阅读说明：本技术 花球状钴铝硫化物的制备方法 (Preparation method of flower-ball-shaped cobalt-aluminum sulfide ) 是由 姜炜 吴方 郭小雪 王宁 郝嘎子 胡玉冰 谈玲华 于 2018-08-20 设计创作，主要内容包括：本发明公开了一种花球状钴铝硫化物催化剂的制备方法。所述方法先在泡沫镍上自生长花球状钴铝前驱体,再利用氢氧化钾刻蚀模板,然后通过直接加入硫化钠,利用水热硫化的手段制备花球状钴铝硫化物。本发明的钴铝硫化物不仅保持了原有前驱体的花球状形貌,而且具有较好的析氧活性,整个反应过程简单,且制备的析氧催化剂活性较好,易于操作,有利于工业化生产。(The invention discloses a preparation method of a flower-ball-shaped cobalt-aluminum sulfide catalyst. The method comprises the steps of firstly, growing a flower-shaped spherical cobalt-aluminum precursor on foamed nickel, etching a template by using potassium hydroxide, and then preparing a flower-shaped spherical cobalt-aluminum sulfide by directly adding sodium sulfide and using a hydrothermal vulcanization method. The cobalt-aluminum sulfide provided by the invention not only maintains the flower-ball shape of the original precursor, but also has good oxygen evolution activity, the whole reaction process is simple, and the prepared oxygen evolution catalyst has good activity, is easy to operate, and is beneficial to industrial production.)

1. The preparation method of the flower-ball-shaped cobalt-aluminum sulfide catalyst is characterized by comprising the following specific steps of:

soaking foamed nickel into a mixed solution of cobalt nitrate, aluminum nitrate, urea and ammonium fluoride, carrying out hydrothermal reaction at 100-150 ℃, washing with water after the reaction is finished, adding a potassium hydroxide solution with the concentration of 3-5 mol/L, taking out, and placing in Na₂And (2) reacting in the S solution at 90-140 ℃, washing with water after the reaction is finished, and drying to obtain the flower-ball-shaped cobalt-aluminum sulfide, wherein the molar ratio of aluminum nitrate to cobalt nitrate is 1: 1 to 4.

2. The method according to claim 1, wherein the concentration of ammonium fluoride is 0.1 to 0.13 mol/L.

3. The method according to claim 1, wherein the concentration of urea is 0.25 to 0.28 mol/L.

4. The method according to claim 1, wherein the concentration of the cobalt nitrate is 0.048 mol/L.

5. The preparation method according to claim 1, wherein the hydrothermal reaction time is 10 to 14 hours.

6. The preparation method according to claim 1, wherein the soaking time of the potassium hydroxide is 8 to 12 hours.

7. The preparation method according to claim 1, wherein the concentration of the sodium sulfide is 7 to 9 mmol/L.

8. The method according to claim 1, wherein said Na is₂The reaction time in the S solution is 8-10 hours.

Technical Field

The invention belongs to the technical field of oxygen evolution catalysts, and relates to a preparation method of a flower-ball-shaped cobalt-aluminum sulfide.

Background

The hydrogen energy is used as a green, environment-friendly and nontoxic clean energy source, and has the advantages of wide source, environmental friendliness, high heat value and the like. Compared with the hydrogen production by photolysis of water, the hydrogen production by fossil fuel, biological hydrogen production and the hydrogen production by high-temperature pyrolysis of water, the hydrogen production by electrolysis of water is regarded as a hydrogen production technology with great development potential due to the advantages of high hydrogen production purity, simple process, high automation degree and wide raw material source. The electrochemical decomposition of water comprises an anodic oxygen evolution process and a cathodic hydrogen evolution process. However, the oxygen evolution process occurring at the anode involves the transfer of electrons and its own higher energy barrier and slower reaction rate, resulting in increased energy consumption and reduced water splitting efficiency. Therefore, in practical applications, it is necessary to reduce the overpotential and develop an efficient and stable oxygen evolution catalyst.

Noble metal oxide catalysts, e.g. RuO₂、IrO₂Although having high catalytic activity, the precious metals are expensive and have low reserves, which limits the scale application. Therefore, alternative RuO was explored₂、IrO₂The oxygen evolution catalyst which is high in efficiency, low in cost and easy to obtain becomes the key of the real large-scale hydrogen production by water electrolysis.

Research shows that the cobalt-based sulfide catalyst has better OER activity in alkaline solution (J.Mater.chem.A., 2017,5, 23361-23368). However, the existing cobalt-based sulfide catalyst has complicated synthesis steps, such as preparing Co (OH) by an electrodeposition method₂Then obtaining Co by adopting a high-temperature calcination method₃O₄And finally with Na₂S is a sulfur source and is hydrothermally vulcanized, but the catalytic performance of the prepared CoS is to be further improved (J.alloys Compd.2017,723, 772-778). In addition, a method for preparing the cobalt sulfide oxygen evolution catalyst by combining hydrothermal and freeze drying by using thioacetamide and glutathione as sulfur sources is reported in documents. The samples prepared by this method required the use of nafion reagent to bind them to the electrode, reducing the catalytic performance (Electrochimica acta.2017,246, 380-390).

Disclosure of Invention

The invention aims to provide a preparation method of a flower-ball-shaped cobalt-aluminum sulfide catalyst, which utilizes a simple alkali etching process to prepare vacancy defects so as to improve the catalytic activity of the oxygen evolution reaction.

In order to achieve the purpose, the invention adopts the following technical scheme:

a process for preparing the flower-ball-shaped Co-Al sulfide catalyst includes preparing the Co-Al precursor with flower-ball structure by hydrothermal method on the basis of foamed Ni, etching Al by strong alkali, and Na₂S is a sulfur source, and a hydrothermal vulcanization method is adopted to prepare the self-supported flower-ball-shaped cobalt-aluminum sulfide oxygen evolution catalyst with high catalytic activity, and the specific steps are as follows:

soaking foamed nickel into a mixed solution of cobalt nitrate, aluminum nitrate, urea and ammonium fluoride, carrying out hydrothermal reaction at 100-150 ℃, washing with water after the reaction is finished, adding a potassium hydroxide solution with the concentration of 3-5 mol/L, taking out, and placing in Na₂And (2) reacting in the S solution at 90-140 ℃, washing with water after the reaction is finished, and drying to obtain the flower-ball-shaped cobalt-aluminum sulfide, wherein the molar ratio of aluminum nitrate to cobalt nitrate is 1: 1 to 4.

Preferably, the concentration of the ammonium fluoride is 0.1-0.13 mol/L.

Preferably, the concentration of the urea is 0.25-0.28 mol/L.

Preferably, the concentration of the cobalt nitrate is 0.048 mol/L.

Preferably, the hydrothermal reaction time is 10-14 hours.

Preferably, the soaking time of the potassium hydroxide is 8-12 hours.

Preferably, the concentration of the sodium sulfide is 7-9 mmol/L.

Preferably, said Na₂The reaction time in the S solution is 8-10 hours.

Compared with the prior art, the invention has the following advantages:

(1) the invention has low cost of raw materials, is convenient for industrialized production, and effectively controls and synthesizes the flower-ball-shaped cobalt-aluminum sulfide oxygen evolution catalyst under mild conditions;

(2) the invention takes the foam nickel as the substrate to prepare the catalyst with self-support, thereby avoiding the influence of using binders such as Nafion and the like on the performance of the catalyst;

(3) the cobalt-aluminum sulfide in the shape of ball of flower prepared by the inventionThe catalyst has good oxygen evolution reaction activity, and can reach 100mA cm under the condition that the electrolyte is KOH with 1mol/L^-2The required overpotential was 315mV, respectively, and the catalyst was operated at a current density of 20mA cm^-2And a constant current test is carried out, the testing time is 24 hours, the overpotential is increased by only 15mV, and good oxygen evolution stability is shown.

Drawings

FIG. 1 is a scanning electron micrograph of a spherical cobalt aluminum precursor (a) and a spherical cobalt aluminum sulfide (b).

FIG. 2 is a high-resolution scanning electron microscope image of cobalt aluminum sulfide in flower ball shape.

FIG. 3 is an EDS spectrum of cobalt aluminum sulfide spherulites.

FIG. 4 is a linear sweep voltammogram of the oxygen evolution catalysts of examples 1, 2, 3 and comparative example 1.

FIG. 5 is a linear sweep voltammogram of the oxygen evolution catalysts of example 1 and comparative example 2.

FIG. 6 is a linear sweep voltammogram of the oxygen evolution catalysts of example 1 and comparative example 3.

FIG. 7 is a graph showing the stability of the oxygen evolution reaction promoted by the flower-ball-shaped cobalt aluminum sulfide oxygen evolution catalyst of example 1.

Detailed Description

The present invention will be described in more detail with reference to the following examples and the accompanying drawings.