CN113026049A

CN113026049A - Two-step solvothermal method for preparing NiFe (CN)5NO-Ni3S2-NF composite catalyst and application thereof

Info

Publication number: CN113026049A
Application number: CN202110195941.5A
Authority: CN
Inventors: 沈小平; 范晨; 季振源
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2021-02-22
Filing date: 2021-02-22
Publication date: 2021-06-25
Anticipated expiration: 2041-02-22
Also published as: CN113026049B

Abstract

本发明属于纳米复合材料技术领域，涉及电解水析氧催化剂，特别涉及二步法制备NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂，包括：配制质量百分比浓度为1～5 mg mL^‑1的硫脲去离子水溶液，移入反应釜中，浸入经预处理的泡沫镍，120～180℃水热反应3～10 h，自然冷却至室温，取出后用去离子水洗净，60℃真空干燥12h，得到Ni₃S₂/NF；按固液比100～300mg:20 mL的比例，将Na₂Fe(CN)₅NO•2H₂O完全溶于乙二醇中，移入反应釜，再加入Ni₃S₂/NF，200℃溶剂热反应6～12 h，冷却至室温，取出，去离子水洗净，60℃真空干燥12h，即得。本发明合成方法简单易行、成本低、适合大规模生产。得益于Ni₃S₂和NiFe(CN)₅NO之间的协同效应以及NF载体的优异特性，催化剂表现出优异的OER电催化活性和稳定性，有望在电解水中实际应用。

The invention belongs to the technical field of nano-composite materials, relates to an oxygen evolution catalyst for electrolysis of water, and particularly relates to the preparation of a NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst by a two-step method, comprising: preparing a mass percentage concentration of 1-5 mg mL ^‑1 deionized aqueous solution of thiourea was transferred into the reaction kettle, immersed in the pretreated nickel foam, hydrothermally reacted at 120～180℃ for 3～10 h, cooled to room temperature naturally, taken out and washed with deionized water, 60℃ Vacuum dry for 12 hours to obtain Ni ₃ S ₂ /NF; according to the ratio of solid-liquid ratio of 100-300 mg: 20 mL, Na ₂ Fe(CN) ₅ NO•2H ₂ O was completely dissolved in ethylene glycol, transferred to the reaction kettle, Then add Ni ₃ S ₂ /NF, solvothermally react at 200°C for 6-12 hours, cool to room temperature, take out, wash with deionized water, and vacuum dry at 60°C for 12 hours. The synthesis method of the invention is simple and feasible, has low cost and is suitable for large-scale production. Benefiting from the synergistic effect between Ni ₃ S ₂ and NiFe(CN) ₅ NO and the excellent properties of NF supports, the catalyst exhibits excellent OER electrocatalytic activity and stability, and is expected to be practical in water electrolysis.

Description

Two-step solvothermal method for preparing NiFe (CN)5NO-Ni3S2-NF composite catalyst and application thereof

Technical Field

The invention belongs to the technical field of nano composite material preparation, relates to an electrolytic water oxygen evolution catalyst, and particularly relates to a two-step method for preparing NiFe (CN)₅NO-Ni₃S₂NF (i.e. NiFe (CN))₅NO/Ni₃S₂/NF) composite catalyst and application thereof.

Background

In recent years, as the human society has been developed to depend on fossil fuels excessively, there are many problems that human beings have to pay attention to, such as environmental pollution and CO generation by using fossil fuels₂Resulting in greenhouse effect, etc. Most importantly, fossil fuels are non-renewable energy sources, and with the excessive exploitation and use of human beings, the storage of fossil fuels is also becoming exhausted. On the other hand, common renewable energy sources such as wind energy, solar energy, tidal energy, geothermal energy, and the like cannot be widely applied due to factors such as the need for a special geographical environment.

The hydrogen energy is used as a pollution-free clean energy and has a very good application prospect in the fields of fuel cells and the like. There are many methods for producing hydrogen, and among them, the electrolysis of water to produce hydrogen is enthusiastic to researchers because of its simple process. The hydrogen production process by water electrolysis comprises two aspects: anodic Oxygen Evolution Reaction (OER) and cathodic Hydrogen Evolution Reaction (HER). In general, the two reactions have slower kinetic characteristics, require higher voltage for driving, and consume a large amount of electric energy. In order to solve the above problems, researchers need to develop an efficient electrocatalyst to reduce the reaction barrier and thus the driving voltage required for the reaction.

The current common commercial catalysts are noble metal-based catalysts such as Pt, Ru and Ir, are expensive and have scarce resource reserves on the earth, so that the wide application of the catalysts in the industry is limited. Therefore, it is necessary to develop a highly efficient and stable non-noble metal-based catalyst (such as transition metal-based catalyst of Fe, Co, Ni, etc.) instead of noble metal-based catalyst.

In recent years, transition metal compounds (such as oxides, borides, nitrides, sulfides, phosphides, etc.) of Fe, Co and Ni have been studied as alkaline electrolytic water catalysts because of their advantages such as structural diversity and low cost. Among them, transition metal sulfides are considered to be promising electrolytic water catalyst materials due to their higher electrical conductivity. In addition, the preparation of electrolytic water catalyst materials using Metal Organic Frameworks (MOFs) has been explored because of their advantages such as high specific surface area, special metal active sites and porosity.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to disclose a two-step solvothermal method for preparing NiFe (CN)₅NO/Ni₃S₂a/NF composite catalyst.

The invention uses foam Nickel (NF) with large specific surface area, good conductivity and high mechanical strength as a catalyst carrier and serves as a nickel source; the Ni is obtained by sulfurizing NF by hydrothermal method using non-toxic thiourea as sulfur source₃S₂/NF; then adding Na₂Fe(CN)₅NO•2H₂O solvothermal method for Ni in ethylene glycol solution₃S₂Ion exchange of/NF to synthesize Ni loaded on foam nickel without binder₃S₂And NiFe (CN)₅NO composite catalyst (expressed as NiFe (CN))₅NO/Ni₃S₂/NF）。

Technical scheme

Two-step solvothermal method for preparing NiFe (CN)₅NO/Ni₃S₂the/NF composite catalyst comprises the following steps:

(1) the prepared mass percentage concentration is 1-5 mg mL^-1Preferably 2.5mg mL^-1The thiourea deionized water solution is moved into a reaction kettle, the pretreated foam nickel is completely immersed, hydrothermal reaction is carried out for 3-10 h at 120-180 ℃, preferably reaction is carried out for 5 h at 150 ℃, natural cooling is carried out to room temperature, the solution is taken out and washed by deionized water, vacuum drying is carried out for 12h at 60 ℃, and Ni is obtained₃S₂/NF；

(2) And according to the solid-liquid ratio of 100-300 mg:20 mL, preferably 200 mg:20 mL of Na₂Fe(CN)₅NO•2H₂And O is completely dissolved in ethylene glycol, transferred into a reaction kettle, and mixed according to the solid-liquid ratio of 200 mg:20 mL of Ni₃S₂/NF, carrying out solvothermal reaction at 200 ℃ for 6-12 h, preferably at 200 ℃ for 9 h, cooling to room temperature, taking out, washing with deionized water, and vacuum drying at 60 ℃ for 12h to obtain NiFe (CN)₅NO/Ni₃S₂a/NF composite catalyst.

In a preferred embodiment of the present invention, the pretreated nickel foam comprises the following steps: soaking commercial nickel foam in 6M HCl for over 30min to remove surface oxides and impurities, and allowing the treated nickel foam to directly serve as a nickel source to participate in the reaction.

Ni produced by the invention₃S₂Ni in/NF₃S₂The nano-sheet array is closely attached to the surface of the foam nickel, and the final product is a rod-shaped NiFe (CN) assembled by nano-sheets₅NO-Ni₃S₂Attached to the surface of the nickel foam.

NiFe (CN) prepared by the invention₅NO/Ni₃S₂the/NF has a rod-shaped appearance formed by combining nano sheets, can provide more active sites, has lower electrochemical impedance to participate in electrochemical catalytic reaction, and can be applied to oxygen evolution reaction electrode catalysts.

Oxygen evolution experiment:

the obtained NiFe (CN)₅NO/Ni₃S₂/NF shear area of 1 × 1 cm²The piece of (a) was used as a working electrode, a saturated silver/silver chloride electrode was used as a reference electrode, a carbon rod was used as a counter electrode, and a CV curve graph was measured in a 1M KOH solution using an electrochemical workstation (chenhua 760E).

As an oxygen evolution reaction electrode catalytic material, the excellent performance is shown to have lower initial over potential and smaller Tafel slope, and the current density is 10 mA cm in general^-2Overpotential of time is used as a measure. Discovery with NiFe (CN)₅NO/NF、Ni₃S₂comparative/NF, NiFe (CN)₅NO/Ni₃S₂the/NF has more excellent catalytic performance in oxygen evolution reaction, obviously reduced over potential and Tafel slope and good stability.

Reagents and raw materials used: na (Na)₂Fe(CN)₅NO•2H₂O (sodium nitrosoferricyanide), shanghai chemical agents ltd; HCl (hydrochloric acid), national chemical agents ltd; CN₂H₄S (thiourea), national chemical reagents ltd; (CH)₂OH)₂(ethylene glycol), national chemical agents, ltd; KOH (potassium hydroxide), national chemical agents ltd; are all analytically pure; nickel Foam (NF), chandeli new materials ltd.

Advantageous effects

Firstly, the foamed nickel is vulcanized to obtain Ni₃S₂/NF; then using solvothermal method to make Ni₃S₂/NF and Na₂Fe(CN)₅Ion exchange of NO to NiFe (CN)₅NO/Ni₃S₂/NF oxygen evolution catalyst. The catalytic performance of the catalyst is higher than that of the commercial noble metal catalyst IrO₂More excellent. The synthetic method is simple and feasible, has low cost and is suitable for large-scale production, and the prepared NiFe (CN)₅NO/Ni₃S₂The NF electrolyzed water oxygen evolution catalyst has excellent performance and very high popularization and application values. Benefit from Ni₃S₂And NiFe (CN)₅The synergistic effect of NO and the excellent characteristics of the NF carrier show excellent OER electrocatalytic activity and stability, and are expected to play a role in the practical application of water electrolysis.

Drawings

FIG. 1 NiFe (CN) prepared in example 1₅NO/Ni₃S₂X-ray diffraction (XRD) pattern of/NF composite material;

FIG. 2 NiFe (CN) prepared in example 1₅NO/Ni₃S₂A field emission Scanning Electron Microscope (SEM) picture of the/NF composite material;

FIG. 3 NiFe (CN) prepared in example 1₅NO/Ni₃S₂Energy spectrum (EDS) diagram of the/NF composite, wherein the abscissa is energy in Ke V and the ordinate is intensity in cps;

FIG. 4 NiFe (CN) prepared in examples 1 to 5₅NO/Ni₃S₂CV half-curve diagram of the/NF composite measured in a 1M KOH solutionThe test temperature is 25 ℃, after full activation by cyclic voltammetry scanning for 100 circles, the voltage range is 0-0.7V (Vvs Ag/AgCl) was subjected to CV curve test at a sweep rate of 5 mV s^-1. The abscissa is voltage in units of V; the ordinate is the current density in mA cm^-2；

FIG. 5 NiFe (CN) prepared in example 1₅NO/Ni₃S₂Tafel graph of/NF composite material as electrolyzed water oxygen evolution catalyst in 1M KOH solution, wherein the abscissa is current density (unit is mA cm)^-2) The logarithm of (d); the ordinate is the overpotential in V;

FIG. 6 NiFe (CN) prepared in example 1₅NO/Ni₃S₂the/NF composite material is used as an electrolytic water oxygen evolution catalyst and is in the electrolyte of 1M KOH at 10 mA cm^-2In which the abscissa is time in h and the ordinate is voltage in V, the voltage is plotted against time in 17 h.

Detailed Description

The present invention will be described in detail below with reference to examples to enable those skilled in the art to better understand the present invention, but the present invention is not limited to the following examples.

Example 1

Adding 200 mg of Na₂Fe(CN)₅NO•2H₂Dissolving O in 20mL of ethylene glycol, stirring for 30min, putting the solution into a 30 mL reaction kettle liner, and then adding Ni₃S₂the/NF is also put into the reaction kettle and reacts in an oven at the temperature of 200 ℃ for 9 hours. After the reaction is finished, washing the nickel foam with deionized water for a plurality of times, then putting the reacted nickel foam into a vacuum oven to be dried at 60 ℃, and finally obtaining NiFe (CN)₅NO/Ni₃S₂a/NF composite material.

FIG. 1 is an XRD diagram of the product, in which all diffraction peaks except the signal peak of metallic nickel foam are in a cubic phase of NiFe (CN)₅NO•5H₂Standard card of O (JCPDS, number 43-0772) and Ni in cubic phase₃S₂Is consistent with the standard card (JCPDS, number 44-1418), indicating that the target product NiFe (CN) is successfully prepared₅NO/Ni₃S₂/NF。

FIG. 2 is an SEM image of the product, from which it can be seen that the product NiFe (CN)₅NO/Ni₃S₂the/NF is a rod formed by combining nano sheets and attached to the surface of the foam nickel.

FIG. 3 is the EDS spectrum of the product, the sample contains Fe, Ni, C, N, O and S elements.

As can be seen from the CV half-curve in FIG. 4, NiFe (CN)₅NO/Ni₃S₂/NF Current Density of 10 mA cm^-2The overpotential is 162 mV, has the most excellent performance and the performance is similar to that of commercial IrO₂The comparison is more excellent.

As can be seen from the Tafel curve in FIG. 5, NiFe (CN)₅NO/Ni₃S₂Tafel slope of/NF was 26 mV dec^-1Which shows that it has superior oxygen evolution kinetics.

FIG. 6 is NiFe (CN)₅NO/Ni₃S₂Voltage vs time curves of the NF catalyst in 1M KOH solution. The catalyst was tested for stability at 10 mA cm^-2After the electrolysis is carried out for 17 hours under the constant current density, the good catalytic activity is still kept, which shows that the synthesized material has good stability.

Example 2

Adding 100 mg of Na₂Fe(CN)₅NO•2H₂Dissolving O in 20mL of ethylene glycol, stirring for 30min, putting the solution into a 30 mL reaction kettle liner, and then adding Ni₃S₂the/NF is also put into the reaction kettle and reacts in an oven at the temperature of 200 ℃ for 9 hours. After the reaction is finished, washing the nickel foam with deionized water for a plurality of times, then putting the reacted nickel foam into a vacuum oven for drying at 60 ℃, and finally obtaining NiFe (CN)₅NO/Ni₃S₂a/NF composite material.

Example 3

Adding 300mg of Na₂Fe(CN)₅NO•2H₂Dissolving O in 20mL of ethylene glycol, stirring for 30min, putting the solution into a 30 mL reaction kettle liner, and then adding Ni₃S₂the/NF is also put into the reaction kettle and is reacted in an ovenThe temperature is 200 ℃ and the time is 9 h. After the reaction is finished, washing the nickel foam with deionized water for a plurality of times, then putting the reacted nickel foam into a vacuum oven to be dried at 60 ℃, and finally obtaining NiFe (CN)₅NO/Ni₃S₂a/NF composite material.

Example 4

Adding 200 mg of Na₂Fe(CN)₅NO•2H₂Dissolving O in 20mL of ethylene glycol, stirring for 30min, putting the solution into a 30 mL reaction kettle liner, and then adding Ni₃S₂the/NF is also put into the reaction kettle and reacts in an oven at the temperature of 200 ℃ for 6 hours. After the reaction is finished, washing the nickel foam with deionized water for a plurality of times, then putting the reacted nickel foam into a vacuum oven to be dried at 60 ℃, and finally obtaining NiFe (CN)₅NO/Ni₃S₂a/NF composite material.

Example 5

Adding 200 mg of Na₂Fe(CN)₅NO•2H₂Dissolving O in 20mL of ethylene glycol, stirring for 30min, putting the solution into a 30 mL reaction kettle liner, and then adding Ni₃S₂the/NF is also put into the reaction kettle and reacts in an oven at the temperature of 200 ℃ for 12 hours. After the reaction is finished, washing the nickel foam with deionized water for a plurality of times, then putting the reacted nickel foam into a vacuum oven to be dried at 60 ℃, and finally obtaining NiFe (CN)₅NO/Ni₃S₂a/NF composite material.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present invention or directly or indirectly applied to other related technical fields are included in the scope of the present invention.

Claims

1.二步溶剂热法制备NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂，其特征在于，包括如下步骤：1. NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst prepared by two-step solvothermal method, characterized in that, comprising the following steps:

（1)、配制质量百分比浓度为1～5 mg mL^-1的硫脲去离子水溶液，移入反应釜中，将经预处理的泡沫镍完全浸入，120～180℃水热反应3～10 h，自然冷却至室温，取出后用去离子水洗净，60℃真空干燥12h，得到Ni₃S₂/NF；(1), prepare the thiourea deionized aqueous solution with a mass percentage concentration of 1～5 mg mL ^-1 , transfer it into the reactor, completely immerse the pretreated nickel foam, and perform a hydrothermal reaction at 120～180 ℃ for 3～10 h, Naturally cooled to room temperature, taken out, washed with deionized water, and dried under vacuum at 60 °C for 12 h to obtain Ni ₃ S ₂ /NF;

（2）、按固液比100～300mg：20 mL的比例，将Na₂Fe(CN)₅NO•2H₂O完全溶于乙二醇中，移入反应釜中，再按照固液比200 mg：20mL的比例，加入Ni₃S₂/NF，200℃溶剂热反应6～12 h，冷却至室温，取出，用去离子水洗净，60℃真空干燥12h，即得。(2) According to the ratio of solid-liquid ratio of 100～300mg: 20 mL, completely dissolve Na ₂ Fe(CN) ₅ NO·2H ₂ O in ethylene glycol, transfer it into the reaction kettle, and then according to the solid-liquid ratio of 200 mg : 20mL, add Ni ₃ S ₂ /NF, solvothermally react at 200°C for 6-12 hours, cool to room temperature, take out, wash with deionized water, and vacuum dry at 60°C for 12 hours.

2.根据权利要求1所述二步溶剂热法制备NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂，其特征在于：步骤（1）中所述配制质量百分比浓度为2.5mg mL^-1的硫脲去离子水溶液。2. NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst prepared by two-step solvothermal method according to claim 1, characterized in that: the preparation mass percentage concentration described in step (1 ⁾ is 2.5mg mL- ¹ of thiourea in deionized water.

3.根据权利要求1所述二步溶剂热法制备NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂，其特征在于：步骤（1）中所述150℃水热反应5 h。3 . The NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst prepared by the two-step solvothermal method according to claim 1, characterized in that: the hydrothermal reaction at 150°C in step (1) is 5 h.

4.根据权利要求1所述二步溶剂热法制备NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂，其特征在于：步骤（1）中所述经预处理的泡沫镍，其处理步骤为将商品泡沫镍用6 M HCl浸泡超声30min以上，除去其表面氧化物及杂质，处理后的泡沫镍直接作为镍源参与反应。4. The NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst prepared by the two-step solvothermal method according to claim 1, wherein the pretreated nickel foam in the step (1) is treated with The step is to soak the commercial nickel foam with 6 M HCl for more than 30 minutes to remove the surface oxides and impurities, and the processed nickel foam directly participates in the reaction as a nickel source.

5.根据权利要求1所述二步溶剂热法制备NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂，其特征在于：步骤（2）中所述按固液比200 mg：20 mL的比例，将Na₂Fe(CN)₅NO•2H₂O完全溶于乙二醇中。5. NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst prepared by two-step solvothermal method according to claim 1, characterized in that: as described in step (2), the ratio of solid to liquid is 200 mg: 20 mL The proportion of Na ₂ Fe(CN) ₅ NO•2H ₂ O was completely dissolved in ethylene glycol.

6.根据权利要求1所述二步溶剂热法制备NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂，其特征在于：步骤（2）中所述200℃溶剂热反应9 h。6 . The NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst prepared by the two-step solvothermal method according to claim 1, characterized in that: the solvothermal reaction at 200°C in step (2) is 9 h.

7.根据权利要求1-6任一所述方法制备得到的NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂。7. The NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst prepared according to any one of claims 1-6.

8.根据权利要求7所述NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂，其特征在于：由纳米片组装而成的棒状形貌附着于泡沫镍表面。8 . The NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst according to claim 7 , wherein the rod-shaped morphology assembled from nanosheets is attached to the surface of the nickel foam. 9 .

9.一种如权利要求7或8所述NiFe(CN)₅NO/Ni₃S₂/NF复合催化剂的应用，其特征在于：将其应用于析氧反应电极催化剂。9 . An application of the NiFe(CN) ₅ NO/Ni ₃ S ₂ /NF composite catalyst according to claim 7 or 8, characterized in that: it is applied to an oxygen evolution reaction electrode catalyst.