A S anion-modified ReB2 catalyst, preparation method, and application thereof in electrocatalytic water splitting for hydrogen production over a wide pH range

Abstract

A kind of S anion modified ReB2 catalyst, preparation method and its application in wide pH value electrocatalytic water splitting hydrogen production, belong to the field of catalyst synthesis and electrocatalytic water splitting application technology. The present invention proposes a molten salt auxiliary preparation method of a S anion modified ReB2 catalyst, which is a step-by-step synthesis of S anion-doped diboride electrocatalyst (S-ReB2) under relatively mild conditions, and the nano-sheet morphology is conducive to exposing more catalytic active sites, while the doping of S regulates the electronic structure of the metal Re in the catalyst, so that S-ReB2 shows excellent catalytic performance in the electrolyte of different pH values ​​for electrocatalytic hydrogen evolution reaction (HER). The S anion modified ReB2 catalyst prepared by the present invention improves the problem that metal boride catalyst is easily corroded under strong acid / base strong oxidizing conditions, and improves the energy conversion efficiency of converting electrical energy into chemical energy.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst synthesis and electrocatalytic water splitting application, and specifically relates to a S anion-modified ReB2 catalyst, a preparation method and application thereof in electrocatalytic water splitting to produce hydrogen over a wide pH range. Background Art

[0002] Fossil fuel shortages and environmental pollution are receiving widespread attention worldwide and have become the focus of numerous researchers. To address this issue, developing clean and efficient secondary energy sources is considered a viable approach. Among numerous clean energy sources, hydrogen is considered one of the most promising due to its high energy density and zero carbon emissions. Compared to hydrogen produced from fossil fuels, water electrolysis produces hydrogen and oxygen, without carbon dioxide or other toxic or hazardous substances, making it a green hydrogen production technology. However, the water splitting reaction is thermodynamically and kinetically challenging, resulting in high energy consumption and cost. Therefore, the development of efficient water splitting catalysts is needed to enhance electrode activity, reduce electrolyzer energy consumption, and thus lower the cost of water electrolysis, thereby promoting its commercial application. Traditionally, Pt-based noble metals (such as Pt, Ru, Pd, and Ir) have been considered the most ideal catalysts due to their high efficiency and excellent stability. However, the high cost and low crustal reserves of noble metals have significantly limited their widespread application and become a major obstacle to competing with traditional energy sources. Therefore, finding alternative cheap materials has become a new research focus to achieve a better balance between performance, cost and stability.

[0003] Transition metal borides have adjustable composition and structure and their unique bonding characteristics give them excellent physical and chemical properties, which have attracted widespread attention from researchers. Boron (B) is a metalloid element with an electronegativity between metals and non-metals. Boron atoms have an electron-deficient structure, and the number of their valence electrons is less than the number of valence orbitals. This electron-deficient feature allows boron atoms to exhibit a rich covalent bonding pattern in different boride lattices. The rich composition, structure and bonding characteristics give borides significant bulk properties such as superconductivity, superhardness, and thermoelectricity, as well as surface catalytic properties for different chemical reactions. For example, Edward H. Sargent et al. reported a phase composition modulation method for preparing effective boride / borate-based catalysts. First, NiFe boride was synthesized and used as a template precursor to form an active NiFe borate catalyst. The boride-derived oxide was subjected to a 1M KOH electrolyte and a current density of 10 mA cm -2 The overpotential is 167mV, and the oxygen evolution is catalytic at 1000mAcm -2Zou Xiaoxin and others studied the high-temperature and high-pressure synthesis, structural analysis, and water splitting hydrogen properties of multiple α-MoB2, β-MoB2, MoB, and Mo2B. Among them, α-MoB2 containing a boron olefin subunit structure showed the best catalytic performance under acidic conditions, and could achieve the desired 1000 mA cm at a small overpotential (334 mV). -2 These catalysts have good catalytic performance in either acidic or alkaline environments, but have limited application in a wide pH range, which severely restricts their practical application in complex aqueous environments with different pH values. Therefore, designing electrocatalysts with good catalytic activity in a wide pH range is very important and remains a difficult challenge.

[0004] Anion doping has become an effective approach to improving the electrochemical performance of transition metal borides (TMBs). Heteroatom doping can effectively modulate the conductivity of catalysts, causing a shift in the catalyst's Fermi level. By replacing atoms in the lattice with impurity atoms, excess electrons or holes can be introduced into the material. The electronic interaction between heteroatoms and metal borides alters the inherent electron transfer process, thereby changing the local charge distribution at the active sites. Summary of the Invention

[0005] With the purpose of improving the energy conversion utilization rate and promoting the development of the hydrogen economy, the present invention proposes a S anion-modified ReB2 catalyst, a preparation method and its application in electrocatalytic water splitting to produce hydrogen under a wide pH value (wide pH refers to the ability to catalyze the electrocatalytic hydrogen evolution reaction under acidic, neutral and alkaline conditions).

[0006] The present invention proposes a molten salt-assisted preparation method for a S anion-modified ReB2 catalyst. This method involves synthesizing a S anion-doped diboride electrocatalyst (S-ReB2) in a single step under relatively mild conditions. The nanosheet morphology facilitates the exposure of more catalytically active sites. Simultaneously, the S doping modulates the electronic structure of the metal Re in the catalyst, enabling S-ReB2 to exhibit excellent catalytic performance for the electrocatalytic hydrogen evolution reaction (HER) in electrolytes with varying pH values. Specifically, overpotentials of 144 mV, 158 mV, and 139 mV (1.0 M KOH) are required in 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH, respectively, corresponding to a 10 mA cm -2 The current density is 200 nm and the electrocatalytic performance is 100 nm. The electrocatalytic performance is 100 nm. The electrocatalytic performance is 100 nm. The electrocatalytic performance is 100 nm. The electrocatalytic performance is 100 nm. The electrocatalytic performance is 100 nm. The electrocatalytic performance is 100 nm.

[0007] The present invention discloses a method for preparing a S anion-modified ReB2 catalyst, which comprises the following steps: first, uniformly mixing a rhenium source, a boron source, and a sulfur source, and grinding the mixture thoroughly to obtain a mixture A; then, uniformly mixing sodium chloride and potassium chloride with the mixture A, and grinding the mixture thoroughly again to obtain a mixture B; transferring the mixture B into a tubular furnace and calcining it at a high temperature in an Ar gas environment; cooling the mixture to room temperature after calcination, placing the obtained product into deionized water, stirring and washing it thoroughly, removing the supernatant, washing the obtained precipitate with ethanol, collecting the precipitate by centrifugation, and drying the mixture to obtain the S anion-modified ReB2 catalyst.

[0008] In the above method, the molar ratio of the rhenium source, the boron source and the sulfur source is 1:1-5:0.4-2;

[0009] The molar ratio of sodium chloride to potassium chloride is 1:1-2; the molar ratio of rhenium source to sodium chloride is 1:30-40;

[0010] In the above method, the high temperature calcination temperature is 650-1000°C, the high temperature calcination time is 0.5h-3h, and the heating rate during high temperature calcination is 3-6°C min -1 ;

[0011] In the above method, the product obtained by cooling to room temperature after calcination is placed in deionized water at 70 to 90°C and stirred and washed for 15 to 30 minutes;

[0012] In the above method, the sulfur source includes but is not limited to one or a mixture of organic sulfur-containing compounds such as sulfur powder, thiourea, thioacetamide, and mercaptans;

[0013] In the above method, the rhenium source includes but is not limited to one or a mixture of rhenium powder, rhenium dioxide, and ammonium rhenate;

[0014] In the above method, the boron source includes but is not limited to amorphous boron powder, sodium borohydride, boron trichloride or a mixture of the two or more thereof.

[0015] The S anion-modified ReB2 catalyst described in the present invention is prepared by the above method.

[0016] The S anion-modified ReB2 catalyst of the present invention can be used in the electrocatalytic water splitting and hydrogen production under a wide pH value.

[0017] Compared with the prior art, the present invention has the following innovations:

[0018] 1. The synthetic raw materials are cheap, the synthesis temperature is low, the synthesis method is novel, the controllability is high, and the sample properties are reproducible.

[0019] 2. The obtained S anion-modified ReB2 catalyst is an ultra-thin nanosheet structure (length 600-700 nm, thickness about 5 nm). This ultra-thin nanosheet greatly improves the electrochemical specific surface area and mass transfer efficiency of the obtained material.

[0020] 3. The obtained material is a new type of electrocatalytic water splitting catalyst. Sulfur doping regulates the surface electronic structure of the catalyst, so that S-ReB2 exhibits enhanced electrochemical performance for HER in three electrolytes with different pH values: 1.0M PBS, 0.5M H2SO4 and 1.0M KOH.

[0021] 4. The obtained S anion-modified ReB2 catalyst improves the problem that metal borides are easily corroded under strong acid / base oxidizing conditions, thereby improving the energy conversion efficiency of converting electrical energy into chemical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : XRD spectrum of the S-ReB2 catalyst (S-ReB2) prepared in Example 1;

[0023] Figure 2 : SEM image of the S-ReB2 catalyst (S-ReB2) prepared in Example 1;

[0024] Figure 3 : AFM image of the S-modified ReB2 catalyst (S-ReB2) prepared in Example 1;

[0025] Figure 4 : TEM and mapping images of the S-ReB2 catalyst (S-ReB2) prepared in Example 1; Figure 4 a is a TEM image of a single S-ReB2 nanosheet. Figure 4 b is the HRTEM image of S-ReB2, Figure 4 c~4f are STEM images of S-ReB2 and the presence and distribution of Re, B, and S in the nanosheets;

[0026] Figure 5 : Re 4f ( Figure 5 a) and B1s( Figure 5 b) XPS spectrum;

[0027] Figure 6 : The S-ReB2 catalyst prepared in Example 1 and ReB2, Re, Pt / C in 0.5M H2SO4 ( Figure 6 a), 1.0M PBS ( Figure 6 b), and 1.0 M KOH ( Figure 6 c) Hydrogen evolution reaction polarization curve;

[0028] Figure 7 : The S anion modified ReB2 catalyst (S-ReB2) prepared in Example 1 was heated in 0.5M H2SO4 ( Figure 7 a), 1.0M PBS ( Figure 7 b), and 1.0 M KOH ( Figure 7 Catalytic stability curve in c). DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and examples, but the protection scope of the present invention is not limited to the following examples.

[0030] Example 1

[0031] (1) Weigh 0.001 mol of rhenium powder (Re) and 0.002 mol of amorphous boron powder (B), and then weigh 0.001 mol of sulfur powder (S), grind and mix thoroughly to obtain a mixture A; n 铼 :n 硼 :n 硫 =1:2:1;

[0032] (2) Mixture A was uniformly mixed with 2.014 g of sodium chloride (0.035 mol) and 2.570 g of potassium chloride (0.035 mol), and the mixture was thoroughly ground for 10 min to obtain mixture B;

[0033] (3) Mixture B was transferred into a tube furnace and heated to 1000°C in an Ar gas environment, maintained for 1 h, and the heating rate was 5°C min -1 After the reaction, the temperature was cooled to room temperature, the sample was taken out and placed in 1000 mL of deionized water at 80°C, stirred and washed for 20 minutes, the supernatant was removed, and the resulting precipitate was washed with ethanol. The precipitate was collected by centrifugation and dried to obtain a S anion-modified ReB2 catalyst (product mass 0.18 g) with a metal rhenium to boron atom molar ratio of 1:2 (MB2), namely a metal boride water splitting catalyst.

[0034] The electrocatalytic water splitting HER properties of the material prepared by the above method were tested in a standard three-electrode electrolytic cell: 3.5 mg of the catalyst powder prepared in step (3) of this example was fully ground and dispersed in 100 μL of a mixed solution of perfluorosulfonic acid resin and isopropanol (the volume ratio was 1:10). Then 5 μL of the mixed solution was dropped on the surface of the glassy carbon electrode. After drying, the catalyst loading was 2.5 mg cm -2The working electrode was a 1.0M PBS (neutral), 0.5M H2SO4 (pH 0.3), or 1.0M KOH (pH 13.8) electrolyte. Under alkaline conditions (i.e., the electrolyte was 1.0M KOH), the reference electrode was a mercury oxide electrode, and the counter electrode was a graphite carbon rod. Under acidic and neutral conditions (i.e., the electrolyte was 1.0M PBS and 0.5M H2SO4), the counter electrode was a platinum wire, and the reference electrode was saturated silver chloride. It should be noted that all potentials obtained using mercury oxide and saturated silver chloride as reference electrodes in the electrocatalytic tests were converted to reversible hydrogen electrode potentials in the property maps. The external power supply was the main battery of the electrochemical workstation.

[0035] Some structural and performance studies were conducted on the materials prepared by the above method.

[0036] Figure 1 This is the XRD spectrum of the obtained material, which is well consistent with the hexagonal phase ReB2 (JCPDS No.73-1392). The results show that the metal diboride catalyst material was successfully prepared. Since the sulfur doping amount is very small, no characteristic diffraction peak related to sulfur is shown. Figure 2 This is a scanning electron micrograph (SEM) of the obtained material. The nanosheet structure of S-ReB2 stacked together after doping was observed by scanning electron microscopy. Figure 3 The AFM scan of the obtained material is obtained by atomic force microscopy (the inset is the corresponding height distribution curve). The thickness of the S-ReB2 nanosheet is about 5nm; Figure 4 a is a transmission electron microscopy (TEM) image of the obtained material. The results show that the sheet structure array is composed of irregular hexagonal nanosheets with a size of 600-700nm, which is consistent with the SEM results. In more detail, high-resolution transmission electron microscopy (HRTEM) tests of S-ReB2 were carried out. Figure 4 In b, two sets of lattice fringes show interplanar spacings of 0.251 and 0.186 nm, which match well with the (100) and (004) planes of the hexagonal phase of S-ReB2, respectively. The composition of S-ReB2 was also analyzed by scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDS) to confirm the presence and distribution of different elements in individual nanosheets. Figure 4 The results from c~4f show that Re, B, and S elements are evenly distributed throughout the nanosheet, further proving the successful incorporation of S and illustrating the successful preparation of sheet-structured S-ReB2 catalytic materials.

[0037] Figure 5 The Re 4f( Figure 5 b) and B1s XPS ( Figure 5b) Spectrum, it can be seen that the doping effect of S promotes electron transfer at the oxidized metal interface, exposing more catalytic active sites with high catalytic activity. Catalytic activity test:

[0038] Figure 6 In 0.5M H2SO4 ( Figure 6 a), 1.0M PBS ( Figure 6 b), and 1.0 M KOH ( Figure 6 c) The hydrogen evolution polarization curves measured by the three-electrode system of the electrochemical workstation under the conditions of overpotentials of 158 mV, 144 mV, and 139 mV, and the current density reached 10 mA cm -2 , which is better than the catalytic performance of ReB2 and Re, and close to that of commercial Pt / C, indicating that the catalyst prepared by the present invention has a good hydrogen evolution effect.

[0039] Figure 7 In 0.5M H2SO4 ( Figure 7 a), 1.0M PBS ( Figure 7 b) and 1.0 M KOH ( Figure 7 c) under the conditions of stability curve measured by the three-electrode system of electrochemical workstation, the catalytic performance was maintained for more than 25 hours with almost no attenuation, indicating that the catalyst prepared by the present invention has good stability.

[0040] Example 2

[0041] Example 1 is basically the same, but you need to pay attention to n 铼 :n 硼 :n 硫 =1:1:1, the product mass is 0.15g.

[0042] Electrocatalytic performance of the obtained sample: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 196 mV, 202 mV, and 184 mV, respectively, and the current density reached 10 mA cm -2 And after 25 hours of operation, its catalytic performance has hardly declined.

[0043] Example 3

[0044] Example 1 is basically the same, but you need to pay attention to n 铼 :n 硼 :n 硫 =1:5:1, the product mass is 0.186g.

[0045] Electrocatalytic performance of the obtained sample: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 153 mV, 179 mV, and 166 mV, respectively, and the current density reached 10 mA cm -2 And after 15 hours of operation, its catalytic performance has hardly declined.

[0046] Example 4

[0047] Example 1 is basically the same, but you need to pay attention to n 铼 :n 硼 :n 硫 =1:2:0.4, the product mass is 0.18g.

[0048] Electrocatalytic performance of the obtained sample: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 307 mV, 324 mV, and 377 mV, respectively, and the current density reached 10 mA cm -2 And after 35 hours of operation, its catalytic performance has almost no attenuation, which shows that the amount of sulfur doping has a certain influence on the catalyst performance.

[0049] Example 5

[0050] Example 1 is basically the same, but you need to pay attention to n 铼 :n 硼 :n 硫 =1:2:2, the product mass is 0.19g.

[0051] Electrocatalytic performance of the obtained sample: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 149 mV, 162 mV, and 144 mV, respectively, and the current density reached 10 mA cm -2 And after 25 hours of operation, its catalytic performance has hardly declined.

[0052] Example 6

[0053] Example 1 is basically the same, except that it should be noted that the calcination temperature in the tubular furnace is 650° C. and the product mass is 0.18 g.

[0054] Electrocatalytic performance of the obtained sample: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 189 mV, 206 mV, and 214 mV, respectively, and the current density reached 10 mA cm -2 And after 30 hours of operation, its catalytic performance has hardly declined.

[0055] Example 7

[0056] Example 1 is basically the same, except that the calcination temperature in the tubular furnace is 800° C. and the mass of the product is 0.18 g.

[0057] Electrocatalytic performance of the obtained samples: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 155 mV, 179 mV, and 165 mV, respectively, and the current density reached 10 mA cm -2 And after 30 hours of operation, its catalytic performance has hardly declined.

[0058] Example 8

[0059] Example 1 is basically the same, except that the rhenium source is replaced with rhenium dioxide, and the product mass is 0.218 g.

[0060] Electrocatalytic performance of the obtained samples: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 147 mV, 159 mV, and 152 mV, respectively, and the current density reached 10 mA cm -2 And after 35 hours of operation, its catalytic performance has hardly declined.

[0061] Example 9

[0062] Example 1 is basically the same, except that the rhenium source is replaced with ammonium rhenate, and the mass of the product is 0.26 g.

[0063] Electrocatalytic performance of the obtained sample: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 142 mV, 164 mV, and 144 mV, respectively, and the current density reached 10 mA cm -2 And after 30 hours of operation, its catalytic performance has hardly declined.

[0064] Example 10

[0065] Example 1 is basically the same, except that the boron source is replaced with sodium borohydride, and the mass of the product is 0.18 g.

[0066] Electrocatalytic performance of the obtained sample: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 153 mV, 157 mV, and 164 mV, respectively, and the current density reached 10 mA cm -2 And after 30 hours of operation, its catalytic performance has hardly declined.

[0067] Example 11

[0068] Example 1 is basically the same, except that the boron source is replaced with boron trichloride, and the mass of the product is 0.18 g.

[0069] Electrocatalytic performance of the obtained samples: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 141 mV, 155 mV, and 174 mV, respectively, and the current density reached 10 mA cm -2 And after 30 hours of operation, its catalytic performance has hardly declined.

[0070] Example 12

[0071] Example 1 is basically the same, except that the sulfur source is replaced with thiourea, and the mass of the product is 0.18 g.

[0072] Electrocatalytic performance of the obtained samples: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 147 mV, 159 mV, and 180 mV, respectively, and the current density reached 10 mA cm -2 And after 30 hours of operation, its catalytic performance has hardly declined.

[0073] Example 13

[0074] Example 1 is basically the same, except that the sulfur source is replaced with thioacetamide, and the mass of the product is 0.18 g.

[0075] Electrocatalytic performance of the obtained sample: The hydrogen evolution polarization curves measured under the conditions of 1.0 M PBS, 0.5 M H2SO4, and 1.0 M KOH were 162 mV, 179 mV, and 191 mV, respectively, and the current density reached 10 mA cm -2 And after 35 hours of operation, its catalytic performance has hardly declined.

[0076] The above-mentioned embodiments are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes, replacements and improvements that can be easily thought of by technicians familiar with this technical field within the spirit and principles of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a S anion-modified ReB2 catalyst, characterized in that: First, a rhenium source, a boron source and a sulfur source are uniformly mixed and fully ground to obtain a mixture A; then sodium chloride and potassium chloride are uniformly mixed with the mixture A and fully ground again to obtain a mixture B; the mixture B is calcined at high temperature in an Ar gas environment; after calcination, the temperature is cooled to room temperature, and the obtained product is placed in deionized water and fully stirred for cleaning. After removing the supernatant, the obtained precipitate is washed with ethanol, the precipitate is collected by centrifugation, and dried to obtain a S anion-modified ReB2 catalyst; wherein the molar ratio of the rhenium source, the boron source and the sulfur source is 1:1~5:0.4~2; the molar ratio of the sodium chloride to the potassium chloride is 1:1~2; the molar ratio of the rhenium source to the sodium chloride is 1:30~40; the high-temperature calcination temperature is 650~1000℃, the high-temperature calcination time is 120~195 min, and the heating rate during the high-temperature calcination is 3~6℃min -1 The sulfur source is one or a mixture of sulfur powder, thiourea, thioacetamide, and mercaptans; the rhenium source is one or a mixture of rhenium powder, rhenium dioxide, and ammonium rhenate; and the boron source is one or a mixture of amorphous boron powder, sodium borohydride, and boron trichloride.

2. The method for preparing a S anion-modified ReB2 catalyst according to claim 1, wherein: The product obtained by cooling to room temperature after calcination is placed in 70~90℃ deionized water and stirred thoroughly for 15~30 minutes.

3. A S anion-modified ReB2 catalyst, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 or 2.

4. Use of the S anion-modified ReB2 catalyst according to claim 3 in electrocatalytic water splitting to produce hydrogen over a wide pH range.

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