CN111282582A

CN111282582A - Preparation method of foam nickel-based catalyst for hydrogen production by water electrolysis

Info

Publication number: CN111282582A
Application number: CN202010194049.0A
Authority: CN
Inventors: 董文钧; 江涵
Original assignee: Suzhou Chujie New Material Technology Co Ltd
Current assignee: Suzhou Chujie New Material Technology Co Ltd
Priority date: 2020-03-19
Filing date: 2020-03-19
Publication date: 2020-06-16
Also published as: WO2021184563A1

Abstract

The invention discloses a preparation method of a foam nickel-based catalyst for hydrogen production by water electrolysis, which comprises the following steps: dissolving ammonium perrhenate, thioacetamide, ammonium fluoride and hexamethylene tetramine in deionized water to obtain a precursor solution, transferring the precursor solution into a hydrothermal kettle, adding foamed nickel, and growing Re on the foamed nickel in situ through solvothermal one-pot reaction_xNi_3‑xS₂And (3) after the reaction of the ultrathin nanosheets and the ultrathin nanosheets, naturally cooling the ultrathin nanosheets, and taking out the product，Washing and drying to obtain the foam nickel-based Re_xNi_3‑xS₂A catalyst for hydrogen production by electrolyzing water with ultrathin nanometer sheet composite material. Rhenium doped modified transition metal nickel grown in situ on nickel foamThe sulfide ultrathin nanosheet composite material is used as a water electrolysis hydrogen production catalyst, so that the cost of the catalyst is reduced compared with a noble metal-based catalyst, and the intrinsic catalytic activity of the water electrolysis hydrogen production catalyst is improved compared with a transition metal sulfide nanosheet catalyst which is single in component and is not doped and modified.

Description

Preparation method of foam nickel-based catalyst for hydrogen production by water electrolysis

Technical Field

The invention relates to a preparation method of a catalyst for hydrogen production by nickel foam-based water electrolysis, belonging to the field of energy and catalytic materials.

Technical Field

Hydrogen energy is considered to be one of the most promising new energy sources in the 21 st century. As a clean and efficient renewable energy source, hydrogen can be produced by thermal conversion or by water decomposition reaction catalyzed by electric energy and light energy. The electrocatalytic decomposition of water is an efficient and environment-friendly hydrogen production technology, and has a wide application prospect, so that the development of an efficient and cheap catalyst for producing hydrogen by electrolyzing water is very important. At present, noble metal platinum and the like are considered as the most efficient catalysts for hydrogen production by water electrolysis, but the disadvantages of high price, low storage capacity and poor stability limit the large-scale application of the noble metal catalysts. Therefore, the development of a catalyst for hydrogen production by electrolyzing water with low cost, stability and high efficiency is an important problem to be solved urgently in the economic development of hydrogen. The transition metal has relatively low price, and the sulfide thereof has good electrocatalytic activity and is concerned by extensive researchers.

At present, transition metal compounds as electrocatalytic hydrogen evolution catalysts generally need to be loaded on other conductive substrates by using adhesives for convenient application, but the combination mode of the catalysts and the substrates is not firm, and seriously hinders charge transmission, and the full exposure of active sites of the catalysts is limited, so that the activity and the catalytic efficiency of the catalysts are reduced, and the waste of materials and energy is caused.

Disclosure of Invention

The invention provides a preparation method of a high-efficiency foam nickel-based catalyst for hydrogen production by water electrolysis, aiming at the problems of the existing hydrogen production electrocatalyst. The preparation method has the advantages of simple process flow, easy operation, hopeful mass production and the like, and the prepared catalyst has an ultrathin nanosheet structure and is loaded on the foamed nickel in situ. The stable structure of the self-growing ultrathin nano-sheet of the foam nickel with the macroporous structure improves the electron transfer rate, fully exposes the active sites of the catalyst, is favorable for mass transfer and hydrogen separation, and rhenium doping not only ensures that Ni is doped₃S₂The nano-flake grows into an ultrathin nano-flake which has rich edges, greatly increases the electrochemical active area, enables the nano-flake to grow in an oriented manner and exposes a high-index crystal face with the highest electrocatalytic HER activity

10} and simultaneously constructs a Re-S bond and regulates and controls Ni₃S₂The electronic structure improves the intrinsic activity of the water-hydrogen evolution through electrocatalytic decomposition, and finally forms high-efficiency foam nickel-based Re_xNi_3-xS₂(x is more than 0 and less than 3) ultrathin nanosheet composite material water electrolysis hydrogen production catalyst。

The technical scheme of the invention is as follows: a preparation method of a foam nickel-based catalyst for hydrogen production by water electrolysis comprises the following steps: dissolving ammonium perrhenate, thioacetamide, ammonium fluoride and hexamethylene tetramine in deionized water to obtain a precursor solution, transferring the precursor solution into a hydrothermal kettle, adding foamed nickel, and carrying out a solvothermal one-pot reaction containing two stages, wherein the temperature of the first stage is 120 ℃, the heat preservation time is 4 hours, the temperature of the second stage is 220 ℃, and the heat preservation time is 24 hours; and after the reaction is finished, naturally cooling, taking out the product, washing and drying to obtain the foam nickel-based catalyst for hydrogen production by water electrolysis.

Further, when the precursor solution is prepared, the mass ratio of the ammonium perrhenate, thioacetamide, ammonium fluoride, hexamethylene tetramine and deionized water is 3.3:6:5:6: 10.

Further, the size of the added nickel foam is 0.5X 4 cm²And immersing the foamed nickel in the precursor solution.

The invention has the beneficial effects that:

1. according to the invention, the rhenium-doped modified transition metal nickel sulfide ultrathin nanosheet in-situ grown on the foamed nickel is used as a catalyst for hydrogen production by electrolyzing water, so that the cost of the catalyst is reduced compared with that of a noble metal oxide catalyst.

2. According to the invention, the rhenium-doped modified transition metal nickel sulfide ultrathin nanosheet which grows on the foamed nickel in situ is used as the catalyst for hydrogen production by electrolyzing water, so that the intrinsic activity of the catalyst is improved and the exposure number of active sites is increased compared with a transition metal sulfide nanosheet catalyst which is single in component and is not doped and modified.

3. In the invention, perrhenate is directly added as a rhenium source in solvothermal one-pot reaction, and Ni is added under the action of a certain proportion of the rhenium source₃S₂Oriented growth to expose the high-index crystal face with highest electrocatalytic HER activity

10 }; at the same time, Re-S bond is constructed by doping rhenium, and Ni is regulated and controlled₃S₂Electricity (D) fromThe substructure improves the intrinsic activity of water evolution hydrogen of electrocatalytic decomposition; doping of rhenium to Ni₃S₂The nano-particles grow into ultrathin nano-sheets, the ultrathin nano-sheets have rich edges, the surface area of the material is increased, a large number of electrocatalytic active sites are provided, and the catalytic performance is further improved; finally, Re with stable structure, uniform components and improved performance is obtained_xNi_3-xS₂The doping modification method of the ultrathin nanosheet is simple and effective.

4. The catalyst of the invention has the structure of rhenium doped modified Ni loaded by macroporous foam nickel₃S₂Re of constitution_xNi_3-xS₂Compared with a common powdery or blocky catalyst, the in-situ growth of the foamed nickel improves the electron transfer rate, the structure of the complex nanosheet is favorable for mass transfer and hydrogen separation, and the ultrathin nanosheet has a large specific surface area and a large number of active edges, so that the catalytic active area is increased.

In conclusion, the rhenium ions are effectively doped with the modified Ni by adjusting the time, the temperature and the drug dosage of the solvothermal one-pot reaction₃S₂And oriented to grow to expose high index crystal face

10 ultra-thin rhenium doped Ni₃S₂The nano-sheets are uniformly grown on the foamed nickel in situ to obtain the foamed nickel base Re with stable structure and uniform components_xNi_3-xS₂A catalyst for hydrogen production by electrolyzing water with ultrathin nanometer sheet composite material.

Drawings

FIG. 1 shows the nickel foam base Re prepared in example 1_xNi_3-xS₂Catalyst for hydrogen production by electrolyzing water with ultrathin nanosheet composite material and foam nickel-based Ni prepared in comparative example 1₃S₂Preparing an X-ray diffraction pattern of the hydrogen electrocatalyst from the nanosheet composite material;

in FIG. 2, (a) is a nickel foam base Re obtained in example 1_xNi_3-xS₂An integral scanning electron microscope image of the catalyst for hydrogen production by electrolyzing water with the ultrathin nanosheet composite material; (b) for the foam obtained in example 1Nickel foam base Re_xNi_3-xS₂Scanning pictures of the ultrathin nanosheet composite material hydrogen production catalyst by water electrolysis under a high magnification;

in FIG. 3, (a) is a nickel foam base Re obtained in example 1_xNi_3-xS₂A high-resolution transmission electron microscope image of the catalyst for hydrogen production by electrolyzing water with the ultrathin nanosheet composite material; (b) for the foamed nickel base Re obtained in example 1_xNi_3-xS₂A high-resolution transmission electron microscope image of the ultrathin nanosheet composite material hydrogen production catalyst by water electrolysis under a higher magnification;

FIG. 4 shows the nickel foam base Re prepared in example 1_xNi_3-xS₂An atomic force microscope representation diagram of the catalyst for hydrogen production by electrolyzing water with the ultrathin nanosheet composite material;

FIG. 5 shows the nickel foam base Re obtained in example 1_xNi_3-xS₂The electrochemical performance diagram of the catalyst for hydrogen production by electrolyzing water with the ultrathin nanosheet composite material is as follows: linear sweep voltammetry curve (a) and tafel slope curve (b).

Detailed Description

The present invention will be specifically described or further illustrated below with reference to examples, which are intended to better understand the technical spirit of the present invention, but the scope of the present invention is not limited to the following embodiments.

Example 1:

solvothermal one-pot reaction: 6.6 mg of ammonium perrhenate, 12 mg of thioacetamide, 10 mg of ammonium fluoride and 12 mg of hexamethylenetetramine were dissolved in 20 mL of deionized water, and the solution was charged into a 100m L autoclave, and 0.5X 4 cm of a clean solution was placed in the autoclave²Foaming nickel, then placing the high-temperature high-pressure reaction kettle into a constant-temperature oven at 120 ℃, preserving heat for 4 hours, then heating to 220 ℃, preserving heat for 24 hours, naturally cooling, taking out, washing and drying to obtain the foam nickel-based Re_xNi_3-xS₂Ultra-thin nanosheet composite, numbered Re_xNi_3-xS₂/NF。

Comparative example 1:

the difference from example 1 is that: solvent(s)The same operation as that of the example 1 is carried out without adding ammonium perrhenate in the hot one-pot reaction, and the foam nickel-based Ni is obtained₃S₂Composite material, number Ni₃S₂/NF。

Catalyst structural characterization

FIG. 1 shows Re as a catalyst prepared in example 1_xNi_3-xS₂Ni prepared by/NF and comparative example 1₃S₂X-ray diffraction analysis pattern of/NF. As can be seen from fig. 1: ni was observed in the catalysts prepared in example 1 and comparative example 1₃S₂The diffraction peaks at 21.7 °, 31.1 °, 37.8 °, 38.2 °, 49.7 ° and 55.2 ° with the characteristic peaks of metallic nickel respectively correspond to Ni₃S₂The (101), (110), (003), (113) and (122) planes of (JCPDS No.44-1418) are marked with solid circular symbols in the figure, and the diffraction peaks at 44.5 °, 51.8 ° and 76.4 ° correspond to the elemental Ni in the base nickel foam (JCPDS No.04-0850) marked with inverted triangle symbols in the figure. Comparative example 1 is more significantly Ni (OH) in composition than example 1₂The diffraction peaks at 19.3 DEG, 33.1 DEG, 38.5 DEG and 59.0 DEG respectively correspond to Ni (OH)₂The (001), (100), (101) and (110) crystal planes of (JCPDS No.14-0117), marked with open circles in the figure, illustrate that rhenium doping can inhibit the oxidation of nickel by hydrogen. In addition, no other miscellaneous peaks appear in the figure, showing higher purity.

FIG. 2 shows Re as a catalyst prepared in example 1_xNi_3-xS₂Scanning electron micrographs of/NF (a, b at different magnifications). The macroporous foam nickel skeleton can be observed in the graph 2a, and the nanosheets grow in situ onto the macroporous foam nickel skeleton. 2b it can be observed that the surface of the nickel foam skeleton is uniformly and vertically grown with Re_xNi_3-xS₂Nanosheets, Re_xNi_3-xS₂The nano sheets are tightly clustered, rich open gaps and edges are exposed, and the structure provides a wide space for mass transfer and hydrogen evolution.

FIG. 3 shows Re as a catalyst prepared in example 1_xNi_3-xS₂High resolution transmission electron micrographs of/NF (a, b at different magnifications). 3a is observedThe nano-sheet has uniform contrast and complete structure. 3b is Ni₃S₂The (110) and (003) planes of (A) are clearly visible, indicating that Ni is present₃S₂Exposed crystal face is high index crystal face with highest electrocatalytic HER activity

10}. No clear ReS was observed at the same time₂The lattice fringes of (a), indicate that nickel and rhenium do not form a complex of two sulfides or a polysulfide containing two metal elements.

FIG. 4 shows Re as a catalyst prepared in example 1_xNi_3-xS₂Atomic force microscopy characterization of/NF Each Re_xNi_3-xS₂The thickness of the nanosheet is about 1.5 nm, indicating that it is only 2-3 molecular layers thick, demonstrating that the rhenium is doped with Ni₃S₂Re formed by nanosheets_xNi_3-xS₂Is an ultrathin nanometer sheet.

FIG. 5 shows Re_xNi_3-xS₂The electrolytic water performance curve diagram of the/NF composite material is respectively a linear sweep voltammetry curve (a) and a tafel slope curve (b).

Testing of catalyst Performance

The catalyst Re prepared in example 1 was used_xNi_3-xS₂Catalyst Ni prepared by/NF and comparative example 1₃S₂and/NF is used for the performance test of the experiment for producing hydrogen by electrolyzing water. The test adopts a three-electrode system to test a linear sweep voltammetry curve, a Tafel slope curve, an electrochemical impedance spectrum Nyquist curve and an overpotential histogram, wherein the three-electrode system is divided into a working electrode, a reference electrode and a counter electrode. The reference electrode is an Ag/AgCl electrode, the counter electrode is a carbon rod, the working electrode is the catalyst material, and the platinum sheet electrode clamp is used for clamping the catalyst and then directly used as the working electrode.

The above experiments were all performed in 1.0M KOH solution, where the test conditions were: the linear scan rate is 1 mVs^-1The tafel slope curve is fitted by a linear sweep voltammetric curve.

FIG. 5 shows Re_xNi_3-xS₂The electrolytic water performance curve diagram of the/NF composite material is respectively a linear sweep voltammetry curve (a) and a tafel slope curve (b). As is apparent from fig. 5 (a): re_xNi_3-xS₂/NF at 10 mA cm^-2Overpotential as low as 62 mV compared with Ni₃S₂The NF material has lower overpotential and shows higher catalytic performance; as is apparent from fig. 5 (b): re_xNi_3-xS₂The Tafel slope of the/NF composite material is 113 mV decade^-1Compare Ni₃S₂the/NF material has a smaller Tafel slope. The reason is that the preparation method of the foam nickel in-situ growth is beneficial to improving the electron transfer rate in the electrocatalysis process so as to accelerate the speed of the electrocatalysis hydrogen evolution reaction; doping of rhenium to Ni₃S₂Oriented growth to expose the high-index crystal face with highest electrocatalytic HER activity

10, a Re-S bond is further constructed, and Ni is regulated and controlled simultaneously₃S₂The electronic structure improves the intrinsic activity of the water and hydrogen evolution through electrocatalysis decomposition; doping of rhenium to Ni₃S₂The nano-particles grow into ultrathin nano-sheets, the ultrathin nano-sheets have rich edges, the surface area of the material is increased, a large number of electrocatalytic active sites are provided, and the catalytic performance is further improved; the specific surface area of the three-dimensional macroporous foam nickel framework loaded ultrathin nanosheets is large and stable, and the three-dimensional macroporous foam nickel framework loaded ultrathin nanosheets are beneficial to full exposure of electrocatalytic active sites, mass transfer and hydrogen gas precipitation. The solvent thermal one-pot reaction is used for preparing foam nickel-based Re_xNi_3-xS₂The preparation method of the ultrathin nano-sheet composite material integrates the combined action of various modification means, and effectively improves the foam nickel-based Re_xNi_3-xS₂The intrinsic catalytic activity of the catalyst for hydrogen production by electrolyzing water and the hydrogen production efficiency by electrolyzing water are both provided by the ultrathin nanosheet composite material.

Comparative example 2:

solvothermal one-pot reaction: 6.6 mg ammonium perrhenate, 12 mg thioacetamide, 10 mg ammonium fluoride and 12 mg hexamethylenetetramine were dissolved in 20 mL to be deionizedAdding the obtained water into a high-temperature high-pressure reaction kettle of 100m L, and adding cleaned 0.5 × 4 cm²Foaming nickel, then placing the high-temperature high-pressure reaction kettle into a constant-temperature oven at 120 ℃, preserving heat for 2 hours, then heating to 220 ℃, preserving heat for 6 hours, naturally cooling, taking out, washing and drying to obtain the foamed nickel base 8h-Re_xNi_3-xS₂A composite material.

The catalyst performance was tested as in example 1, 8h-Re prepared in this comparative example 2_xNi_3-xS₂/NF at 10 mA cm^-2The overpotential is 150mV, the Tafel slope is 131 mV decade^-1The catalytic performance is inferior to that of Re prepared in example 1_xNi_3-xS₂and/NF. It is shown that the adoption of too short reaction time is not favorable for forming the Re-doped ultrathin nano-sheet composite material with high catalytic performance and good crystallinity.

Comparative example 3:

solvothermal one-pot reaction: 6.6 mg of ammonium perrhenate, 12 mg of thioacetamide, 10 mg of ammonium fluoride and 12 mg of hexamethylenetetramine were dissolved in 20 mL of deionized water, and the solution was charged into a 100m L autoclave, and 0.5X 4 cm of a clean solution was placed in the autoclave²Foaming nickel, then placing the high-temperature high-pressure reaction kettle into a constant-temperature oven at 120 ℃, preserving heat for 8 hours, then heating to 220 ℃, preserving heat for 48 hours, naturally cooling, taking out, washing and drying to obtain the foamed nickel base 56h-Re_xNi_3-xS₂An ultrathin nano-sheet composite material.

56h-Re prepared in comparative example 3 was subjected to the catalytic performance test in accordance with the procedure of example 1_xNi_3-xS₂/NF at 10 mA cm^-2The overpotential is 169 mV, the Tafel slope is 149mV decade^-1The catalytic performance is inferior to that of Re prepared in example 1_xNi_3-xS₂and/NF. The longer reaction time is adopted to reduce the catalytic performance of the composite material, which is probably because the Re-doped ultrathin nano-sheet structure is damaged at high temperature for a long time.

Claims

1. The preparation method of the foam nickel-based catalyst for hydrogen production by water electrolysis is characterized by comprising the following steps:

dissolving ammonium perrhenate, thioacetamide, ammonium fluoride and hexamethylene tetramine in deionized water to obtain a precursor solution, transferring the precursor solution into a hydrothermal kettle, adding foamed nickel, and carrying out a solvothermal one-pot reaction containing two stages, wherein the temperature of the first stage is 120 ℃, the heat preservation time is 4 hours, the temperature of the second stage is 220 ℃, and the heat preservation time is 24 hours; and after the reaction is finished, naturally cooling, taking out the product, washing and drying to obtain the foam nickel-based catalyst for hydrogen production by water electrolysis.

2. The preparation method according to claim 1, wherein the mass ratio of ammonium perrhenate, thioacetamide, ammonium fluoride, hexamethylenetetramine and deionized water used in preparing the precursor solution is 3.3:6:5:6: 10.

3. The method of claim 1, wherein the added nickel foam has a size of 0.5 x 4 cm²And immersing the foamed nickel in the precursor solution.