Iron and phosphorus co-doped Co3S4 hollow polyhedral electrocatalyst as well as preparation method and application thereof

Abstract

The invention relates to an iron and phosphorus co-doped Co3S4 hollow polyhedral electrocatalyst as well as a preparation method and application thereof, and belongs to the technical field of electrocatalysis and new energy materials. The electrocatalyst material provided by the invention adopts a hydrothermal-high temperature phosphating combined preparation method, and the synthesis steps comprise: preparing an iron-doped Co3S4 hollow polyhedral precursor in one step by adopting a hydrothermal reaction, and then carrying out high temperature phosphating to obtain the iron and phosphorus co-doped Co3S4 hollow polyhedral point catalyst material. The prepared electrocatalyst material has the characteristics of anion and cation co-doping and hollow porosity, and the oxygen evolution reaction activity of the electrocatalyst is improved through the synergistic effect of multiple active components such as Fe atoms, P atoms and Co3S4 nanoparticles; the preparation method is low in cost, and the obtained material is high in catalytic activity and good in stability and has wide application prospects in the fields of electrolyzed water, metal-air batteries and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis and new energy materials, and specifically relates to an iron-phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst and a preparation method and application thereof. Background Art

[0002] Environmental pollution and energy crisis require the development of a new generation of energy technologies. Among them, hydrogen produced by water electrolysis is considered to be one of the most anticipated sustainable energy solutions. However, the kinetic characteristics of the oxygen evolution reaction (OER) occurring on the anode of water electrolysis are inherently slow, which greatly hinders the practical application of water electrolysis devices. Precious metal-based electrocatalysts (such as ruthenium oxide or yttrium oxide) provide good OER performance, but the high price and poor stability seriously affect their widespread application in water electrolysis. Therefore, it is imperative to develop efficient OER electrocatalysts. Nowadays, non-precious metal-based catalysts have the highest cost-effectiveness, and more and more people are committed to the development of transition metal-based electrocatalysts, including transition metal oxides, phosphides, sulfides and nitrides. Through a series of reasonable means, such as defect design (cation and anion doping), the electronic structure of the catalyst can be optimized, thereby improving its electrocatalytic performance. At present, many transition metal-based electrocatalysts have catalytic activities comparable to those of precious metal-based catalysts. Although the above research has achieved remarkable results, non-precious metal catalysts are still limited by insufficient active sites and slow reaction kinetics, which affects their application in fields such as water electrolysis or metal-air batteries. Summary of the invention

[0003] In view of the above problems, the present invention provides an iron-phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst and its preparation method and application. The electrocatalyst material involved in the present invention adopts a preparation method combining hydrothermal and high-temperature phosphating, and the steps include firstly preparing an iron-doped Co3S4 hollow polyhedron precursor by hydrothermal reaction, and then obtaining an iron-phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst material by high-temperature phosphating reaction.

[0004] The technical solution adopted by the present invention is specifically as follows:

[0005] (1) 2-methylimidazole and cobalt salt are dissolved in deionized water, and iron salt is dissolved in ethanol. The cobalt salt aqueous solution is slowly added to the 2-methylimidazole solution with continuous stirring. Next, a certain amount of sulfur source is weighed and dissolved in a mixture of ethylene glycol and deionized water in a certain proportion. Then, the precursor solution containing the sulfur source and iron salt is sequentially added to the above-obtained solution;

[0006] (2) pouring the mixed solution obtained in step (1) into a reaction kettle, subjecting it to a hydrothermal reaction at a specific temperature for a certain period of time, and then centrifuging, washing, and drying to obtain an iron-doped Co3S4 hollow polyhedron precursor;

[0007] (3) The phosphorus source is placed upstream of the tube furnace, and the black powder obtained in step (2) is placed downstream. Under an inert atmosphere, the appropriate heating rate, calcination temperature and calcination time are selected to obtain the iron-phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst.

[0008] Wherein, in step (1), the cobalt source includes but is not limited to one or more of cobalt nitrate, cobalt acetate tetrahydrate, cobalt chloride, etc., and its concentration is 0.5 to 6 mmol L -1 The sulfur source includes, but is not limited to, one or more of thioacetamide, sodium sulfide, and thiourea, and its concentration is 3 to 40 mmol L -1 The iron source includes but is not limited to one or more of ferric acetylacetonate, ferric chloride and ferric nitrate, and its concentration is 0.01~3mmol L -1 The molar ratio of the cobalt source, the sulfur source and the iron source is (1-6):(0.5-10):(0.005-0.03).

[0009] Wherein, in step (1), the metal source required for doping includes but is not limited to an iron source, a nickel source, and a manganese source.

[0010] Wherein, in step (2), the hydrothermal temperature is 100 to 250° C. and the hydrothermal time is 5 to 20 hours.

[0011] Wherein, in step (3), the phosphorus source includes but is not limited to sodium hypophosphite, red phosphorus, etc.; the inert atmosphere includes nitrogen, argon, helium; the heating rate is 1-20°C min -1 ; The target temperature is 250-500°C; The holding time is 0.5-6h. The mass ratio of the precursor to the phosphorus source is (1-6):(0.5-10).

[0012] Another aspect of the present invention provides an iron and phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst prepared by the above-mentioned preparation method.

[0013] The present invention also provides the use of the above-mentioned iron and phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst in water electrolysis or metal-air batteries.

[0014] The beneficial effects of the present invention compared with the prior art are as follows:

[0015] The iron and phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst described in the present invention has better oxygen reduction reaction (OER) performance than commercial catalysts under alkaline conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments are briefly introduced below.

[0017] Figure 1 The XRD patterns of the samples prepared in Comparative Example 1, Comparative Example 2, Comparative Example 3 and Example 1 are shown.

[0018] Figure 2 These are SEM images of the samples prepared in Comparative Example 1, Comparative Example 2, Comparative Example 3 and Example 1.

[0019] Figure 3 LSV curves of the samples prepared in Comparative Example 1, Comparative Example 2, Comparative Example 3 and Example 1 in N2-saturated 1M KOH electrolyte and the stability curve of the sample obtained in Example 1.

[0020] Figure 4 The water electrolysis performance and stability of the sample prepared in Example 1 in a 1M KOH electrolyte saturated with N2. DETAILED DESCRIPTION

[0021] The present invention is described in detail below in conjunction with embodiments, but the embodiments of the present invention are not limited thereto. Obviously, the embodiments described below are only partial embodiments of the present invention. For those skilled in the art, other similar embodiments obtained without creative work all fall within the protection scope of the present invention.

[0022] Embodiment 1:

[0023] (1) Under vigorous stirring, 25 ml of 0.06 mol L -1 Slowly add cobalt nitrate hexahydrate to 25 ml of 2.16 mol L -1 After 15 minutes of ultrasound, 30 ml of 0.13 mol / L -1 Thioacetamide solution (20 ml ethylene glycol / 10 ml deionized water mixed solution) was added. Ferric acetylacetonate (0.000075 mol, 0.02648 g) was weighed and added to 3 ml ethanol, stirred and dissolved, and then added to the solution.

[0024] (2) The above solution was poured into a 100 ml hydrothermal autoclave, heated to 180°C, and maintained for 18 hours. After natural cooling, the sample precursor was obtained by centrifugation (washed twice with ethanol and deionized water, 10,000 r / 10 min, respectively) and vacuum drying (60°C, 12 hours).

[0025] (3) Place the sample precursor in the downstream of the tube furnace and sodium hypophosphite in the upstream. Heat treatment (450 °C, 2 h) was performed under nitrogen atmosphere with a heating rate of 5 °C min -1 Then, the mixture was cooled at room temperature to obtain black powder of iron and phosphorus co-doped Co3S4 hollow polyhedron (Fe,P-Co3S4-HS).

[0026] Comparative Example 1:

[0027] The preparation methods of this comparative example are the same as those of Example 1, except that the iron source in step (1) and the phosphorus source (Co3S4-HS) in step (3) are not added.

[0028] Comparative Example 2:

[0029] The preparation methods of this comparative example are the same as those of Example 1, except that the phosphorus source (Fe-Co3S4-HS) obtained in step (3) is not added.

[0030] Comparative Example 3:

[0031] The preparation methods of this embodiment and comparative example 1 are the same, except that the iron source (P-Co3S4-HS) obtained in step (1) is not added.

Claims

1. An iron-phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst, characterized in that: The catalyst is a Co3S4 hollow polyhedron.

2. An iron-phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst, characterized in that: The catalyst is doped with Co3S4 and Fe ions.

3. An iron-phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst, characterized in that: The catalyst is doped with Co3S4 and P ions.

4. A method for preparing an iron-phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst according to claims 1-3, characterized in that The following steps are involved: S1: 2-methylimidazole and cobalt salt are dissolved in deionized water, and iron salt is dissolved in ethanol. Slowly add the aqueous cobalt salt solution to the 2-methylimidazole solution and continue stirring. Next, weigh a certain amount of sulfur source and dissolve it in a mixture of ethylene glycol and deionized water in a certain proportion. Then, the precursor solution containing the sulfur source and iron salt is added to the above solution in sequence; S2: Add the mixed solution obtained in S1 into the reactor, perform hydrothermal reaction at a specific temperature for a certain period of time, and then centrifuge, wash and dry to obtain a black powder precursor; S3: The phosphorus source is placed upstream of the tube furnace, and the black powder obtained in S2 is placed downstream. Under an inert atmosphere, the appropriate heating rate, calcination temperature and calcination time are selected to obtain the iron and phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst.

5. The preparation method according to claim 4, characterized in that: In step S1, the cobalt source includes but is not limited to one or more of cobalt nitrate, cobalt acetate tetrahydrate, cobalt chloride, etc., and its concentration is 0.5-6 mmol L -1 The sulfur source includes, but is not limited to, one or more of thioacetamide, sodium sulfide, and thiourea, and its concentration is 3 to 40 mmol L -1 The iron source includes but is not limited to one or more of ferric acetylacetonate, ferric chloride and ferric nitrate, and its concentration is 0.01~3mmol L -1 The molar ratio of the cobalt source, the sulfur source and the iron source is (1-6):(0.5-10):(0.005-0.03).

6. The preparation method according to claim 4, characterized in that: In step S1, the metal sources required for doping include but are not limited to iron source, nickel source and manganese source.

7. The preparation method according to claim 4, characterized in that: In step S2, the hydrothermal temperature is 100-250° C. and the hydrothermal time is 5-20 hours.

8. The preparation method according to claim 4, characterized in that: In step S3, the phosphorus source includes but is not limited to sodium hypophosphite, red phosphorus, etc.; the inert atmosphere includes nitrogen, argon, and helium; the heating rate is 1-20°C min -1 ; The target temperature is 250-500°C; The holding time is 0.5-6h. The mass ratio of the precursor to the phosphorus source is (1-6):(0.5-10).

9. The iron or phosphorus single-doped and iron and phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst prepared by the preparation method according to any one of claims 4 to 8.

10. Use of the iron and phosphorus co-doped Co3S4 hollow polyhedron electrocatalyst according to claim 9 in water electrolysis and metal-air batteries.

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