| Along with the continuous development of human society,the demand for renewable energy is increasing.Electrochemical energy conversion and storage technologies（electrolytic water,fuel cells,etc.）have become a research hotspot because of their advantages of high energy conversion efficiency and environmental friendliness.Electrocatalytic hydrolysis is a safe and efficient way to prepare hydrogen energy,including hydrogen evolution reaction（HER）at the cathode and oxygen evolution reaction（OER）at the anode.Hydrogen is considered to be one of the most promising clean energy sources to alleviate the energy crisis and environmental pollution.At present,the most efficient HER and OER catalysts are still platinum-based and ruthenium-based precious metal systems,but their reserves are limited,and it is important to develop cheap electrode materials with abundant reserves.Metal sulfides with spinel-structure have received wide attention for their excellent catalytic activity and low cost,among which bimetallic spinel structured compounds have received widespread attention due to the synergistic effect between metal atoms that can effectively enhance catalytic activity,and it is a meaningful research topic to further improve the electrical conductivity of spinel structured metal sulfides and increase the specific surface area to increase the electrochemical active sites.Based on the above research background,in this paper,MCo2S4（M=Ni,Cu）spinel-type metal sulfides were prepared using ZIF-67 as a sacrificial template.The electrocatalytic performance was improved by the strategy of metal ion doping and compounding with other metal sulfides.The main research results are summarized as follows:（1）The Fe doped Ni Co2S4catalysts were prepared by the solvothermal method using the metal-organic backbone ZIF-67 as a template,and the HER properties of the materials were tested in alkaline electrolyte.The overpotentials before and after doping were 252m V@10 m A cm-2and 181 m V@10 m A cm-2,respectively,and the Tafel slopes were 149m V dec-1and 125 m V dec-1,respectively.The mesoporous structure was preserved by using the ZIF-67 as a template,the conductivity of the material was improved by Fe doping which decreased the reaction internal resistance,increased the electrochemical double-layer capacitance,and enhanced charge transport,thus enhanced the HER catalytic performance.（2）CuCo2S4was synthesized using ZIF-67 as a template and CuCo2S4@Mo S2catalysts（C@M-0.5,C@M-1,C@M-2）were obtained by compounding different contents of Mo S2on its surface.The composite catalysts not only retained the advantages of the ZIF-67 template,but also exploited the synergistic coupling effect between CuCo2S4and Mo S2,thus exhibiting better HER catalytic activity than Mo S2and CuCo2S4.Among them,C@M-1 exhibited the best HER electrocatalytic performance with an overpotential of 143 m V@10m A cm-2and a Tafel slope of 45.2 m V dec-1in 0.5 M acidic electrolyte,along with excellent cycling stability.（3）CuCo2S4@Co S2bifunctional catalysts were prepared by synthesizing CuCo2S4using ZIF-67 as a template and modifying it with Co S2.The three-dimensional interconnected nanosheet structure of CuCo2S4@Co S2can provide abundant electrocatalytic active sites and fast diffusion pathways for reactants and intermediates.CuCo2S4@Co S2exhibited good HER and OER activities in 1 M alkaline electrolyte with overpotentials of 153m V@10 m A cm-2and 261 m V@10 m A cm-2,respectively.By using CuCo2S4@Co S2as a catalyst in total decomposition of water,a current density of 10 m A cm-2could be achieved with only 1.61 V and the composite electrocatalyst also has a good long-term stability. |
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