CN113388847A - Prussian blue analogue derived metal sulfide/nitrogen-doped carbon electrocatalyst and preparation method and application thereof - Google Patents

Abstract

一种普鲁士蓝类似物衍生的金属硫化物/氮掺杂碳电催化剂及其制备方法和应用。本发明以钴铁普鲁士蓝类似物为模板，通过氨水刻蚀和气相硫化，制备了非贵金属硫化物立方体笼状纳米复合催化剂。所述催化剂具有CoS₂‑FeS₂/氮掺杂碳异质结构，呈立方体孔状结构，具有高的孔隙度和良好的导电性，在碱性介质中具有优异的析氢和析氧电催化活性。优异的催化性能主要归因于氮掺杂碳提高了导电性；CoS₂‑FeS₂/氮掺杂碳异质结构改变了异质界面的电子结构，提升了其导电性，更有利于电子的传导；氮掺杂的碳基质的复合增加了催化剂的稳定性，促进了电子在金属硫化物和碳基质之间的有效转移，大大的提高了材料的电催化性能。A Prussian blue analog-derived metal sulfide/nitrogen-doped carbon electrocatalyst and its preparation method and application. In the present invention, a non-precious metal sulfide cubic cage-shaped nano composite catalyst is prepared by using a cobalt iron Prussian blue analog as a template, through ammonia water etching and gas phase vulcanization. The catalyst has a CoS2 _{- FeS2} /nitrogen-doped carbon heterostructure, a cubic pore-like structure, high porosity and good electrical conductivity, and excellent hydrogen evolution and oxygen evolution electrocatalytic activity in alkaline media . The excellent catalytic performance is mainly attributed to the improved electrical conductivity of nitrogen-doped carbon; the CoS ₂ ‑FeS ₂ /nitrogen-doped carbon heterostructure changes the electronic structure of the heterointerface, improves its electrical conductivity, and is more conducive to the electronic conductivity. Conduction; the recombination of nitrogen-doped carbon matrix increases the stability of the catalyst and promotes the efficient transfer of electrons between the metal sulfide and the carbon matrix, which greatly improves the electrocatalytic performance of the material.

Description

Prussian blue analogue derived metal sulfide/nitrogen-doped carbon electrocatalyst and preparation method and application thereof

The technical field is as follows:

the invention belongs to the field of new energy material technology and electrochemical catalysis, and particularly relates to a Prussian blue analogue-derived metal sulfide/nitrogen-doped carbon electrocatalyst; also relates to a preparation method of the catalyst and the application of the catalyst in the anodic oxygen evolution reaction of electrolyzed water, the cathodic hydrogen evolution reaction of electrolyzed water and the electrocatalysis in full-electrolysis water.

Background art:

the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) are key electrode processes of the electrolytic water technology, but both processes suffer from slow kinetics. The catalyst for HER is Pt and its alloy, and the catalyst for OER is IrO₂And RuO₂However, these precious metals are rare in nature, so it is important to develop a new type of high-efficiency and low-cost electrocatalyst, of which carbon-based non-precious metal catalysts are one of the most likely to replace the above precious metals, and this has attracted much attention.

Prussian blue and analogues thereof are a class of porous crystalline materials, which themselves have high stability and high porosity and are commonly used in high efficiency catalytic and separation processes. The cobalt iron prussian blue analogue is prepared by reacting cobalt nitrate hexahydrate with potassium ferricyanide, can be used as a sacrificial template to prepare a non-noble metal compound-porous carbon composite material by a high-temperature calcination method, and can adjust electronic properties and surface polarity by doping heteroatom so as to improve the electrochemical catalytic activity of the composite material. Currently, N, S, B, P, etc. are the more commonly used doping atoms that can be substituted for some of the sp in the graphite lattice²The carbon atoms are hybridized, the electronic characteristics of the carbon material are changed, and the catalytic activity and the stability of the carbon material are further improved. Although the Prussian blue analogue is taken as a precursor to prepare the porous carbon nano material to achieve certain performance at present, the cobalt-iron Prussian blue analogue is taken as a template and the precursor, ammonia etching and gas phase vulcanization are carried out to prepare the non-noble metal/carbon material cubic nano compound with the metal sulfide/nitrogen-doped carbon heterostructure and the HER and OER double-function electrocatalytic catalyst thereofThe performance study has not been reported in the literature.

The invention takes cobalt iron Prussian blue analogue as a template, and prepares the non-noble metal sulfide cubic cage-shaped nano carbon compound by ammonia etching and gas phase vulcanization. Due to the porous framework structure of the cobalt iron Prussian blue analogue, the non-noble metal sulfide/nitrogen-doped carbon material obtained by ammonia etching and gas phase vulcanization inherits the cubic porous structure. The resulting CoS₂-FeS₂the/NC catalyst has high porosity, good conductivity and catalytic activity, effectively reduces the overpotential of OER and HER, and shows excellent long-term stability. The method has important theoretical and practical significance for developing non-noble metal sulfide heteroatom doped carbon composite electro-catalysts and energy conversion and storage devices.

The invention content is as follows:

in view of the deficiencies of the prior art and the need for research and application in the art, it is an object of the present invention to provide a prussian blue analog derived metal sulfide/nitrogen doped carbon electrocatalyst; namely, CoS is obtained by taking a cobalt-iron Prussian blue analogue as a template and carrying out ammonia etching and gas phase vulcanization on the cobalt-iron Prussian blue analogue₂-FeS₂A nitrogen-doped carbon catalyst; wherein the cobalt iron Prussian blue analogue is marked as CoFe-PBA, CoS₂-FeS₂N-doped carbon catalyst is described as CoS₂-FeS₂/NC；

The second purpose of the invention is to provide a preparation method of a Prussian blue analogue derived metal sulfide/nitrogen doped carbon electrocatalyst, which comprises the following steps:

(a) preparation of CoFe-PBA

Weighing 860mg Co (NO)₃)₂·6H₂Dissolving O and 1.32g of sodium citrate in 100mL of deionized water, and marking as a solution A; weighing 658mg of potassium ferricyanide and dissolving the potassium ferricyanide into another 100mL of deionized water, and marking as a solution B; adding the solution B into the solution A under the condition of stirring, stirring for three minutes, standing for 10 hours, centrifuging to collect a sample, washing with ionized water and absolute ethyl alcohol for three times respectively, and drying at 50 ℃ for 12 hours;

(b)CoS₂-FeS₂preparation of/NC

Dispersing 20mg of Co-Fe PBA in 50mL of ethanol, adding the Co-Fe PBA into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifugally collecting a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain a cobalt-iron nano-framework which is marked as CoFe-NFs; weighing 20mg of CoFe-NFs in a magnetic boat, placing the magnetic boat in the lower end of a tube furnace, weighing 200-400 mg of sulfur powder in the magnetic boat, placing the magnetic boat in the upper end of the tube furnace, heating to 200-500 ℃ at the speed of 2 ℃/min, and vulcanizing in a nitrogen atmosphere for 1-5 hours to obtain the catalyst CoS₂-FeS₂/NC；

The metal sulfide/nitrogen-doped carbon electrocatalyst is of a hollow nano cubic cage structure, elements are uniformly distributed on the edges of a cube, and the average particle size of nano cubic cage units of the catalyst is 100-200 nm; metal sulfide CoS₂-FeS₂The average grain diameter of the nano-particles is 5-30nm, and the nano-particles are uniformly embedded on the nitrogen-doped carbon nano-chip.

The invention also aims to provide the catalytic application of the Prussian blue analogue derived metal sulfide/nitrogen-doped carbon electrocatalyst in the electrolysis of water cathode HER and anode OER.

The invention takes cobalt iron Prussian blue analogue as a template, prepares the non-noble metal sulfide cubic cage-shaped nano composite electrocatalyst by ammonia etching and gas phase vulcanization; the heterostructure not only improves the conductivity of the catalyst and increases active sites, but also effectively reduces overpotentials of HER and OER, and shows excellent long-term stability.

Compared with the prior art, the invention has the following main advantages and beneficial effects:

1) the bifunctional electrocatalyst is a non-noble metal composite material, and the used raw materials are easy to purchase, rich in resources, low in price, easy to operate and convenient for large-scale production;

2) the bifunctional electrocatalyst is a non-noble metal sulfide/nitrogen-doped carbon material, has better OER and HER catalytic activities, and has remarkable advantages compared with the unilateral OER or HER activities of non-noble metal/nonmetal catalysts reported in the current research;

3) according to the inventionDual function electrocatalyst and commercial RuO₂Compared with the catalyst, the stability of the catalyst is obviously improved, and the catalyst can keep good catalytic activity in long-term use of an electrolytic water technology.

Description of the drawings:

FIG. 1 shows CoFe-PBA (A) obtained in example 1, CoFe-NFs (B) obtained in example 1, and CoS obtained in example 1₂-FeS₂Scanning Electron microscopy of/NC (C) and CoS obtained in example 1₂-FeS₂(NC) (D) transmission electron microscope image.

FIG. 2 depicts the CoS obtained in example 1₂-FeS₂XRD pattern of/NC catalyst.

FIG. 3 depicts the CoS obtained in example 1₂-FeS₂NC, FeS from comparative example 1₂NC and commercial RuO₂The OER linear sweep voltammograms of the carbon cloths were modified separately.

FIG. 4 shows the CoS obtained in example 1₂-FeS₂Comparative example 1 FeS/NC₂NC NiS from comparative example 2₂-FeS₂MnS-FeS obtained by/NC and comparative example 3₂OER linear sweep voltammogram of/NC modified carbon cloth.

FIG. 5 depicts the CoS obtained in example 1₂-FeS₂The OER constant voltage i-t (left) of the/NC modified carbon cloth and the linear sweep voltammetry curve (right) before and after 1500 cycles of cyclic voltammetry are tested.

FIG. 6 depicts the CoS obtained in example 1₂-FeS₂NC, FeS from comparative example 1₂HER linear sweep voltammograms for the modified carbon cloths of/NC and commercial Pt/C, respectively.

FIG. 7 shows the CoS obtained in example 1₂-FeS₂Comparative example 1 FeS/NC₂NC NiS from comparative example 2₂-FeS₂MnS-FeS obtained by/NC and comparative example 3₂HER linear sweep voltammogram of/NC modified carbon cloth.

FIG. 8 shows the CoS obtained in example 1₂-FeS₂A full-hydrolysis linear scanning voltammogram carried out by the/NC non-noble metal electrocatalyst modified carbon cloth.

FIG. 9 depicts the CoS obtained in example 1₂-FeS₂The carbon cloth modified by NC non-noble metal electrocatalyst is distributed at 1.61VConstant voltage i-t test pattern.

The specific implementation mode is as follows:

for a further understanding of the invention, reference will now be made to the following examples and drawings, which are not intended to limit the invention in any way.

Example 1:

(a) preparation of CoFe-PBA

Weighing 860mg Co (NO)₃)₂·6H₂Dissolving O and 1.32g of sodium citrate in 100mL of deionized water, and marking as a solution A; weighing 658mg of potassium ferricyanide, and dissolving the weighed potassium ferricyanide in another 100mL of deionized water to obtain a solution B; adding the solution B into the solution A under the condition of stirring, stirring for three minutes, standing for 10 hours, centrifuging to collect a sample, washing with deionized water and absolute ethyl alcohol for three times respectively, and drying at 50 ℃ for 12 hours;

(b)CoS₂-FeS₂preparation of/NC

Dispersing 20mg of Co-Fe PBA in 50mL of ethanol, adding the Co-Fe PBA into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifugally collecting a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain a cobalt-iron nano-framework CoFe-NFs;

weighing 20mg of CoFe-NFs, placing the CoFe-NFs in a magnetic boat, placing the magnetic boat at the lower end of a tube furnace, weighing 300mg of sulfur powder, placing the magnetic boat at the upper end of the tube furnace, heating to 400 ℃ at a heating rate of 2 ℃/min, and vulcanizing in a nitrogen atmosphere for 4 hours to obtain the catalyst CoS₂-FeS₂/NC；

Example 2:

(a) preparation of CoFe-PBA

Prepared according to the method and conditions of step (a) in example 1;

(b)CoS₂-FeS₂preparation of/NC

Dispersing 20mg of Co-Fe PBA in 50mL of ethanol, adding the Co-Fe PBA into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifugally collecting a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain a cobalt-iron nano-framework CoFe-NFs;

20mg of the CoFe-NFs was weighed inPlacing a magnetic boat at the lower end of the tube furnace, weighing 300mg of sulfur powder, placing the sulfur powder at the upper end of the tube furnace in the magnetic boat, heating to 200 ℃ at a heating rate of 2 ℃/min, and vulcanizing in a nitrogen atmosphere for 4 hours to obtain the catalyst CoS₂-FeS₂/NC；

Example 3:

(a) preparation of CoFe-PBA

Prepared according to the method and conditions of step (a) in example 1;

(b)CoS₂-FeS₂preparation of/NC

Dispersing 20mg of Co-Fe PBA in 50mL of ethanol, adding the Co-Fe PBA into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifugally collecting a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain a cobalt-iron nano-framework CoFe-NFs;

weighing 20mg of CoFe-NFs, placing the CoFe-NFs in a magnetic boat, placing the magnetic boat at the lower end of a tube furnace, weighing 300mg of sulfur powder, placing the magnetic boat at the upper end of the tube furnace, heating to 300 ℃ at a heating rate of 2 ℃/min, and keeping vulcanization in a nitrogen atmosphere for 4 hours to obtain the catalyst CoS₂-FeS₂/NC；

Example 4:

(a) preparation of CoFe-PBA

Prepared according to the method and conditions of step (a) in example 1;

(b)CoS₂-FeS₂preparation of/NC

Dispersing 20mg of Co-Fe PBA in 50mL of ethanol, adding the Co-Fe PBA into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifugally collecting a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain a cobalt-iron nano-framework CoFe-NFs;

weighing 20mg of CoFe-NFs, placing the CoFe-NFs in a magnetic boat, placing the magnetic boat at the lower end of a tube furnace, weighing 300mg of sulfur powder, placing the magnetic boat at the upper end of the tube furnace, heating to 500 ℃ at a heating rate of 2 ℃/min, and vulcanizing in a nitrogen atmosphere for 4 hours to obtain the catalyst CoS₂-FeS₂/NC；

Example 5:

(a) preparation of CoFe-PBA

Prepared according to the method and conditions of step (a) in example 1;

(b)CoS₂-FeS₂preparation of/NC

Dispersing 20mg of Co-Fe PBA in 50mL of ethanol, adding the Co-Fe PBA into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifugally collecting a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain a cobalt-iron nano-framework CoFe-NFs;

weighing 20mg of CoFe-NFs, placing the CoFe-NFs in a magnetic boat, placing the magnetic boat at the lower end of a tube furnace, weighing 200mg of sulfur powder, placing the magnetic boat at the upper end of the tube furnace, heating to 400 ℃ at a heating rate of 2 ℃/min, and vulcanizing in a nitrogen atmosphere for 4 hours to obtain the catalyst CoS₂-FeS₂/NC；

Example 6:

(a) preparation of CoFe-PBA

Prepared according to the method and conditions of step (a) in example 1;

(b)CoS₂-FeS₂preparation of/NC

Dispersing 20mg of Co-Fe PBA in 50mL of ethanol, adding the Co-Fe PBA into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifugally collecting a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain a cobalt-iron nano-framework CoFe-NFs;

weighing 20mg of CoFe-NFs, placing the CoFe-NFs in a magnetic boat, placing the magnetic boat at the lower end of a tube furnace, weighing 250mg of sulfur powder, placing the magnetic boat at the upper end of the tube furnace, heating to 400 ℃ at a heating rate of 2 ℃/min, and vulcanizing in a nitrogen atmosphere for 4 hours to obtain the catalyst CoS₂-FeS₂/NC；

Comparative example 1:

(a) preparation of FeFe-PB

1.2g Fe (NO) are weighed out₃)₃·6H₂Dissolving O and 1.32g of sodium citrate in 100mL of deionized water, and marking as a solution A; weighing 658mg of potassium ferricyanide, and dissolving the weighed potassium ferricyanide in another 100mL of deionized water to obtain a solution B; adding the solution B into the solution A under the condition of stirring, stirring for three minutes, standing for 10 hours, and then centrifugally collectingThe samples were collected, then washed three times with deionized water and absolute ethanol each, and dried at 50 ℃ for 12 h.

(b)FeS₂Preparation of/NC

Dispersing 20mg of Fe-Fe PB in 50mL of ethanol, adding the ethanol into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifuging to collect a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain an iron-iron nano framework; weighing 20mg of the iron-iron nano frame, placing the iron-iron nano frame in a magnetic boat, placing the iron-iron nano frame at the lower end of a tube furnace, weighing 300mg of sulfur powder, placing the sulfur powder in the magnetic boat, placing the sulfur powder at the upper end of the tube furnace, heating to 400 ℃ at a heating rate of 2 ℃/min, and keeping vulcanization for 4 hours in a nitrogen atmosphere to obtain the catalyst FeS₂/NC；

Comparative example 2:

(a) preparation of NiFe-PBA

Weighing 870mg Ni (NO)₃)₂·6H₂Dissolving O and 1.32g of sodium citrate in 100mL of deionized water, and marking as a solution A; weighing 658mg of potassium ferricyanide, and dissolving the weighed potassium ferricyanide in another 100mL of deionized water to obtain a solution B; adding the solution B into the solution A under the condition of stirring, stirring for three minutes, standing for 10 hours, centrifuging to collect a sample, washing with deionized water and absolute ethyl alcohol for three times respectively, and drying at 50 ℃ for 12 hours;

(b)NiS₂-FeS₂preparation of/NC

Dispersing 20mg of NiFe PBA in 50mL of ethanol, adding the mixture into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifugally collecting a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain the nickel-iron nano-frame NiFe-NFs;

weighing 20mg of NiFe-NFs, placing the NiFe-NFs in a magnetic boat, placing the magnetic boat at the lower end of a tube furnace, weighing 300mg of sulfur powder, placing the magnetic boat at the upper end of the tube furnace, heating to 400 ℃ at a heating rate of 2 ℃/min, and vulcanizing in a nitrogen atmosphere for 4 hours to obtain the catalyst NiS₂-FeS₂/NC；

Comparative example 3:

(a) preparation of MnFe-PBA

Weighing 500mg MnSO₄·H₂O and 1.32g lemonDissolving sodium citrate in 100mL of deionized water, and marking as a solution A; weighing 658mg of potassium ferricyanide, and dissolving the weighed potassium ferricyanide in another 100mL of deionized water to obtain a solution B; adding the solution B into the solution A under the condition of stirring, stirring for three minutes, standing for 10 hours, centrifuging to collect a sample, washing with deionized water and absolute ethyl alcohol for three times respectively, and drying at 50 ℃ for 12 hours;

(b)MnS-FeS₂preparation of/NC

Dispersing 20mg of MnFe PBA in 50mL of ethanol, adding the ethanol into 50mL of 25% ammonia water solution, stirring and reacting for 10min, centrifuging to collect a sample, washing the sample with deionized water until the solution is nearly neutral, and drying the sample at 60 ℃ for 24h to obtain a nickel-iron nano-framework MnFe-NFs;

weighing 20mg of NiFe-NFs, placing the NiFe-NFs in a magnetic boat, placing the NiFe-NFs in the lower end of a tube furnace, weighing 300mg of sulfur powder, placing the sulfur powder in the magnetic boat, placing the sulfur powder in the upper end of the tube furnace, heating to 400 ℃ at a heating rate of 2 ℃/min, and vulcanizing for 4 hours in a nitrogen atmosphere to obtain the catalyst MnS-FeS₂/NC；

FIG. 1 shows CoFe-PBA, CoFe-NFs and CoS obtained in example 1(A), example 1(B) and example 1(C), respectively₂-FeS₂Scanning Electron microscopy of/NC and CoS obtained in example 1₂-FeS₂(NC) (D) transmission electron microscope image. As can be seen from FIG. A, the crystal grains of CoFe-PBA appear as regular cubes, and CoFe-PBA has a good crystal form. As can be seen from FIG. B, the edges of the cubes of the ammonia etched CoFe-PBA were destroyed, but the cube skeleton was substantially maintained. Panel C and D show that the material retains a cubic structure after gas phase vulcanization, where panel D shows CoS₂-FeS₂Uniformly distributed on the surface of the cube, presenting a hollow cage-like structure, which may be the result of gradual migration of internal components to the external surface during high temperature vulcanization.

FIG. 2 depicts the CoS obtained in example 1₂-FeS₂XRD pattern of/NC catalyst. By comparison with a standard card, the main component of the sample after vulcanization was found to be CoS₂And FeS₂Corresponding to standard cards JCPDS41-1471 and JCPDS 42-1340 respectively. Indicating that CoFe-PBA is converted into nitrogen-doped carbon-loaded transition metal for vulcanization after ammonia etching and vulcanizationSubstance CoS₂-FeS₂The heterostructure is beneficial to regulation and control of an electronic structure, and the electrocatalytic performance of the catalyst is improved.

The electrocatalysis performance test adopts a saturated Ag/AgCl electrode as a reference electrode, a Pt electrode as a counter electrode, the sweep rate is 5mV/s, the electrolyte is 1M KOH, and the electrolyte needs to be subjected to N before the OER catalysis performance test₂And (5) saturation treatment.

FIG. 3 depicts the CoS obtained in example 1₂-FeS₂NC, FeS from comparative example 1₂NC and commercial RuO₂The OER linear sweep voltammograms of the carbon cloths were modified separately. As can be seen from the figure, the current density reached 10mA/cm²Of CoS₂-FeS₂The presence of the/NC heterostructure has the lowest overpotential, indicating the transition metal sulfide CoS₂-FeS₂The existence of the catalyst plays a role in synergistically promoting the OER performance of the catalyst, further increases the active sites of the carbon material, improves the surface property of the catalyst, and ensures that CoS₂-FeS₂The electrochemical activity of the/NC is better than that of single-phase metal sulfide FeS₂/NC。

FIG. 4 shows the CoS obtained in example 1₂-FeS₂Comparative example 1 FeS/NC₂NC NiS from comparative example 2₂-FeS₂MnS-FeS obtained by/NC and comparative example 3₂OER linear sweep voltammogram of/NC modified carbon cloth. Considering transition metal cobalt sulfide and FeS₂When the catalyst is matched as an OER catalyst, the performance is greatly improved, and other transition metal sulfides and FeS are examined₂Catalytic performance in the formation of heterostructures, respectively synthesizing NiS₂-FeS₂(iii) NC and MnS-FeS₂(ii)/NC sulfides of two transition metals Mn and Ni, as shown in FIG. 4, comparing four catalysts NiS₂-FeS₂/NC，MnS-FeS₂/NC，CoS₂-FeS₂/NC，FeS₂OER performance of/NC in 1M KOH solution environment, it can be seen that sulfide of transition metal Co still shows the best catalytic activity, and for NiS₂-FeS₂NC, when catalyzing OER, 10mA/cm is achieved²Current density of (1.47V vs. RHE, MnS-FeS)₂instead,/NC shows worse catalytic performance.

FIG. 5 depicts the CoS obtained in example 1₂-FeS₂OER stability test conducted on/NC modified carbon cloth. Catalyst CoS supported on carbon cloth₂-FeS₂and/NC, the catalytic performance is not obviously attenuated after a stability test for 25 h. After 1500 cycles of CV testing, the LSV curves almost coincide, indicating that the catalyst has excellent long-term stability.

FIG. 6 depicts the CoS obtained in example 1₂-FeS₂NC, FeS from comparative example 1₂HER linear sweep voltammograms for the modified carbon cloths of/NC and commercial Pt/C, respectively. It can be seen that the current density reached 10mA/cm²Of CoS₂-FeS₂the/NC heterostructure has the lowest overpotential, indicating the transition metal sulfide CoS₂-FeS₂The existence of the catalyst plays a role in synergistically promoting the OER performance of the catalyst, further increases the active sites of the carbon material, improves the surface property of the catalyst, and ensures that CoS₂-FeS₂The electrochemical activity of the/NC is better than that of single-phase FeS₂/NC。

FIG. 7 shows the CoS obtained in example 1₂-FeS₂Comparative example 1 FeS/NC₂NC NiS from comparative example 2₂-FeS₂MnS-FeS obtained by/NC and comparative example 3₂HER linear sweep voltammogram of/NC modified carbon cloth. Further examination of NiS₂-FeS₂/NC，MnS-FeS₂Catalytic activity of two materials,/NC on HER, as shown in FIG. 7, material NiS₂-FeS₂The NC reaches 10mA/cm²The current density of (A) is 327mV, obviously greater than CoS₂-FeS₂the/NC reaches the overpotential generated in the same case. MnS-FeS₂The NC reaches 10mA/cm²The overpotential generated at the current density of (1) is 437mV compared with sulfide FeS of single-phase metallic Fe₂Good performance of/NC.

FIG. 8 shows the CoS obtained in example 1₂-FeS₂The graph shows that when the current density reaches 10mA/cm, the total water splitting linear scanning voltammetry curve of the carbon cloth modified by the NC non-noble metal electrocatalyst²When the target catalystThe required potential of which is significantly less than that of the noble metal RuO₂Indicating CoS distributed at the edges of the cube₂-FeS₂Is beneficial to the direct contact of reactants or reaction intermediates and active sites, thereby improving the electrocatalytic performance.

FIG. 9 depicts the CoS obtained in example 1₂-FeS₂A constant voltage i-t test chart when the/NC non-noble metal electrocatalyst modified carbon cloth is arranged at 1.61V. As can be seen from the figure, in the 16h test, CoS₂-FeS₂The performance of the/NC is only attenuated by 5.8%, the good long-term stability of the electrolyzed water is shown, the method has important significance in the application of new energy in the future, and has potential application value in the field of electrode materials of the electrolyzed water technology.

Claims (2)

1. The Prussian blue analogue derived metal sulfide/nitrogen-doped carbon electrocatalyst is characterized in that the catalyst takes a cobalt-iron Prussian blue analogue as a template, and CoS is obtained by ammonia etching and gas phase sulfidation₂-FeS₂A nitrogen-doped carbon catalyst; wherein the cobalt iron Prussian blue analogue is marked as CoFe-PBA, CoS₂-FeS₂N-doped carbon catalyst is described as CoS₂-FeS₂/NC；

The preparation method of the metal sulfide/nitrogen-doped carbon electrocatalyst derived based on the blue analogue is characterized by comprising the following specific steps of:

(a) preparation of CoFe-PBA

Weighing 870mg Co (NO)₃)₂·6H₂Dissolving O and 1.32g of sodium citrate in 100mL of deionized water, and marking as a solution A; weighing 658mg of potassium ferricyanide and dissolving the potassium ferricyanide into another 100mL of deionized water, and marking as a solution B; adding the solution B into the solution A under the condition of stirring, stirring for three minutes, standing for 10 hours, centrifuging to collect a sample, washing with ionized water and absolute ethyl alcohol for three times respectively, and drying at 50 ℃ for 12 hours;

(b)CoS₂-FeS₂preparation of/NC

Dispersing 20mg Co-Fe PBA in 50mL ethanol, adding into 50mL 25% ammonia water solution, stirring for reaction for 10min, centrifuging to collect sample, and removing ionsWashing with water until the solution is nearly neutral, and drying at 60 ℃ for 24h to obtain a cobalt-iron nano-framework marked as CoFe-NFs; weighing 20mg of CoFe-NFs in a magnetic boat, placing the magnetic boat in the lower end of a tube furnace, weighing 200-400 mg of sulfur powder in the magnetic boat, placing the magnetic boat in the upper end of the tube furnace, heating to 200-500 ℃ at the speed of 2 ℃/min, and vulcanizing in a nitrogen atmosphere for 1-5 hours to obtain the catalyst CoS₂-FeS₂/NC；

The metal sulfide/nitrogen-doped carbon electrocatalyst is of a hollow nano cubic cage structure, elements are uniformly distributed on the edges of a cube, and the average particle size of nano cubic cage units of the catalyst is 100-200 nm; metal sulfide CoS₂-FeS₂The average grain diameter of the nano-particles is 5-30nm, and the nano-particles are uniformly embedded on the nitrogen-doped carbon nano-chip.

2. The prussian blue analog-derived metal sulfide/nitrogen-doped carbon electrocatalyst according to claim 1, characterized in that the catalyst is used for cathodic hydrogen evolution reaction and anodic oxygen evolution reaction of electrolyzed water.

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