DOUBLE PEROVSKITE MATERIAL AND PREPARATION METHOD THEREOF, AND REVERSIBLE PROTONIC CERAMIC ELECTROCHEMICAL CELL

Abstract

The present application relates to the field of a reversible protonic ceramic electrochemical cell, specifically, to a double perovskite material and preparation method thereof, and a reversible protonic ceramic electrochemical cell. The expression for the double perovskite material is PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6-, wherein is oxygen vacancy content. The present application also provides a preparation method for the double perovskite material and a reversible protonic ceramic electrochemical cell comprising the double perovskite material. The Cs.sup.+ doped double perovskite material provided by the present application has good stability, lower polarization impedance, and higher ORR/OER activity. The reversible protonic ceramic electrochemical cell provided by the present application has good stability, electrocatalytic activity, and electrochemical performance.

Claims

1. A double perovskite material, wherein the double perovskite material has an expression of PrBa.sub.1-xCs.sub.xCo.sub.2O.sub.6-; wherein is oxygen vacancy content.

2. The double perovskite material according to claim 1, wherein x is in a range from 0.01 to 0.15, preferably x is in a range from 0.05 to 0.125.

3. The double perovskite material according to claim 1, wherein the double perovskite material has a tetragonal layered perovskite structure; preferably, the lattice parameters are as follows: 3.90450.1 for a, 3.90450.1 for b, and 7.65720.1 for c.

4. The double perovskite material according to claim 1, wherein the expression is PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6-.

5. A preparation method for the double perovskite material according to claim 1, wherein the preparation method comprises the following steps: 1) dissolving praseodymium nitrate, barium nitrate, cesium nitrate, and cobalt nitrate in water to obtain a liquid; then mixing the liquid with ethylenediaminetetraacetic acid, citric acid, and ammonia water, adjusting pH to 7 to 8, and obtaining a solution; and 2) heating the solution until gelatinous, subjecting the resultant to a high temperature treatment at 200 C. to 250 C. to obtain a precursor, and calcining the precursor.

6. The preparation method for the double perovskite material according to claim 5, wherein in step 1), the molar ratio of metal elements, ethylenediaminetetraacetic acid, and citric acid is (0.5 to 1.5):(0.5 to 1.5):(1 to 2); wherein the amount for the metal elements is the sum of Pr, Ba, Cs, and Co.

7. The preparation method for the double perovskite material according to claim 5, wherein in step 2), the solution is heated at a temperature of 80 C. to 100 C.; and/or, the high-temperature treatment is performed for 2 to 6 hours; and/or, the precursor is calcined at a temperature of 950 C. to 1050 C. for 2 to 4 hours.

8. A reversible protonic ceramic electrochemical cell, wherein the reversible protonic ceramic electrochemical cell comprises an anode support layer, an electrolyte, and an air electrode connected in sequence; the air electrode is prepared from the double perovskite material according to claim 1.

9. The reversible protonic ceramic electrochemical cell according to claim 8, wherein the electrolyte material comprises BaZr.sub.0.1Ce.sub.0.7Y.sub.0.1Yb.sub.0.1O.sub.3-, wherein is oxygen vacancy content; and/or, the material of the anode support layer comprises NiO and BaZr.sub.0.1Ce.sub.0.7Y.sub.0.1Yb.sub.0.1O.sub.3-, wherein the mass ratio of NiO and BaZr.sub.0.1Ce.sub.0.7Y.sub.0.1Yb.sub.0.1O.sub.3- is (5.5 to 6.5):(3.5 to 4.5); and/or the reversible protonic ceramic electrochemical cell further comprises a transition layer, wherein the transition layer is disposed between the anode support layer and the electrolyte; preferably, the transition layer comprises NiO and BaZr.sub.0.1Ce.sub.0.7Y.sub.0.1Yb.sub.0.1O.sub.3-; wherein the mass ratio of NiO and BaZr.sub.0.1Ce.sub.0.7Y.sub.0.1Yb.sub.0.1O.sub.3- is (5.5 to 6.5):(3.5 to 4.5).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to provide a clearer explanation of the examples of the present application and the technical solutions in the prior art, a brief introduction will be given below to the accompanying drawings required in the examples or prior art descriptions. It is evident that the drawings in the following description are some examples of the present application. For a person skilled in the art, other drawings can be obtained based on these drawings without creative labor.

[0045] FIG. 1 shows a refined XRD spectrum of air electrode material PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC) involved in Example 1 of the present application after calcining at 1000 C. for 2 hours;

[0046] FIG. 2 shows an XRD spectrum of air electrode material PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC) involved in Example 1 of the present application and electrolyte BZCYYb powder after co-firing at 950 C. for 2 hours in a high-temperature muffle furnace;

[0047] FIG. 3 shows an XRD spectrum of air electrode material PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC) involved in Example 1 of the present application after 10 hours of treatment with 30% water at 600 C.;

[0048] FIG. 4 shows a high-temperature in-situ XRD spectrum of air electrode material PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC) involved in Example 1 of the present application after calcining at 1000 C. for 2 hours;

[0049] FIG. 5 shows the X-ray photoelectron spectra (XPS) of the air electrode materials PBCsC and PBC involved in Example 1 of the present application, wherein a is Pr 3d, and b is Co 2p;

[0050] FIG. 6 shows the O1s X-ray photoelectron spectra of the air electrode materials PBCsC (6a) and PBC (6b) involved in Example 1 of the present application;

[0051] FIG. 7 shows the relaxation characterization diagram of the air electrode materials PBCsC and PBC involved in Example 1 of the present application;

[0052] FIG. 8 shows the area specific impedance diagram (8a) and impedance stability diagram (8b) of the symmetric cell involved in Example 1 of the present application with PBCsC as the electrode and BZCYYb1711 as the electrolyte support body in humidified air (3% H.sub.2O);

[0053] FIG. 9 shows the electrochemical stability of the symmetric cell involved in Example 1 of the present application with PBCsC and PBC as the electrode and BZCYYb1711 as the electrolyte support body in humidified air (3% H.sub.2O);

[0054] FIG. 10 shows the infrared spectra of PBCsC and PBC oxide involved in Example 1 of the present application after being treated at 600 C. in air containing 30% water vapor for 50 hours;

[0055] FIG. 11 shows the peak power density diagram of a single cell (Ni-BZCYYb1711transition layer Ni-BZCYYb1711BZCYYb1711PBCsC) prepared with PBCsC as the air electrode and Ni BZCYYb1711 as the fuel electrode support involved in Example 2 of the present application at 650 C. to 500 C. in FC mode (with humidified hydrogen gas on the anode side, and ambient air on the oxygen electrode side);

[0056] FIG. 12 shows the current density diagram corresponding to 1.3 V of a single cell (Ni-BZCYYb1711transition layer Ni-BZCYYb1711BZCYYb1711PBCsC) prepared with PBCsC as the air electrode and Ni BZCYYb1711 as the fuel electrode support involved in Example 2 of the present application when tested at 650 C. to 500 C. in EC mode (with humidified hydrogen gas on the anode side, and humidified air on the oxygen electrode side);

[0057] FIG. 13 shows the operational stability diagram of a single cell (Ni-BZCYYb1711transition layer Ni-BZCYYb1711BZCYYb1711PBCsC) prepared with PBCsC as the air electrode and Ni-BZCYYb1711 as the anode support involved in Example 2 of the present application when tested at 650 C. in single cell fuel cell mode and in electrolytic cell mode;

[0058] FIG. 14 shows the cyclic stability diagram of a single cell (Ni-BZCYYb 1711transition layer Ni-BZCYYb1711BZCYYb1711PBCsC) prepared with PBCsC as the air electrode and Ni BZCYYb1711 as the fuel electrode support involved in Example 2 of the present application when tested at 600 C.;

[0059] FIG. 15 shows the variation diagram of Faradaic efficiency with applied current density of a single cell (Ni-BZCYYb 1711transition layer Ni-BZCYYb1711BZCYYb1711PBCsC) prepared with PBCsC as air electrode and Ni BZCYYb1711 as anode support layer involved in Example 2 of the present application; and

[0060] FIG. 16 shows the variation diagram of hydrogen production rate with applied current density of a single cell (Ni-BZCYYb1711 Transition Ni-BZCYYb1711BZCYYb1711PBCsC) prepared with PBCsC as air electrode and Ni BZCYYb 1711 as anode support layer involved in Example 2 of the present application.

SPECIFIC MODES FOR CARRYING OUT THE EMBODIMENTS

[0061] In order to make the purpose, technical solutions, and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application are described clearly and completely as follows. Obviously, the described examples are a part of the examples of the present application, rather than the entire examples. Based on the examples in the present application, all other examples obtained by a person skilled in the art without creative labor fall within the scope of protection of the present application.

[0062] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods. If specific techniques or conditions are not specified in the examples, they are all carried out using conventional methods or according to the techniques or conditions described in the literature in the art, or according to the product manual. The reagents and instruments used without indication of manufacturers, are conventional products that can be purchased through legitimate channels.

[0063] The present application is further explained in conjunction with examples as follows.

[0064] The examples of the present application relate to the preparation and characterization of an air electrode material doped with low Lewis acid strength cationic Cs.sup.+. The molecular formula of the air electrode material is PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC). The oxygen reduction/evolution reaction activity and stability of the anode supported reversible protonic ceramic electrochemical cell are improved by doping of Cs ions on A site of perovskite material PrBaCo.sub.2O.sub.6-. The catalytic activity and stability of PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC) air electrode are improved by doping of Cs.sup.+ at A site. At 650 C., the single cell composed of Ni-BZCYYb1711| transition layer Ni-BZCYYb1711|BZCYYb1711|PBCsC has a maximum output power of 1.66 W cm.sup.2 in FC mode, and the polarization resistance of the cell is only 0.045 cm.sup.2. After introducing air containing 3% water vapor on the air electrode side, a current density of 2.85 A cm.sup.2 was obtained under conditions of 650 C. and voltage of 1.3 V. In the present application, the polarization impedance of PrBaCo.sub.2O.sub.6- air electrode can be significantly reduced and the electrochemical performance of the full cell can be improved by doping of low Lewis acid strength cationic Cs.sup.+. In electrolysis mode, the current density can also be significantly increased and excellent stability is exhibited.

[0065] In addition, there is currently relatively little research on the cycling stability of the anode supported reversible protonic ceramic electrochemical cell at medium and low temperatures, and there are extremely few characterization methods for the stability of the reversible protonic ceramic electrochemical cell. In order to characterize the cycling stability of the reversible protonic ceramic electrochemical cell involved in the present application, an example of the present application also provides a testing method. The main steps are as follows: the air electrode material is brushed onto the electrolyte membrane of the anode supported protonic conductor single cell, hydrogen gas containing 3% water vapor is introduced to the anode side, and air containing 3% water vapor is introduced to the air electrode side. Cyclic stability testing is conducted on a single cell, that is, the anode supported reversible protonic ceramic electrochemical cell is alternately cycled between fuel cell mode and electrolysis cell mode by applying a current of 0.5 A cm.sup.2, so as to evaluate the electrochemical stability of the air electrode.

[0066] In the following examples, the composition of the baseline sample is PrBaCo.sub.2O.sub.6-, and the preparation process thereof is the same as that in the example.

Example 1

[0067] The present Example provides a method for preparing the air electrode material PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- of an anode supported reversible protonic ceramic electrochemical cell. The specific steps are as follows: [0068] 1) according to the stoichiometric ratio of PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC), praseodymium nitrate, barium nitrate, cesium nitrate and cobalt nitrate were sequentially added to a deionized water solution; subsequently, citric acid was added at 1.5 times of the molar amount of metal ions, and ethylenediamine tetraacetic acid was added at 1 time of the molar amount of metal ions; wherein, praseodymium nitrate, barium nitrate, cesium nitrate, cobalt nitrate, citric acid and ethylenediamine tetraacetic acid were purchased from Aladdin Chemical Reagent Network; [0069] 2) a complexing agent was added to the solution dissolved with metal ions, ammonia water was added, and the pH value was adjusted to 7 to 8, and then the mixture was heated and stirred under the condition of magnetic stirring until most water was evaporated to obtain a gelatinous substance; [0070] 3) the gelatinous substance was dried in an air drying oven and at 250 C. for 2 hours to obtain a fluffy porous precursor; and [0071] 4) the precursor was placed in a high-temperature muffle furnace and calcined at 1000 C. for 2 hours to obtain the required air electrode material powder, PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (denoted as PBCsC), wherein 0.10.3.

Example 2

[0072] The present Example provides a fabrication procedure of a reversible anode supported protonic ceramic electrochemical cell of Ni-BZCYYb1711|transition layer Ni-BZCYYb1711|BZCYYb1711|PBCsC prepared with PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC) provided in Example 1 as the air electrode. The specific steps are as follows: [0073] (1) preparation of electrolyte layer slurry: 3 g of BZCYYb1711 powder, 0.1 g of fish oil dispersant, 0.8 g of anhydrous ethanol, and 0.8 g of butyl acetate were uniformly mixed to obtain BZCYYb1711 electrolyte layer slurry; preparation of transition layer slurry: 1.2 g of BZCYYb1711 powder, 1.8 g of nano-size nickel oxide, 0.3 g of graphite, 0.1 g of fish oil dispersant, 0.75 g of anhydrous ethanol, and 0.75 g of butyl acetate were uniformly mixed to obtain Ni BZCYYb1711 transition layer slurry; preparation of anode support layer slurry: 10 g of BZCYYb1711, 15 g of nickel oxide, 1.5 g of graphite, 1 g of fish oil dispersant, 3 g of anhydrous ethanol, and 3 g of butyl acetate were uniformly mixed to obtain an anode slurry; and the above-mentioned slurries were separately ball milled for 30 to 40 hours; [0074] (2) the electrolyte slurry, transition layer slurry, and anode slurry after ball milling were sequentially cast onto a thin PET (polyethylene terephthalate) release film, then, the electrolyte layer-transition layer-anode support layer tape after co-casting was natural dried in air for 12 hours, and then, the resulting green tape was punched into 15 mm diameter samples, and the samples were debound in a muffle furnace at 600 C. for 2 hours of; finally, the samples were placed in a high-temperature muffle furnace and sintered at 1450 C. for 5 hours to obtain the required anode supported half-cell; wherein the prepared anode supported half-cell includes a BZCYYb1711 electrolyte layer (with a thickness of 7 to 9 m), a Ni BZCYYb1711 transition layer (with a thickness of 30 m), and a Ni BZCYYb1711 anode support layer (with a thickness of 600 to 700 m); [0075] (3) 1 g of the air electrode powder PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- prepared in Example 1 was weighed and uniformly mixed with 0.6 g of terpineol to obtain the required air electrode slurry; and [0076] (4) the prepared air electrode slurry was brushed onto the electrolyte membrane of the half-cell, then placed in a 70 C. oven, after the cathode slurry was dried, the assembled full cell was calcined at 950 C. in a high-temperature muffle furnace for 2 hours before electrochemical performance testing in FC and EC modes.

Characterization Results

1. XRD Characterization

[0077] FIG. 1 shows a refined XRD spectrum of PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC) after calcining at 1000 C. for 2 hours; it shows that the synthesized PBCsC exhibits a single double perovskite phase structure. Meanwhile, the XRD refinement results show that the synthesized PBCsC has a tetragonal layered perovskite structure, with lattice parameters of a=b=3.9045 and c=7.6572 (refinement parameter: GOF=2.13).

[0078] FIG. 2 shows the chemical compatibility between the synthesized air electrode material PBCsC and the electrolyte BZCYYb1711 powder. From the figure, it can be seen that there is no chemical reactions between PBCsC and BZCYYb1711 after calcined at 950 C. for 2 hours in a high-temperature muffle furnace, indicating that PBCsC material has good chemical compatibility with BZCYYb1711 powder.

[0079] FIG. 3 shows an XRD spectrum of PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC) after 10 hours of treatment with air containing 30% water vapor at 600 C. for 10 hours; wherein the main peak of the XRD spectrum of the treated PBCsC shifted significantly towards a lower angle, possibly due to the expansion of the lattice caused by water vapor entering the lattice.

[0080] FIG. 4 shows a high temperature in-situ XRD spectrum of PrBa.sub.0.9Cs.sub.0.1Co.sub.2O.sub.6- (PBCsC) powder. It can be seen from the spectrum that no impure phase is generated in PBCsC powder during the continuous heating test from 100 C. to 700 C. (holding time at each temperature is 1 hour), indicating that PBCsC oxide exhibits good phase structure stability and chemical stability at high temperatures. In the high-temperature in-situ XRD testing of PBCsC oxides, as the testing temperature increases, the main peak of PBCsC shifts towards a lower angle, which can be attributed to the lattice expansion caused by the increase in temperature.

2. X-Ray Photoelectron Spectroscopy (XPS) Characterization

[0081] According to the fitting data, after Cs partially replaces the Ba element at A-site in PBC, the high valence state proportions of Pr (FIG. 5(a)) and Co (FIG. 5(b)) were further increased in order to maintain their own electrical neutrality. As shown in FIG. 5(a), the content of Pr.sup.4+ in PBC is 37.9%, while the content of Pr.sup.4+ in PBCsC increases to 41.1%. The Co element also showed a similar trend of change, as shown in FIG. 5(b). In PBC, the contents of Co.sup.3+ and Co.sup.4+ were 36.7% and 35.0%, respectively, while in PBCsC, these contents increased to 41.8% and 43.5%, respectively. The XPS results indicate that the doping of Cs into PBC leads to an increase in the high valence cation content of Pr and Co.

[0082] The corresponding O is XPS fitting data of PBC and PBCsC are shown in FIG. 6 (a, and b). The O1s of PBC and PBCsC can be divided into four subordinate peaks. The dependent peaks with binding energies around 528.3, 530.0, 531.4, and 533.4 eV are related to lattice oxygen (O.sub.lat), high oxidation oxygen (O.sup./O.sub.2.sup.2), adsorbed oxygen (O.sub.ads), and oxygen (OH.sup.) in the hydroxyl environment, respectively, wherein, the ratio of O.sup./O.sub.2.sup.2 and O.sub.lat reflects the content of oxygen vacancies, while the ratios in PBC and PBCsC are 1.49 and 2.03, respectively. In addition, the proportion of O.sup./O.sub.2.sup.2 in oxides is often considered to play a crucial role in the ORR process.

3. Relaxation Characterization

[0083] FIG. 7 shows the surface exchange coefficient k*.sub.chem and bulk diffusion coefficient D*.sub.chem of PBCsC and PBC tested in temperatures ranging from 550 C. to 650 C., wherein, the surface exchange coefficient of PBCsC tested at 650 C. was calculated to be 7.9810.sup.4 cm s.sup.1, which is higher than that of PBC tested under the same conditions (2.3110.sup.4 cm s.sup.1). The increase in k*.sub.chem value indicates that the PBCsC air electrode has a fast oxygen surface exchange kinetics, thereby accelerating the ORR reaction process. The results of D*.sub.chem also show a similar trend. Under testing condition of 650 C., the D*.sub.chem values of PBC and PBCsC are 2.6410.sup.5 and 9.0110.sup.5 cm.sup.2 s.sup.1, respectively. The larger the D*.sub.chem value of PBCsC, the better the oxygen diffusion kinetics thereof. In summary, the enhancement of electrocatalytic activity of the PBCsC air electrode may be due to the doping of the A-site dopant (Cs), which generates more oxygen vacancies and improves surface exchange kinetics.

4. Research on Electrochemical Impedance and Stability

[0084] The electrocatalytic activity of the PBCsC air electrode was studied for the first time by measuring the area specific resistance of a symmetric cell supported by BZCYYb1711 in moist air (3% H.sub.2O) at 700 C. to 500 C. As shown in FIG. 8(a), the area specific resistance values of the PBCsC air electrode at 700 C., 650 C., 600 C., 550 C., and 500 C. reach 0.067, 0.184, 0.276, 0.575, and 1.588 cm.sup.2, respectively. FIG. 8(b) shows the electrocatalytic activity of the PBC air electrode. Under the same testing conditions, the area specific resistance values of the PBC air electrodes at 700 C., 650 C., 600 C., 550 C., and 500 C. reach 0.113, 0.258, 0.372, 0.977, and 2.443 cm.sup.2, respectively. Compared with the PBC air electrode, the PBCsC air electrode has higher electrocatalytic activity.

[0085] FIG. 9 shows the stability of PBCsC and PBC in moist air (3% H.sub.2O). When exposed to moist air, the area specific resistance value of the PBC air electrode significantly increases with the extension of testing time. On the contrary, under the same testing conditions, the area specific resistance value of the PBCsC air electrode shows better stability. Based on the above analysis, a symmetric cell with the PBCsC air electrode exhibits better stability and higher electrocatalytic activity.

5. Characterization of Fourier Transform Infrared Spectra (FTIR)

[0086] FIG. 10 shows the Fourier transform infrared spectra of PBCsC and PBC air electrodes after 50 hours of treatment in moist air containing 30% water vapor at 600 C. FTIR measurement can identify hydroxyl signal values in oxides, with characteristic peaks appearing in the range of 3400 to 3800 cm.sup.1. The test results show that the hydroxyl peak intensity of PBCsC treated with 30% water vapor is slightly higher than that of PBC oxide, indicating that PBCsC exhibits better hydration behavior.

6. Electrochemical Performance Test

[0087] The cell prepared in Example 2 was subjected to electrochemical power density testing in fuel cell mode (FC mode) and current density testing in electrolysis mode (EC mode). FIG. 11 shows that a full cell composed of PBCsC involved in the present application as the air electrode is tested in fuel cell mode with humidified hydrogen gas introduced on the anode side and air atmosphere on the air electrode side. The power densities tested within the range of 650 C. to 500 C. are 1.66 W cm.sup.2, 1.19 W cm.sup.2, 0.72 W cm.sup.2, and 0.41 W cm.sup.2, respectively.

[0088] FIG. 12 shows the I-V curve diagram of a single cell (Ni-BZCYYb1711BZCYYb1711PBCsC) prepared with PBCsC involved in the present application as the air electrode and Ni-BZCYYb1711 as the fuel electrode support, tested in EC mode (with humidified hydrogen gas introduced on the anode side and humidified air introduced on the oxygen electrode side) within the range of 650 C. to 500 C., wherein, the electrolytic cell of the PBCsC air electrode also shows better electrolysis performance, with current densities of 2.85 A cm.sup.2, 1.48 A cm.sup.2, 0.71 A cm.sup.2, and 0.31 A cm.sup.2 under 1.3 V voltage conditions at 650 C., 600 C., 550 C., and 500 C., respectively.

7. Single Cell Stability and Cycle Test

[0089] FIG. 13 shows the long-term stability of the PBCsC air electrode with a current density of 0.5 A cm.sup.2 at 650 C. and operating in FC mode for 170 hours. In addition, due to the presence of moist air in the R-PCEC air electrode chamber, the resistance of the air electrode to steam is crucial for the stability of the cell. The full cell with the PBCsC air electrode shows good stability in electrolysis mode using moist air (3% H.sub.2O) as an oxidant, and runs stably for 200 hours at 0.5 A cm.sup.2 and 650 C. Cycling tests with FC and EC dual-mode switching every 2 hours were performed under 0.5 A cm.sup.2 and at a temperature of 600 C. (FIG. 14). The cell with the PBCsC air electrode shows good stability during 80 hours of reversible operation.

8. Faradaic Efficiency and Hydrogen Production Rate Test

[0090] Faradaic efficiency is crucial for hydrogen production in the electrochemical process of R-PCEC, defined as the ratio of the actual H.sub.2 production rate (detected by gas chromatography equipment) to the theoretical H.sub.2 production rate (calculated by applied current). FIG. 15(a, and b) shows the Faradaic efficiency and hydrogen production rate under different current densities at 600 C. in moist air (steam concentration of 30%). When the cell is tested at different current densities of 0.5 A cm.sup.2, 0.75 A cm.sup.2, and 1.0 A cm.sup.2, the Faradaic efficiency decreases from 85.37% to 60.86% and 48.88%, as shown in FIG. 15(a). In addition, at current densities of 0.5 A cm.sup.2, 0.75 A cm.sup.2, and 1.0 A cm.sup.2, the corresponding H.sub.2 generation rates increase from 2.98 to 3.18 and 3.41, as shown in FIG. 15(b).

[0091] Finally, it should be noted that the above examples are only used to illustrate the technical solution of the present application, and not to limit the technical solution of the present application. Although the present application has been described in detail with reference to the aforementioned examples, a person skilled in the art should understand that they can still modify the technical solutions recited in the aforementioned examples or equivalently replace some of the technical features thereof, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various examples of the present application.