阅读说明：本技术 一种中空纳米电解水用阴极催化剂及其制备方法 (Cathode catalyst for hollow nano electrolyzed water and preparation method thereof ) 是由 冯永强 董沛沛 黄剑锋 曹丽云 王潇 冯伟航 陈俊生 王海 于 2020-06-22 设计创作，主要内容包括：本发明提供一种中空纳米电解水用阴极催化剂及其制备方法,所述方法包括如下步骤：步骤1,向钴盐和柠檬酸钠的混合溶液中加入铁氰化钾后静置,钴盐和铁氰化钾的摩尔比为(0.1-1)：(0.2-0.5),所得的产物经分离后依次洗涤、干燥,得到类普鲁士蓝化合物；步骤2,按(0.2-0.4)：(1-2)的质量比,将类普鲁士蓝化合物和NaH<Sub>2</Sub>PO<Sub>2</Sub>在保护气体下进行退火处理,得到中空纳米电解水用阴极催化剂。本发明反应受热均匀,操作简单易行、易控制,所使用原料成本低、易得到目标产物,制得的催化剂为中空结构,具有优异的电催化活性及阴极反应稳定性。(The invention provides a cathode catalyst for hollow nano electrolyzed water and a preparation method thereof, wherein the method comprises the following steps: step 1, adding potassium ferricyanide into a mixed solution of cobalt salt and sodium citrate, and standing, wherein the molar ratio of the cobalt salt to the potassium ferricyanide is (0.1-1): (0.2-0.5), separating the obtained product, and then sequentially washing and drying to obtain a prussian blue analogue compound; step 2, according to (0.2-0.4): (1-2) the Prussian-like blue compound and NaH are mixed according to the mass ratio 2 PO 2 And carrying out annealing treatment under protective gas to obtain the cathode catalyst for the hollow nano-electrolyzed water. The invention has the advantages of uniform reaction heating, simple and easy operation, easy control, low cost of used raw materials, easy obtainment of target products, hollow structure of the prepared catalyst, excellent electrocatalytic activity and excellent cathode reaction stability.)

1. A preparation method of a cathode catalyst for hollow nano-electrolyzed water is characterized by comprising the following steps:

step 1, adding potassium ferricyanide into a mixed solution of cobalt salt and sodium citrate, and standing, wherein the molar ratio of the cobalt salt to the potassium ferricyanide is (0.1-1): (0.2-0.5), separating the obtained product, and then sequentially washing and drying to obtain a prussian blue analogue compound;

step 2, according to (0.2-0.4): (1-2) the Prussian-like blue compound and NaH are mixed according to the mass ratio₂PO₂And carrying out annealing treatment under protective gas to obtain the cathode catalyst for the hollow nano-electrolyzed water.

2. The method for preparing the cathode catalyst for hollow nano-electrolyzed water according to claim 1, wherein in the step 1, the molar ratio of the cobalt salt to the sodium citrate is (0.1-1): (0.5-2).

3. The method for preparing the cathode catalyst for hollow nano-electrolyzed water according to claim 1, wherein the cobalt salt in the step 1 is one or more of cobalt chloride, nitrate, sulfate and acetate.

4. The method for preparing the cathode catalyst for hollow nano-electrolyzed water according to claim 1, wherein in the step 1, the mixed solution is added with potassium ferricyanide and then is kept stand for 20-48 h.

5. The preparation method of the cathode catalyst for hollow nano-electrolyzed water according to claim 1, wherein in the step 1, potassium ferricyanide is added into a mixed solution of cobalt salt, stannous chloride and sodium citrate and then the mixed solution is kept stand, wherein the molar ratio of the cobalt salt to the stannous chloride is (0.1-1): (0.1-1).

6. The method as claimed in claim 1, wherein the annealing in step 2 is performed at 200-500 ℃.

7. The method for preparing a cathode catalyst for hollow nano-electrolyzed water according to claim 1, wherein in the step 2, the annealing is performed for 1 to 3 hours.

8. The method for preparing a cathode catalyst for hollow nano-electrolyzed water according to claim 1, wherein the separated product is washed with deionized water and absolute ethanol in step 1.

9. A cathode catalyst for hollow nano-electrolyzed water obtained by the method for producing a cathode catalyst for hollow nano-electrolyzed water according to any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of electrocatalysis, in particular to a cathode catalyst for hollow nano electrolyzed water and a preparation method thereof.

Background

Prussian Blue Analogue (PBA) has been discovered as early as 1704 and is one of the oldest and simplest metal-organic framework compounds. Due to the wide application of the catalyst in the fields of gas adsorption, energy storage, catalysis, medicine carrying and the like, the catalyst is widely concerned and researched.

The Prussian-blue-like compound is a supermolecular structure formed by self-assembly connection of transition metal central ions serving as metal joints and cyanide radical ligands serving as organic connectors. The transition metal exists in two different positions adjacent to the carbon atom and the nitrogen atom, respectively, in the framework structure of the prussian blue, and the two positions can be occupied by different metal ions. These metal elements include transition metals such as iron, cobalt, nickel, zinc, and copper. Furthermore, a small amount of noble metal ions can be used to replace the transition metal at the transition metal ion position in the framework structure, while still ensuring that the framework structure of the prussian-like blue remains unchanged.

The transition metal phosphide is also a catalyst widely used in hydrogen evolution, is a cathode catalyst for water electrolysis, and has performance even exceeding that of corresponding transition metals and alloys. The Prussian blue-like compound and the phosphorus source precursor can be used for preparing the transition metal phosphide with excellent performanceElectrocatalysts, such as CoFe-PBA, but prior methods synthesized transition metal phosphide electrocatalysts at 10mA/cm²The disadvantages of higher overpotential are present, and there is a need for improvement in their synthesis.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides the cathode catalyst for the hollow nano-electrolyzed water and the preparation method thereof, the reaction is heated uniformly, the operation is simple and easy to control, the used raw materials are low in cost, the target product is easy to obtain, and the prepared catalyst is of a hollow structure and has excellent electrocatalytic activity and cathode reaction stability.

The invention is realized by the following technical scheme:

a preparation method of a cathode catalyst for hollow nano-electrolyzed water comprises the following steps:

step 1, adding potassium ferricyanide into a mixed solution of cobalt salt and sodium citrate, and standing, wherein the molar ratio of the cobalt salt to the potassium ferricyanide is (0.1-1): (0.2-0.5), separating the obtained product, and then sequentially washing and drying to obtain a prussian blue analogue compound;

step 2, according to (0.2-0.4): (1-2) the Prussian-like blue compound and NaH are mixed according to the mass ratio₂PO₂And carrying out annealing treatment under protective gas to obtain the cathode catalyst for the hollow nano-electrolyzed water.

Preferably, in step 1, the molar ratio of the cobalt salt to the sodium citrate is (0.1-1): (0.5-2).

Preferably, the cobalt salt in step 1 is one or more of cobalt chloride, nitrate, sulfate and acetate.

Preferably, in the step 1, the mixed solution is added with potassium ferricyanide and then is kept stand for 20-48 h.

Preferably, in the step 1, potassium ferricyanide is added into the mixed solution of cobalt salt, stannous chloride and sodium citrate and then the mixture is kept stand, wherein the molar ratio of the cobalt salt to the stannous chloride is (0.1-1): (0.1-1).

Preferably, in step 2, the annealing is performed at 200-500 ℃.

Preferably, in step 2, the annealing is performed for 1 to 3 hours.

Preferably, step 1 washes the isolated product with deionized water and absolute ethanol.

A cathode catalyst for hollow nano-electrolyzed water obtained by the method for preparing a cathode catalyst for hollow nano-electrolyzed water as set forth in any one of the above.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention relates to a preparation method of a cathode catalyst for hollow nano-electrolyzed water, which comprises the steps of firstly carrying out precipitation reaction on cobalt salt, sodium citrate and potassium ferricyanide to obtain a Prussian-blue-like compound, and then annealing the Prussian-blue-like compound and a phosphorus source precursor together to prepare a transition metal phosphide electrocatalyst with excellent performance. After annealing, the nano particles are mutually aggregated and tightly connected to form a large specific surface area, so that more electrochemical active sites and a larger contact area with electrolyte can be provided, and the catalytic performance is improved; the hollow structure can accelerate the transmission of electrons and ions and effectively relieve the problem of volume expansion caused by the circulation shuttle of the ions; so that the composite material shows high electrocatalytic activity, excellent HER performance of electrolyzed water and excellent stability.

Furthermore, the CoSnFe-PBA with the hollow structure has good appearance, is easy to regulate and control, has excellent electrocatalytic hydrogen production performance, and is added with Sn relative to PBA cubic nanometer materials²⁺Through NaH₂PO₂The hollow corner-cut polyhedron PBA obtained by annealing has larger specific surface area and exposes more active sites, so that the hollow corner-cut polyhedron PBA has more excellent electrocatalytic activity and excellent electrolyzed water HER performance.

Drawings

FIG. 1 is an XRD pattern of CoFe-PBA and CoSnFe-PBA prepared in example 1 of the present invention;

FIG. 2 is the XRD patterns of CoFeP-PBA and CoSnFeP-PBA prepared in example 1 of the present invention;

FIG. 3 is an SEM representation of CoFe-PBA prepared in example 1 of the present invention;

FIG. 4 is an SEM representation of CoSnFe-PBA prepared in example 1 of the present invention;

FIG. 5 is an SEM representation of CoFeP-PBA prepared in example 1 of the present invention;

FIG. 6 is an SEM representation of CoSnFeP-PBA prepared in example 1 of the present invention;

FIG. 7 is the LSV curve of CoFe PBA, CoSnFe PBA, CoFeP-PBA and CoSnFeP-PBA prepared in example 1 of the present invention in 1M KOH electrolyte.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

The invention relates to a preparation method of a cathode catalyst for hollow nano-electrolyzed water, which comprises two schemes, and specifically comprises the following steps:

the first scheme is as follows:

weighing 0.1-1mmol of cobalt salt and 0.5-2mmol of sodium citrate dihydrate, wherein the cobalt metal salt can be one or more of cobalt chloride hexahydrate, nitrate, sulfate and acetate, and because the proportion is not required and the effects are the same, the following examples only take each pure substance, dissolving the pure substances in 10-30mL of deionized water, adding a potassium ferricyanide aqueous solution while stirring, uniformly mixing the potassium ferricyanide aqueous solution by dissolving 0.2-0.5mmol of potassium ferricyanide in 10-30mL of deionized water, continuously stirring for 5-30min to obtain a mixed solution, standing for 20-48h, centrifuging the product, washing the product with deionized water and absolute ethyl alcohol, drying in vacuum, and synthesizing a CoFe-PBA cube by a precipitation method.

Weighing 200-400mg CoFe-PBA cubes, placing in a small crucible, and weighing 1-2g NaH₂PO₂Placing the crucible into a large crucible, placing a small crucible into the large crucible, introducing helium as protective gas, reacting for 1-3h at 500 ℃ by adopting an annealing method, and utilizing NaH₂PO₂Etching of CoFe-PBA cubes, i.e. NaH₂PO₂Generating pH at high temperature₃And phosphorizing the CoFe-PBA cube to obtain a hollow nano CoFe-PBA cube, namely the cathode catalyst for electrolyzing water.

The second scheme is as follows:

weighing 0.1-1mmol of cobalt metal salt, 0.1-1mmol of stannous chloride and 0.5-2mmol of sodium citrate dihydrate, wherein the cobalt metal salt can be one or more of cobalt chloride hexahydrate, nitrate, sulfate and acetate, dissolving in 10-30mL of deionized water, adding a potassium ferricyanide aqueous solution while stirring, dissolving the potassium ferricyanide aqueous solution in 10-30mL of deionized water by 0.2-0.5mmol of potassium ferricyanide, uniformly mixing, continuously stirring for 5-30min to obtain a mixed solution, standing for 20-48h, centrifuging, washing and drying the product, and synthesizing to obtain the CoSnFe-PBA corner cut polyhedron by a precipitation method.

Weighing 200-400mg CoSnFe-PBA corner-cut polyhedron, placing in a small crucible, and weighing 1-2g NaH₂PO₂Placing the crucible into a large crucible, placing a small crucible into the large crucible, introducing helium as protective gas, reacting for 1-3h at 500 ℃ by adopting an annealing method, and utilizing NaH₂PO₂Etching CoSnFe-PBA cubes, i.e. NaH₂PO₂Generating pH at high temperature₃And phosphorizing the CoSnFe-PBA cube to obtain a hollow nano CoSnFe-PBA corner-cut polyhedron, namely the cathode catalyst for electrolyzing water.

The invention adopts an annealing method to chemically etch CoFe-PBA cube and CoSnFe-PBA corner-cut polyhedral structure to form a nano cube and a corner-cut polyhedral structure with hollow structures, and the structure is opposite to that without Sn²⁺The PBA cubic nanometer material is prepared by adding Sn²⁺And the hollow corner-cut polyhedron PBA obtained by annealing has larger specific surface area and exposes more active sites, so that the hollow corner-cut polyhedron PBA has more excellent electrocatalytic activity and excellent electrolyzed water HER performance.

The invention is illustrated in more detail below by means of specific examples: