NICKEL-IRON CATALYTIC MATERIAL, PREPARATION METHOD THEREFOR, AND USE THEREOF IN HYDROGEN PRODUCTION THROUGH WATER ELECTROLYSIS AND PREPARATION OF LIQUID SOLAR FUEL (LSF)

Abstract

A nickel-iron catalytic material, a preparation method thereof, and a use thereof in the hydrogen production through water electrolysis and the preparation of a liquid solar fuel (LSF) are provided. The nickel-iron catalytic material is prepared by using a soluble iron salt as a raw material and growing on a modified nickel substrate under mild conditions, and the nickel-iron catalytic material can be used in the industrial alkaline water electrolysis under harsh conditions. The nickel-iron catalytic material includes a nickel metal substrate and a catalytically-active layer with iron and nickel. When used to promote a water splitting reaction, the nickel-iron catalytic material can reduce the energy consumption per m.sup.3 of hydrogen production through industrial alkaline water electrolysis from 4.4 kWh to 4.01 kWh, thereby increasing the conversion of solar energy to methanol by 9.7%.

Claims

1. A nickel-iron catalytic material, comprising a nickel metal substrate, and a catalytically-active layer, wherein the catalytically-active layer comprises iron with a valence of >+3 and non-zero valent nickel.

2. The nickel-iron catalytic material according to claim 1, wherein the catalytically-active layer is attached to a surface of the nickel metal substrate.

3. The nickel-iron catalytic material according to claim 1, wherein the nickel metal substrate is at least one selected from the group consisting of nickel sheet, nickel wire mesh, nickel foam, and nickel powder.

4. The nickel-iron catalytic material according to claim 1, wherein a molar ratio of iron nickel in the catalytically-active layer is Fe/Ni=(2-50):100.

5. The nickel-iron catalytic material according to claim 1, wherein a molar ratio of iron to nickel in the catalytically-active layer is Fe/Ni=(7-18):100.

6. The nickel-iron catalytic material according to claim 1, wherein the catalytically-active layer has a thickness of 300 nm to 500 nm.

7. A preparation method of a nickel-iron catalytic material, comprising at least the following steps: statically soaking a nickel metal substrate in a solution with iron ions, and washing and drying the nickel metal substrate to obtain the nickel-iron catalytic material, wherein the nickel metal substrate is treated for 0.25 h to 6 h in a hydrogen-containing atmosphere at 100° C. to 400° C.; in the solution with iron ions, the iron ions are Fe.sup.2+ and/or Fe.sup.3+; in the solution with iron ions, the iron ions have a concentration of 1 mM to 15 mM; the statically soaking is conducted at 20° C. to 70° C. for 0.5 h to 20 h.

8. (canceled)

9. The preparation method according to claim 7, wherein the hydrogen-containing atmosphere comprises an inert gas; and the inert gas is at least one selected from the group consisting of nitrogen, helium, neon, argon, and xenon.

10. (canceled)

11. The preparation method according to claim 7, wherein the nickel metal substrate is treated for 1 h to 3 h in the hydrogen-containing atmosphere at 200° C. to 300° C.

12. (canceled)

13. The preparation method according to claim 7, wherein in the solution with iron ions, the iron ions have a concentration of 3 mM to 12 mM.

14. The preparation method according to claim 7, wherein in the solution with iron ions, the iron ions have a concentration of 5 mM to 10 mM.

15. (canceled)

16. The preparation method according to claim 7, wherein the solution with iron ions is subjected to an inert gas sparging treatment before use.

17. (canceled)

18. The preparation method according to claim 7, wherein the statically soaking is conducted at 30° C. to 60° C. for 2 h to 10 h.

19. The preparation method according to claim 7, wherein the statically soaking is conducted at 40° C. to 50° C. for 3 h to 6 h.

20. A method of using the nickel-iron catalytic material of claim 1, comprising: using the nickel-iron catalytic material as a catalyst of a water splitting and oxygen evolution reaction in an alkaline solution.

21. A method for producing hydrogen and/or oxygen through water electrolysis, comprising: placing an anode and a cathode in an alkaline electrolyte, and conducting the water electrolysis to produce hydrogen and/or oxygen, wherein the anode comprises an anode catalyst, and the anode catalyst is at least one selected from the group consisting of the nickel-iron catalytic material according to claim 1; and the cathode comprises a cathode catalyst, and the cathode catalyst is at least one selected from the group consisting of nickel and an alloy formed of nickel with at least one selected from the group consisting of molybdenum, tungsten, iron, and platinum; the alkaline electrolyte comprises at least one alkali metal hydroxide; the at least one alkali metal hydroxide in the alkaline electrolyte has a concentration of 1 mol/L to 6 mol/L; the water electrolysis is conducted at 25° C. to 90° C.

22. (canceled)

23. The method according to claim 21, wherein the alkaline electrolyte comprises at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

24. (canceled)

25. The method according to claim 21, wherein the at least one alkali metal hydroxide in the alkaline electrolyte has a concentration of 5 mol/L to 6 mol/L.

26. (canceled)

27. The method according to claim 21, wherein the water electrolysis is conducted at 60° C. to 90° C.

28. A production method of a liquid solar fuel (LSF), comprising at least, the following steps: a) using a solar photovoltaic system to convert solar energy into electric energy; b) using the electric energy obtained in step a) for water electrolysis to prepare hydrogen; and c) allowing the hydrogen obtained in step b) to react with carbon dioxide to produce methanol wherein a method used for the water electrolysis in step b) is the method according to claim 21, wherein the solar photovoltaic system in step a) is at least one selected from the group consisting of a silicon-based photovoltaic system, a gallium arsenide photovoltaic system, a cadmium telluride photovoltaic system, and a copper indium gallium selenide photovoltaic system.

29. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] FIG. 1 shows performance test curves of sample D1.sup.# in Comparative Example 1 and sample 1.sup.# in Example 1 under three-electrode conditions.

[0062] FIG. 2 shows water splitting performance curves of sample D1.sup.# in Comparative Example 1 and sample 1.sup.# in Example 1 that separately are assembled with a Raney nickel cathode catalytic material to form a two-electrode electrolysis cell.

[0063] FIG. 3 shows the comparison of scanning electron microscopy (SEM) images of sample 1.sup.# in Example 1 and a nickel substrate.

[0064] FIG. 4 shows a stability working curve of a two-electrode electrolysis cell assembled by sample 1.sup.# in Example 1 with the Raney nickel cathode catalytic material.

[0065] FIG. 5 shows a performance test curve of sample 2.sup.# in Example 2 under three-electrode conditions.

[0066] FIG. 6 shows a performance test curve of sample 3.sup.# in Example 3 under three-electrode conditions.

[0067] FIG. 7 shows a performance test curve of sample 4.sup.# in Example 4 under three-electrode conditions.

[0068] FIG. 8 shows an X-ray photoelectron spectroscopy (XPS) Ni2p spectrum of nickel in the catalytically-active layer of sample 1.sup.# in Example 1.

[0069] FIG. 9 shows an XPS Fe2p spectrum of iron in the catalytically-active layer of sample 1.sup.# in Example 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] The present disclosure will be further described below through specific examples, and the examples are merely exemplary rather than restrictive. Unless otherwise specified, the raw materials in the examples are all commercially purchased and are directly used without special treatment; and the test devices adopt parameters recommended by the manufacturers.

[0071] In the process of the examples, the solar power generation device used has a power generation capacity of Q=10 MW, and is coupled with an alkaline water electrolysis device for hydrogen production and a carbon dioxide hydrogenation device. The carbon dioxide hydrogenation device adopts a ZnOZrO.sub.2 catalyst and conducts a reaction at 5 MPa, 330° C., and gas hourly space velocity (GHSV) of 24,000 mL h.sup.−1 g.sup.−1, with a carbon dioxide conversion rate of 11% and a methanol selectivity of 80%. According to calculation by the reaction equation

##STR00002##

and the ideal-gas equation, under standard conditions, each m.sup.3 of H.sub.2 can convert about 0.03 m.sup.3 of CO.sub.2 into methanol in a single cycle. In addition, under the conditions of 30% KOH and 80° C., a commercially-available alkaline water electrolysis device for hydrogen production (which is obtained by the assembly of 280 electrolysis cells and the diameter of the working area is 1.6 m) needs to consume P kWh per m.sup.3 of hydrogen production. A volume V of CO.sub.2 converted per hour by the solar power generation device with a coupled power generation capacity of Q=10 MW can be calculated by the following formula:

[00001]$V=\frac{Q\times 10^3}{P}\times 0.03m^3.$

[0072] In the examples, the commercially-available alkaline water electrolysis device for hydrogen production, the nickel mesh, and the Raney nickel are all purchased from Suzhou Jingli Hydrogen Production Equipment Co., Ltd.

[0073] In the examples, the three-electrode test is conducted at the INTERFACE 5000 electrochemical workstation of Garmy Instruments Inc.

[0074] In the examples, the morphology and surface element analysis of a sample is conducted by a Quanta 200 FEG scanning electron microscope with an energy spectrum.

[0075] In the examples, the XPS analysis of the sample is conducted by a VG ESCALAB MK2 X-ray energy spectrometer.

COMPARATIVE EXAMPLE 1

[0076] The nickel mesh and Raney nickel used in a commercially-available alkaline water electrolysis industrial device respectively served as a cathode and an anode to test the water electrolysis performance under strong alkali and high temperature (30% KOH, 80° C.), which was a basic reference comparative example.

[0077] (1) A 60-mesh Raney nickel cathode catalyst for commercially-available alkaline water electrolysis industrial devices was soaked in a 1 M NaOH solution for 24 h, then rinsed with deionized water until a resulting washing liquid was neutral, and dried at room temperature.

[0078] (2) A 60-mesh nickel mesh anode catalyst for commercially-available alkaline water electrolysis industrial devices was used directly and denoted as sample D1.sup.#.

[0079] (3) In a three-electrode system, Raney nickel was used as a counter electrode to test the water oxidation activity of the sample D1.sup.#, and results were shown in FIG. 1 (under strong alkali: 30% KOH, at room temperature). The initial overpotential for oxygen evolution was 270 mV, and an overpotential of 650 mV was required to reach a current density of 1000 mA.Math.cm.sup.−2.

[0080] (4) The sample D1.sup.# as an anode and Raney nickel as a cathode were assembled into an alkaline water electrolysis device for hydrogen production, and a working curve of an electrolysis cell (under strong alkali: 30% KOH, at high temperature: 80° C.) was determined. Results were shown in FIG. 2. A single electrolysis cell required a voltage of 1.985 V to achieve a current density of 250 mA.Math.cm.sup.−2.

[0081] (5) When a commercially-available alkaline water electrolysis device for hydrogen production used the Raney nickel and the nickel mesh as cathode/anode, the energy consumption per m.sup.3 of hydrogen production was about 4.4 kWh.

EXAMPLE 1

[0082] A new nickel-iron anode catalyst was prepared with a commercially-available nickel mesh as a substrate, and a commercially-available Raney nickel was used as a cathode to conduct water electrolysis under strong alkali and high temperature (30% KOH, 80° C.).

[0083] (1) A 60-mesh Raney nickel cathode catalyst for commercially-available alkaline water electrolysis industrial devices was soaked in a 1 M NaOH solution for 24 h, then rinsed with deionized water until a resulting washing liquid was neutral, and dried at room temperature.

[0084] (2) Preparation of a Nickel-Iron Mesh Anode Catalyst

[0085] (2-1) A 60-mesh nickel mesh for commercially-available alkaline water electrolysis industrial devices was placed in a tube furnace, incubated at 400° C. for 5 h in a stable atmosphere with a mixed gas of hydrogen and argon at a volume ratio of 1:10, and then cooled to room temperature to obtain a nickel mesh substrate with a specific surface species.

[0086] (2-2) Preparation of a reaction solution: Iron(III) chloride was dissolved in water to obtain a transparent solution of 10 mmol/L.

[0087] (2-3) Low-temperature chemical bath: The nickel mesh with the specific surface species obtained in step (2-1) was statically soaked in the stable reaction solution obtained in step (2-2) at 50° C. for 6 h.

[0088] (2-4) Rinsing of electrode sheet: The nickel mesh obtained in (2-3) was taken out, thoroughly washed with a large amount of water, and blow-dried or naturally air-dried to obtain the nickel-iron mesh catalyst, which was denoted as sample 1.sup.#. The morphological characterization was conducted through SEM on sample 1.sup.#, and the elemental composition of the nickel-iron oxide active layer was determined through energy dispersive X-ray spectroscopy (EDS). Results showed that, in sample 1.sup.#, the nickel-iron oxide active layer had a thickness of about 300 nm to 500 nm and an atomic ratio of about Fe/Ni=(10-15):100.

[0089] (3) In a three-electrode system, Raney nickel was used as a counter electrode to test the water oxidation activity of the sample 1.sup.# anode (under strong alkali: 30% KOH, at room temperature), and results were shown in FIG. 1. The initial overpotential for oxygen evolution of the sample 1.sup.# was 134 mV, and an overpotential of 380 mV was only required to reach a current density of 1,000 mA.Math.cm.sup.−2. Compared with sample D1.sup.# in Comparative Example 1, the initial overpotential for oxygen evolution was reduced by 136 mV, and the overpotential required at a current density of 1,000 mA.Math.cm.sup.−2 was reduced by 270 mV.

[0090] (4) The sample 1# as an anode and Raney nickel as a cathode were assembled into an alkaline water electrolysis device for hydrogen production, and a working curve of an electrolysis cell (under strong alkali: 30% KOH, at high temperature: 80° C.) was determined. Results were shown in FIG. 2. The comparison of SEM images of sample 1.sup.# and the nickel substrate in this example was shown in FIG. 3, and it indicates that, after the reaction was completed, the apparent morphology of the substrate did not change significantly. A single electrolysis cell required a voltage as low as 1.823 V to achieve a current density of 250 mA.Math.cm.sup.−2. The electrolysis device for hydrogen production assembled by sample 1.sup.# and Raney nickel still exhibited high working stability at a high current density of 500 mA.Math.cm.sup.−2, as shown in FIG. 4. Compared with sample D1.sup.# in Comparative Example 1, the new nickel-iron mesh catalyst of the present disclosure made the energy consumption per unit hydrogen production of the entire alkaline water electrolysis device reduced by about ΔP=0.39 kWh.

[0091] (5) According to the calculation based on the above data, with the process and the new nickel-iron mesh catalyst, each 10 MW photovoltaic device could convert about 75 m.sup.3 of CO.sub.2 into methanol per hour. Compared with Comparative Example 1, the conversion of carbon dioxide per hour could be increased by 9.7%. Results were shown in Table 1 below.

TABLE-US-00001 TABLE 1 CO.sub.2 conversion in the example and Comparative Example 1 (standard conditions) Energy consumption per m.sup.3 of Carbon dioxide hydrogen hydrogenation CO.sub.2 Anode Photovoltaic Water electrolysis production Catalyst ZnOZrO.sub.2 conversion catalyst power Anode Cathode Medium Temperature (KWh) Pressure Temperature per hour Sample 10 Nickel Raney 30% 80° C. 4.4 5 MPa 330° C. 68 m.sup.3 D1# MW h.sup.−1 mesh nickel KOH Sample 10 Nickel- Raney 30% 80° C. 4.01 5 MPa 330° C. 75 m.sup.3 1# MW h.sup.−1 iron nickel KOH mesh

EXAMPLE 2

[0092] The nickel metal substrate was not subjected to surface species modification, and iron was directly introduced to prepare a nickel-iron catalyst, as a comparative example.

[0093] (1) Preparation of a Nickel-Iron Mesh Anode Catalyst

[0094] (1-1) Preparation of a reaction solution: Iron(III) chloride was dissolved in water to obtain a transparent solution of 10 mmol/L.

[0095] (1-2) Low-temperature chemical bath: A 60-mesh nickel mesh for commercially-available alkaline water electrolysis industrial devices was statically soaked in the stable reaction solution obtained in step (1-1) at 50° C. for 6 h.

[0096] (1-3) Rinsing of electrode sheet: The nickel mesh obtained in (1-2) was taken out, thoroughly washed with a large amount of water, and blow-dried or naturally air-dried to obtain the nickel-iron mesh catalyst, which was denoted as sample 2.sup.#. The morphological characterization was conducted through SEM on sample 2.sup.#, and the elemental composition of the nickel-iron oxide active layer was determined through EDS. Results showed that, in sample 2.sup.#, the nickel-iron oxide active layer had a thickness of about 100 nm to 200 nm and an atomic ratio of about Fe/Ni=(8-12):100.

[0097] (2) In a three-electrode system, Raney nickel was used as a counter electrode to test the water oxidation activity of the sample 2.sup.# anode (under strong alkali: 30% KOH, at room temperature), and results were shown in FIG. 5. The initial overpotential for oxygen evolution of sample 2.sup.# was 310 mV, which was increased by 176 mV compared with that of sample 1.sup.#, and an overpotential of 380 mV could only achieve a current density of 25 mA.Math.cm.sup.−2.

[0098] It was confirmed that the nickel-iron anode catalyst growing on the metal nickel substrate without surface species modification could not exhibit prominent catalytic activity on water splitting and oxygen evolution.

EXAMPLE 3

[0099] Iron was introduced at an increased temperature to prepare a nickel-iron catalyst, as a comparative example.

[0100] (1) Preparation of a Nickel-Iron Mesh Anode Catalyst

[0101] (1-1) A 60-mesh nickel mesh for commercially-available alkaline water electrolysis industrial devices was placed in a tube furnace, incubated at 400° C. for 5 h in a stable atmosphere with a mixed gas of hydrogen and argon at a volume ratio of 1:10, and then cooled to room temperature to obtain a nickel mesh substrate with a specific surface species.

[0102] (1-2) Preparation of a reaction solution: Iron(III) chloride was dissolved in water to obtain a transparent solution of 10 mmol/L.

[0103] (1-3) Low-temperature chemical bath: A 60-mesh nickel mesh for commercially-available alkaline water electrolysis industrial devices was statically soaked in the stable reaction solution obtained in step (1-2) at 85° C. for 6 h.

[0104] (1-4) Rinsing of electrode sheet: The nickel mesh obtained in (1-3) was taken out, thoroughly washed with a large amount of water, and blow-dried or naturally air-dried to obtain the nickel-iron mesh catalyst, which was denoted as sample 3.sup.#. The morphological characterization was conducted through SEM on sample 3.sup.#, and the elemental composition of the nickel-iron oxide active layer was determined through energy dispersive X-ray spectroscopy (EDS). Results showed that, in sample 3.sup.#, the nickel-iron oxide active layer had a thickness of about 1000 nm to 1200 nm and an atomic ratio of about Fe/Ni=(15-18):100.

[0105] (2) In a three-electrode system, Raney nickel was used as a counter electrode to test the water oxidation activity of the sample 3.sup.# anode (under strong alkali: 30% KOH, at room temperature), and results were shown in FIG. 6. The initial overpotential for oxygen evolution of sample 3.sup.# was 270 mV, which was increased by 136 mV compared with that of sample 1.sup.#, and an overpotential of 380 mV could only achieve a current density of 210 mA.Math.cm.sup.−2. However, the performance was better than that of sample 2.sup.# in Example 2 where the metal nickel substrate was not subjected to surface species modification.

EXAMPLE 4

[0106] The reaction and sample preparation were conducted with a ferrous salt solution.

[0107] (1) Preparation of a Nickel-Iron Mesh Anode Catalyst

[0108] (1-1) A 60-mesh nickel mesh for commercially-available alkaline water electrolysis industrial devices was placed in a tube furnace, incubated at 400° C. for 5 h in a stable atmosphere with a mixed gas of hydrogen and argon at a volume ratio of 1:10, and then cooled to room temperature to obtain a nickel mesh substrate with a specific surface species.

[0109] (1-2) Preparation of a reaction solution: Iron(II) chloride was dissolved in water to obtain a transparent solution of 10 mmol/L.

[0110] (1-3) Low-temperature chemical bath: A 60-mesh nickel mesh for commercially-available alkaline water electrolysis industrial devices was statically soaked in the stable reaction solution obtained in step (1-2) at 50° C. for 6 h.

[0111] (1-4) Rinsing of electrode sheet: The nickel mesh obtained in (1-3) was taken out, thoroughly washed with a large amount of water, and blow-dried or naturally air-dried to obtain the nickel-iron mesh catalyst, which was denoted as sample 4.sup.#. The morphological characterization was conducted through SEM on sample 4.sup.#, and the elemental composition of the nickel-iron oxide active layer was determined through energy dispersive X-ray spectroscopy (EDS). Results showed that, in sample 4.sup.#, the nickel-iron oxide active layer had a thickness of about 200 nm to 300 nm and an atomic ratio of about Fe/Ni=(7-10):100.

[0112] (2) In a three-electrode system, Raney nickel was used as a counter electrode to test the water oxidation activity of the sample 4.sup.# anode (under strong alkali: 30% KOH, at room temperature), and results were shown in FIG. 7. The initial overpotential for oxygen evolution of the sample 4.sup.# was 230 mV, and an overpotential of 330 mV was only required to realize a current density of 300 mA.Math.cm.sup.−2. Compared with sample D1.sup.# in Comparative Example 1, the initial overpotential for oxygen evolution was reduced by 40 mV.

EXAMPLE 5

Characterization Results of Iron and Nickel in the Catalytically-Active Layer

[0113] FIG. 8 shows an XPS Ni2p spectrum of nickel in the catalytically-active layer of sample 1.sup.# in Example 1, and FIG. 9 shows an XPS Fe2p spectrum of iron in the catalytically-active layer of sample 1.sup.# in Example 1. The characterization results showed that the catalytically-active layer included iron with a valence of +2, +3, and >+3; and the catalytically-active layer included nickel with a valence of +2 and +3, which existed in the form of NiO, Ni(OH).sub.2, and NiOOH. Although the catalyst was on the metal nickel substrate, there was no zero-valent nickel signal according to the XPS data.

[0114] The above examples are merely a few examples of the present disclosure, and do not limit the present disclosure in any form. Although the present disclosure is disclosed as above with preferred examples, the present disclosure is not limited thereto. Some changes or modifications made by any technical personnel familiar with the profession using the technical content disclosed above without departing from the scope of the technical solutions of the present disclosure are equivalent to equivalent implementation cases and fall within the scope of the technical solutions.