitrogen-Doped Carbon Catalysts. ACS Catalysis. 2019. https://doi.org/10.1021/acscatal.9b01405.
[0123] (28) Delafontaine, L.; Asset, T.; Atanassov, P. Metal-Nitrogen-Carbon Electrocatalysts for CO.sub.2 Reduction towards Syngas Generation. ChemSusChem. 2020. https://doi.org/10.1002/cssc.201903281.
[0124] (29) Ju, W.; Bagger, A.; Hao, G. P.; Varela, A. S.; Sinev, I.; Bon, V.; Roldan Cuenya, B.; Kaskel, S.; Rossmeisl, J.; Strasser, P. Understanding Activity and Selectivity of Metal-Nitrogen-Doped Carbon Catalysts for Electrochemical Reduction of CO.sub.2. Nat. Commun. 2017. https://doi.org/10.1038/s41467-017-01035-z.
[0125] (30) Varela, A. S.; Ju, W.; Strasser, P. Molecular Nitrogen-Carbon Catalysts, Solid Metal Organic Framework Catalysts, and Solid Metal/Nitrogen-Doped Carbon (MNC) Catalysts for the Electrochemical CO.sub.2 Reduction. Advanced Energy Materials. 2018. https://doi.org/10.1002/aenm.201703614.
[0126] (31) Sen, S.; Liu, D.; Palmore, G. T. R. Electrochemical Reduction of CO.sub.2 at Copper Nanofoams. ACS Catal. 2014. https://doi.org/10.1021/cs500522g.
[0127] (32) Varela, A. S.; Ju, W.; Reier, T.; Strasser, P. Tuning the Catalytic Activity and Selectivity of Cu for CO.sub.2 Electroreduction in the Presence of Halides. ACS Catal. 2016. https://doi.org/10.1021/acscatal.5b02550.
[0128] (33) Hori, Y.; Takahashi, I.; Koga, O.; Hoshi, N. Selective Formation of C2 Compounds from Electrochemical Reduction of CO.sub.2 at a Series of Copper Single Crystal Electrodes. J. Phys. Chem. B 2002. https://doi.org/10.1021/jp013478d.
[0129] (34) Ahn, S. T.; Abu-Baker, I.; Palmore, G. T. R. Electroreduction of CO.sub.2 on Polycrystalline Copper: Effect of Temperature on Product Selectivity. Catal. Today 2017. https://doi.org/10.1016/j.cattod.2016.09.028.
[0130] (35) Tang, W.; Peterson, A. A.; Varela, A. S.; Jovanov, Z. P.; Bech, L.; Durand, W. J.; Dahl, S.; Nørskov, J. K.; Chorkendorff, I. The Importance of Surface Morphology in Controlling the Selectivity of Polycrystalline Copper for CO.sub.2 Electroreduction. Phys. Chem. Chem. Phys. 2012. https://doi.org/10.1039/c1cp22700a.
[0131] (36) Dutta, A.; Rahaman, M.; Luedi, N. C.; Mohos, M.; Broekmann, P. Morphology Matters: Tuning the Product Distribution of CO.sub.2 Electroreduction on Oxide-Derived Cu Foam Catalysts. ACS Catal. 2016. https://doi.org/10.1021/acscatal.6b00770.
[0132] (37) Hoang, T. T. H.; Ma, S.; Gold, J. I.; Kenis, P. J. A.; Gewirth, A. A. Nanoporous Copper Films by Additive-Controlled Electrodeposition: CO.sub.2 Reduction Catalysis. ACS Catal. 2017. https://doi.org/10.1021/acscatal.6b03613.
[0133] (38) Reske, R.; Mistry, H.; Behafarid, F.; Roldan Cuenya, B.; Strasser, P. Particle Size Effects in the Catalytic Electroreduction of CO.sub.2 on Cu Nanoparticles. J. Am. Chem. Soc. 2014. https://doi.org/10.1021/ja500328k.
[0134] (39) Wang, Y.; Shen, H.; Livi, K. J. T.; Raciti, D.; Zong, H.; Gregg, J.; Onadeko, M.; Wan, Y.; Watson, A.; Wang, C. Copper Nanocubes for CO.sub.2 Reduction in Gas Diffusion Electrodes. Nano Lett. 2019. https://doi.org/10.1021/acs.nanolett.9b02748.
[0135] (40) Lu, X.; Leung, D. Y. C.; Wang, H.; Leung, M. K. H.; Xuan, J. Electrochemical Reduction of Carbon Dioxide to Formic Acid. ChemElectroChem 2014. https://doi.org/10.1002/celc.201300206.
[0136] (41) Zhang, H.; Ma, Y.; Quan, F.; Huang, J.; Jia, F.; Zhang, L. Selective Electro-Reduction of CO.sub.2 to Formate on Nanostructured Bi from Reduction of BiOCl Nanosheets. Electrochem. commun. 2014. https://doi.org/10.1016/j.elecom.2014.06.013.
[0137] (42) Zhang, S.; Kang, P.; Meyer, T. J. Nanostructured Tin Catalysts for Selective Electrochemical Reduction of Carbon Dioxide to Formate. J. Am. Chem. Soc. 2014. https://doi.org/10.1021/ja4113885.
[0138] (43) Detweiler, Z. M.; White, J. L.; Bernasek, S. L.; Bocarsly, A. B. Anodized Indium Metal Electrodes for Enhanced Carbon Dioxide Reduction in Aqueous Electrolyte. Langmuir 2014. https://doi.org/10.1021/la501245p.
[0139] (44) Yang, Z.; Oropeza, F. E.; Zhang, K. H. L. P-Block Metal-Based (Sn, In, Bi, Pb) Electrocatalysts for Selective Reduction of CO.sub.2 to Formate. APL Mater. 2020. https://doi.org/10.1063/5.0004194.
[0140] (45) Pander, J. E.; Lum, J. W. J.; Yeo, B. S. The Importance of Morphology on the Activity of Lead Cathodes for the Reduction of Carbon Dioxide to Formate. J. Mater. Chem. A 2019. https://doi.org/10.1039/c8ta10752a.
[0141] (46) Jouny, M.; Luc, W.; Jiao, F. General Techno-Economic Analysis of CO.sub.2 Electrolysis Systems. Ind. Eng. Chem. Res. 2018. https://doi.org/10.1021/acs.iecr.7b03514.
[0142] (47) Vo, T.; Purohit, K.; Nguyen, C.; Biggs, B.; Mayoral, S.; Haan, J. L. Formate: An Energy Storage and Transport Bridge between Carbon Dioxide and a Formate Fuel Cell in a Single Device. ChemSusChem 2015. https://doi.org/10.1002/cssc.201500958.
[0143] (48) Yu, X.; Pickup, P. G. Recent Advances in Direct Formic Acid Fuel Cells (DFAFC). Journal of Power Sources. 2008. https://doi.org/10.1016/j.jpowsour.2008.03.075.
[0144] (49) El-Nagar, G. A.; Hassan, M. A.; Lauermann, I.; Roth, C. Efficient Direct Formic Acid Fuel Cells (DFAFCs) Anode Derived from Seafood Waste: Migration Mechanism. Sci. Rep. 2017. https://doi.org/10.1038/s41598-017-17978-8.
[0145] (50) Yan, B.; Concannon, N. M.; Milshtein, J. D.; Brushett, F. R.; Surendranath, Y. A Membrane-Free Neutral PH Formate Fuel Cell Enabled by a Selective Nickel Sulfide Oxygen Reduction Catalyst. Angew. Chemie—Int. Ed. 2017. https://doi.org/10.1002/anie.201702578.
[0146] (51) Qi, X.; Li, H. P.; Wu, X. F. A Convenient Palladium-Catalyzed Carbonylative Synthesis of Benzofuran-2(3 H)-Ones with Formic Acid as the CO Source. Chem.—An Asian J. 2016. https://doi.org/10.1002/asia.201600873.
[0147] (52) Long, B.; Long, Z. W.; Wang, Y. B.; Tan, X. F.; Han, Y. H.; Long, C. Y.; Qin, S. J.; Zhang, W. J. Formic Acid Catalyzed Gas-Phase Reaction of H.sub.2O with SO.sub.3 and the Reverse Reaction: A Theoretical Study. ChemPhysChem 2012. https://doi.org/10.1002/cphc.201100558.
[0148] (53) Koh, J. H.; Won, D. H.; Eom, T.; Kim, N. K.; Jung, K. D.; Kim, H.; Hwang, Y. J.; Min, B. K. Facile CO.sub.2 Electro-Reduction to Formate via Oxygen Bidentate Intermediate Stabilized by High-Index Planes of Bi Dendrite Catalyst. ACS Catal. 2017. https://doi.org/10.1021/acscatal.7b00707.
[0149] (54) Birdja, Y. Y.; Pérez-Gallent, E.; Figueiredo, M. C.; Göttle, A. J.; Calle-Vallejo, F.; Koper, M. T. M. Advances and Challenges in Understanding the Electrocatalytic Conversion of Carbon Dioxide to Fuels. Nature Energy. 2019. https://doi.org/10.1038/s41560-019-0450-y.
[0150] (55) Min, X.; Kanan, M. W. Pd-Catalyzed Electrohydrogenation of Carbon Dioxide to Formate: High Mass Activity at Low Overpotential and Identification of the Deactivation Pathway. J. Am. Chem. Soc. 2015. https://doi.org/10.1021/ja511890h.
[0151] (56) Zhao, S.; Li, S.; Guo, T.; Zhang, S.; Wang, J.; Wu, Y.; Chen, Y. Advances in Sn-Based Catalysts for Electrochemical CO.sub.2 Reduction. Nano-Micro Letters. 2019. https://doi.org/10.1007/s40820-019-0293-x.
[0152] (57) Feaster, J. T.; Shi, C.; Cave, E. R.; Hatsukade, T.; Abram, D. N.; Kuhl, K. P.; Hahn, C.; Nørskov, J. K.; Jaramillo, T. F. Understanding Selectivity for the Electrochemical Reduction of Carbon Dioxide to Formic Acid and Carbon Monoxide on Metal Electrodes. ACS Catal. 2017. https://doi.org/10.1021/acscatal.7b00687.
[0153] (58) Tang, Q.; Lee, Y.; Li, D. Y.; Choi, W.; Liu, C. W.; Lee, D.; Jiang, D. E. Lattice-Hydride Mechanism in Electrocatalytic CO.sub.2 Reduction by Structurally Precise Copper-Hydride Nanoclusters. J. Am. Chem. Soc. 2017. https://doi.org/10.1021/jacs.7b05591.
[0154] (59) Han, N.; Wang, Y.; Deng, J.; Zhou, J.; Wu, Y.; Yang, H.; Ding, P.; Li, Y. Self-Templated Synthesis of Hierarchical Mesoporous SnO2 Nanosheets for Selective CO.sub.2 Reduction. J. Mater. Chem. A 2019, 7 (3), 1267-1272. https://doi.org/10.1039/C8TA10959A.
[0155] (60) Kumar, B.; Atla, V.; Brian, J. P.; Kumari, S.; Nguyen, T. Q.; Sunkara, M.; Spurgeon, J. M. Reduced SnO2 Porous Nanowires with a High Density of Grain Boundaries as Catalysts for Efficient Electrochemical CO.sub.2-into-HCOOH Conversion. Angew. Chemie—Int. Ed. 2017. https://doi.org/10.1002/anie.201612194.
[0156] (61) Yang, F.; Elnabawy, A. O.; Schimmenti, R.; Song, P.; Wang, J.; Peng, Z.; Yao, S.; Deng, R.; Song, S.; Lin, Y.; Mavrikakis, M.; Xu, W. Bismuthene for Highly Efficient Carbon Dioxide Electroreduction Reaction. Nat. Commun. 2020. https://doi.org/10.1038/s41467-020-14914-9.
[0157] (62) Zhang, X.; Guo, S. X.; Gandionco, K. A.; Bond, A. M.; Zhang, J. Electrocatalytic Carbon Dioxide Reduction: From Fundamental Principles to Catalyst Design. Materials Today Advances. 2020. https://doi.org/10.1016/j.mtadv.2020.100074.
[0158] (63) Zhang, X.; Hou, X.; Zhang, Q.; Cai, Y.; Liu, Y.; Qiao, J. Polyethylene Glycol Induced Reconstructing Bi Nanoparticle Size for Stabilized CO.sub.2 Electroreduction to Formate. J. Catal. 2018. https://doi.org/10.1016/j.jcat.2018.06.019.
[0159] (64) Yang, H.; Han, N.; Deng, J.; Wu, J.; Wang, Y.; Hu, Y.; Ding, P.; Li, Y.; Li, Y.; Lu, J. Selective CO.sub.2 Reduction on 2D Mesoporous Bi Nanosheets. Adv. Energy Mater. 2018. https://doi.org/10.1002/aenm.201801536.
[0160] (65) Han, N.; Wang, Y.; Yang, H.; Deng, J.; Wu, J.; Li, Y.; Li, Y. Ultrathin Bismuth Nanosheets from in Situ Topotactic Transformation for Selective Electrocatalytic CO.sub.2 Reduction to Formate. Nat. Commun. 2018. https://doi.org/10.1038/s41467-018-03712-z.
[0161] (66) Lee, C. W.; Hong, J. S.; Yang, K. D.; Jin, K.; Lee, J. H.; Ahn, H. Y.; Seo, H.; Sung, N. E.; Nam, K. T. Selective Electrochemical Production of Formate from Carbon Dioxide with Bismuth-Based Catalysts in an Aqueous Electrolyte. ACS Catal. 2018. https://doi.org/10.1021/acscatal.7b03242.
[0162] (67) Ma, W.; Xie, S.; Zhang, X.-G.; Sun, F.; Kang, J.; Jiang, Z.; Zhang, Q.; Wu, D.-Y.; Wang, Y. Promoting Electrocatalytic CO.sub.2 Reduction to Formate via Sulfur-Boosting Water Activation on Indium Surfaces. Nat. Commun. 2019, 10 (1), 892. https://doi.org/10.1038/s41467-019-08805-x.
[0163] (68) Gao, S.; Lin, Y.; Jiao, X.; Sun, Y.; Luo, Q.; Zhang, W.; Li, D.; Yang, J.; Xie, Y. Partially Oxidized Atomic Cobalt Layers for Carbon Dioxide Electroreduction to Liquid Fuel. Nature 2016. https://doi.org/10.1038/nature16455.
[0164] (69) Li, F.; Xue, M.; Li, J.; Ma, X.; Chen, L.; Zhang, X.; MacFarlane, D. R.; Zhang, J. Unlocking the Electrocatalytic Activity of Antimony for CO.sub.2 Reduction by Two-Dimensional Engineering of the Bulk Material. Angew. Chemie—Int. Ed. 2017. https://doi.org/10.1002/anie.201710038.
[0165] (70) Chaplin, R. P. S.; Wragg, A. A. Effects of Process Conditions and Electrode Material on Reaction Pathways for Carbon Dioxide Electroreduction with Particular Reference to Formate Formation. Journal of Applied Electrochemistry. 2003. https://doi.org/10.1023/B:JACH.0000004018.57792.b8.
[0166] (71) He, S.; Ni, F.; Ji, Y.; Wang, L.; Wen, Y.; Bai, H.; Liu, G.; Zhang, Y.; Li, Y.; Zhang, B.; Peng, H. The P-Orbital Delocalization of Main-Group Metals to Boost CO.sub.2 Electroreduction. Angew. Chemie—Int. Ed. 2018. https://doi.org/10.1002/anie.201810538.
[0167] (72) Noda, H.; Ikeda, S.; Oda, Y.; Imai, K.; Maeda, M.; Ito, K. Electrochemical Reduction of Carbon Dioxide at Various Metal Electrodes in Aqueous Potassium Hydrogen Carbonate Solution. Bull. Chem. Soc. Jpn. 1990. https://doi.org/10.1246/bcsj.63.2459.
[0168] (73) Kortlever, R.; Peters, I.; Koper, S.; Koper, M. T. M. Electrochemical CO.sub.2 Reduction to Formic Acid at Low Overpotential and with High Faradaic Efficiency on Carbon-Supported Bimetallic Pd—Pt Nanoparticles. ACS Catal. 2015. https://doi.org/10.1021/acscatal.5b00602.
[0169] (74) Stalder, C. J.; Chao, S.; Wrighton, M. S. Electrochemical Reduction of Aqueous Bicarbonate to Formate with High Current Efficiency Near the Thermodynamic Potential at Chemically Derivatized Electrodes. J. Am. Chem. Soc. 1984. https://doi.org/10.1021/ja00324a046.
[0170] (75) Gao, D.; Zhou, H.; Cai, F.; Wang, D.; Hu, Y.; Jiang, B.; Cai, W. Bin; Chen, X.; Si, R.; Yang, F.; Miao, S.; Wang, J.; Wang, G.; Bao, X. Switchable CO.sub.2 Electroreduction via Engineering Active Phases of Pd Nanoparticles. Nano Res. 2017. https://doi.org/10.1007/s12274-017-15514-6.
[0171] (76) Rahaman, M.; Dutta, A.; Broekmann, P. Size-Dependent Activity of Palladium Nanoparticles: Efficient Conversion of CO.sub.2 into Formate at Low Overpotentials. ChemSusChem 2017. https://doi.org/10.1002/cssc.201601778.
[0172] (77) Jiang, T. W.; Zhou, Y. W.; Ma, X. Y.; Qin, X.; Li, H.; Ding, C.; Jiang, B.; Jiang, K.; Cai, W. Bin. Spectrometric Study of Electrochemical CO.sub.2Reduction on Pd and Pd—B Electrodes. ACS Catal. 2021. https://doi.org/10.1021/acscatal.0c03725.
[0173] (78) Abild-Pedersen, F.; Andersson, M. P. CO Adsorption Energies on Metals with Correction for High Coordination Adsorption Sites—A Density Functional Study. Surf. Sci. 2007. https://doi.org/10.1016/j.susc.2007.01.052.
[0174] (79) Chatterjee, S.; Griego, C.; Hart, J. L.; Li, Y.; Taheri, M. L.; Keith, J.; Snyder, J. D. Free Standing Nanoporous Palladium Alloys as CO Poisoning Tolerant Electrocatalysts for the Electrochemical Reduction of CO.sub.2 to Formate. ACS Catal. 2019. https://doi.org/10.1021/acscatal.9b00330.
[0175] (80) Klinkova, A.; De Luna, P.; Dinh, C. T.; Voznyy, O.; Larin, E. M.; Kumacheva, E.; Sargent, E. H. Rational Design of Efficient Palladium Catalysts for Electroreduction of Carbon Dioxide to Formate. ACS Catal. 2016. https://doi.org/10.1021/acscatal.6b01719.
[0176] (81) Zhou, F.; Li, H.; Fournier, M.; MacFarlane, D. R. Electrocatalytic CO.sub.2 Reduction to Formate at Low Overpotentials on Electrodeposited Pd Films: Stabilized Performance by Suppression of CO Formation. ChemSusChem 2017. https://doi.org/10.1002/cssc.201601870.
[0177] (82) Jiang, B.; Zhang, X. G.; Jiang, K.; Wu, D. Y.; Cai, W. Bin. Boosting Formate Production in Electrocatalytic CO.sub.2 Reduction over Wide Potential Window on Pd Surfaces. J. Am. Chem. Soc. 2018. https://doi.org/10.1021/jacs.7b12506.
[0178] (83) Takashima, T.; Suzuki, T.; Irie, H. Electrochemical Reduction of Carbon Dioxide to Formate on Palladium-Copper Alloy Nanoparticulate Electrode. Electrochemistry 2019. https://doi.org/10.5796/electrochemistry.18-00086.
[0179] (84) Bai, X.; Chen, W.; Zhao, C.; Li, S.; Song, Y.; Ge, R.; Wei, W.; Sun, Y. Exclusive Formation of Formic Acid from CO.sub.2 Electroreduction by a Tunable Pd—Sn Alloy. Angew. Chemie—Int. Ed. 2017. https://doi.org/10.1002/anie.201707098.
[0180] (85) Li, J.; Fan, R.; Hu, H.; Yao, C. Hydrogen Sensing Performance of Silica Microfiber Elaborated with Pd Nanoparticles. Mater. Lett. 2018, 212, 211-213. https://doi.org/https://doi.org/10.1016/j.matlet.2017.10.095.
[0181] (86) Dekura, S.; Kobayashi, H.; Kusada, K.; Kitagawa, H. Hydrogen in Palladium and Storage Properties of Related Nanomaterials: Size, Shape, Alloying, and Metal-Organic Framework Coating Effects. ChemPhysChem 2019, 20 (10), 1158-1176. https://doi.org/https://doi.org/10.1002/cphc.201900109.
[0182] (87) Manchester, F. D.; San-Martin, A.; Pitre, J. M. The H—Pd (Hydrogen-Palladium) System. J. Phase Equilibria 1994. https://doi.org/10.1007/BF02667685.
[0183] (88) Lee, J. H.; Kattel, S.; Jiang, Z.; Xie, Z.; Yao, S.; Tackett, B. M.; Xu, W.; Marinkovic, N. S.; Chen, J. G. Tuning the Activity and Selectivity of Electroreduction of CO.sub.2 to Synthesis Gas Using Bimetallic Catalysts. Nat. Commun. 2019. https://doi.org/10.1038/s41467-019-11352-0.
[0184] (89) Xu, W.; Fan, G.; Chen, J.; Li, J.; Zhang, L.; Zhu, S.; Su, X.; Cheng, F.; Chen, J. Nanoporous Palladium Hydride for Electrocatalytic N2 Reduction under Ambient Conditions. Angew. Chemie—Int. Ed. 2020. https://doi.org/10.1002/anie.201914335.
[0185] (90) Gao, D.; Zhou, H.; Cai, F.; Wang, J.; Wang, G.; Bao, X. Pd-Containing Nanostructures for Electrochemical CO.sub.2 Reduction Reaction. ACS Catalysis. 2018. https://doi.org/10.1021/acscatal.7b03612.
[0186] (91) Qiu, Y.; Xin, L.; Li, Y.; McCrum, I. T.; Guo, F.; Ma, T.; Ren, Y.; Liu, Q.; Zhou, L.; Gu, S.; Janik, M. J.; Li, W. BCC-Phased PdCu Alloy as a Highly Active Electrocatalyst for Hydrogen Oxidation in Alkaline Electrolytes. J. Am. Chem. Soc. 2018, 140 (48), 16580-16588. https://doi.org/10.1021/jacs.8b08356.
[0187] (92) Qiu, Y.; Xin, L.; Li, Y.; McCrum, I. T.; Guo, F.; Ma, T.; Ren, Y.; Liu, Q.; Zhou, L.; Gu, S.; Janik, M. J.; Li, W. BCC-Phased PdCu Alloy as a Highly Active Electrocatalyst for Hydrogen Oxidation in Alkaline Electrolytes. J. Am. Chem. Soc. 2018. https://doi.org/10.1021/jacs.8b08356.
[0188] (93) Yano, H.; Kataoka, M.; Yamashita, H.; Uchida, H.; Watanabe, M. Oxygen Reduction Activity of Carbon-Supported Pt—M (M=V, Ni, Cr, Co, and Fe) Alloys Prepared by Nanocapsule Method. Langmuir 2007. https://doi.org/10.1021/la070078u.
[0189] (94) Wang, S.; Tian, D.; Wang, X.; Qin, J.; Tang, Y.; Zhu, J.; Cong, Y.; Liu, H.; Lv, Y.; Qiu, C.; Gao, Z.; Song, Y. Uniform PdH0.33 Nanodendrites with a High Oxygen Reduction Activity Tuned by Lattice H. Electrochem. commun. 2019, 102, 67-71. https://doi.org/https://doi.org/10.1016/j.elecom.2019.04.002.
[0190] (95) Khanuja, M.; Mehta, B. R.; Agar, P.; Kulriya, P. K.; Avasthi, D. K. Hydrogen Induced Lattice Expansion and Crystallinity Degradation in Palladium Nanoparticles: Effect of Hydrogen Concentration, Pressure, and Temperature. J. Appl. Phys. 2009. https://doi.org/10.1063/1.3253733.
[0191] (96) Schirber, J. E.; Morosin, B. Lattice Constants of B-P d H x and B-P d D x with x near 1.0. Phys. Rev. B 1975, 12 (1), 117.
[0192] (97) Worsham, J. E.; Wilkinson, M. K.; Shull, C. G. Neutron-Diffraction Observations on the Palladium-Hydrogen and Palladium-Deuterium Systems. J. Phys. Chem. Solids 1957, 3 (3), 303-310. https://doi.org/https://doi.org/10.1016/0022-3697(57)90033-1.
[0193] (98) Eastman, J. A.; Thompson, L. J.; Kestel, B. J. Narrowing of the Palladium-Hydrogen Miscibility Gap in Nanocrystalline Palladium. Phys. Rev. B 1993. https://doi.org/10.1103/PhysRevB.48.84.
[0194] (99) Wolf, R. J.; Lee, M. W.; Ray, J. R. Pressure-Composition Isotherms for Nanocrystalline Palladium Hydride. Phys. Rev. Lett. 1994, 73 (4), 557-560. https://doi.org/10.1103/PhysRevLett.73.557.
[0195] (100) Lamber, R.; Wetjen, S.; Jaeger, N. I. Size Dependence of the Lattice Parameter of Small Palladium Particles. Phys. Rev. B 1995. https://doi.org/10.1103/PhysRevB.51.10968.
[0196] (101) Huang, Z.; Thomson, P.; Di, S. Lattice Contractions of a Nanoparticle Due to the Surface Tension: A Model of Elasticity. J. Phys. Chem. Solids 2007. https://doi.org/10.1016/j.jpcs.2007.01.016.
[0197] (102) Bragg, W. H.; Bragg, W. L. The Reflection of X-Rays by Crystals. Proc. R. Soc. London. Ser. A, Contain. Pap. a Math. Phys. Character 1913. https://doi.org/10.1098/rspa.1913.0040.
[0198] (103) Ohkawa, K.; Hashimoto, K.; Fujishima, A.; Noguchi, Y.; Nakayama, S. Electrochemical Reduction of Carbon Dioxide on Hydrogenstoring Materials: Part 1. The Effect of Hydrogen Absorption on the Electrochemical Behavior on Palladium Electrodes. J. Electroanal. Chem. 1993, 345 (1), 445-456. https://doi.org/https://doi.org/10.1016/0022-0728(93)80495-4.
[0199] (104) Stuve, E. M.; Madix, R. J.; Brundle, C. R. CO Oxidation on Pd(100): A Study of the Coadsorption of Oxygen and Carbon Monoxide. Surf. Sci. 1984. https://doi.org/10.1016/0039-6028(84)90235-8.
[0200] (105) Peter, M.; Adamovsky, S.; Flores Camacho, J. M.; Schauermann, S. Energetics of Elementary Reaction Steps Relevant for CO Oxidation: CO and O2 Adsorption on Model Pd Nanoparticles and Pd(111). Faraday Discussions. 2013. https://doi.org/10.1039/c3fd00001j.
[0201] (106) Peter, M.; Florescamacho, J. M.; Adamovski, S.; Ono, L. K.; Dostert, K. H.; O'Brien, C. P.; Roldancuenya, B.; Schauermann, S.; Freund, H. J. Trends in the Binding Strength of Surface Species on Nanoparticles: How Does the Adsorption Energy Scale with the Particle Size? Angew. Chemie—Int. Ed. 2013. https://doi.org/10.1002/anie.201209476.
[0202] (107) Guo, R.-H.; Hu, C.-C. The Relationships among Hydrogen Adsorption, CO Stripping, and Selectivity of CO 2 Reduction on Pd Nanoparticles. J. Electrochem. Soc. 2021. https://doi.org/10.1149/1945-7111/abf17e.
[0203] (108) García, G.; Koper, M. T. M. Stripping Voltammetry of Carbon Monoxide Oxidation on Stepped Platinum Single-Crystal Electrodes in Alkaline Solution. Phys. Chem. Chem. Phys. 2008. https://doi.org/10.1039/b803503m.
[0204] (109) Guo, R. H.; Liu, C. F.; Wei, T. C.; Hu, C. C. Electrochemical Behavior of CO.sub.2 Reduction on Palladium Nanoparticles: Dependence of Adsorbed CO on Electrode Potential. Electrochem. commun. 2017. https://doi.org/10.1016/j.elecom.2017.05.005.
[0205] (110) Guo, R.; Hu, C. The Relationships among Hydrogen Adsorption, CO Stripping, and Selectivity of CO 2 Reduction on Pd Nanoparticles. J. Electrochem. Soc. 2021. https://doi.org/10.1149/1945-7111/abf17e.
[0206] (111) Blom, M. J. W.; van Swaaij, W. P. M.; Mul, G.; Kersten, S. R. A. Mechanism and Micro Kinetic Model for Electroreduction of CO.sub.2 on Pd/C: The Role of Different Palladium Hydride Phases. ACS Catal. 2021, 6883-6891. https://doi.org/10.1021/acscatal.1c01325.
[0207] (112) Goods, S. H.; Guthrie, S. E. Mechanical Properties of Palladium and Palladium Hydride. Scr. Metall. Mater. 1992. https://doi.org/10.1016/0956-716X(92)90284-L.
[0208] (113) Al-Mufachi, N. A.; Rees, N. V.; Steinberger-Wilkens, R. Hydrogen Selective Membranes: A Review of Palladium-Based Dense Metal Membranes. Renewable and Sustainable Energy Reviews. 2015. https://doi.org/10.1016/j.rser.2015.03.026.
[0209] (114) Jewell, L. L.; Davis, B. H. Review of Absorption and Adsorption in the Hydrogen-Palladium System. Applied Catalysis A: General. 2006. https://doi.org/10.1016/j.apcata.2006.05.012.
[0210] (115) Gabrielli, C.; Grand, P. P.; Lasia, A.; Perrot, H. Investigation of Hydrogen Adsorption and Absorption in Palladium Thin Films. J. Electrochem. Soc. 2004. https://doi.org/10.1149/1.1797037.
[0211] (116) Wang, J.; Yu, L.; Hu, L.; Chen, G.; Xin, H.; Feng, X. Ambient Ammonia Synthesis via Palladium-Catalyzed Electrohydrogenation of Dinitrogen at Low Overpotential. Nat. Commun. 2018, 9 (1), 1795. https://doi.org/10.1038/s41467-018-04213-9.