| The non-renewable traditional fossil fuels are increasingly depleted,causing two major world problems,the energy crisis and environmental pollution.The development of clean and renewable hydrogen energy is one of the effective ways to solve the problem.Water splitting technology is considered to be a feasible and promising route for hydrogen production.Although Pt-based precious metals are currently considered as the best catalysts for electrocatalytic hydrogen evolution,their large-scale applications are constrained by the disadvantages of high cost and low reserves.Therefore,it is of great research significance to develop a high-efficiency,stable,earth-rich non-precious metal hydrogen evolution electrocatalyst that can replace Pt-based materials.In recent years,transition metal sulfide has become a research hotspot because of its highly efficient electrocatalytic hydrogen evolution activity,and it is considered to be a promising alternative electrocatalyst material for Pt.The reaction of water splitting mainly occurs on the surface of the catalyst,therefore,the performance of the electrocatalyst is closely related to the morphology and microstructure.In addition,most of the traditional materials are in the form of powder.The required polymer binder seriously affects the contact between the catalyst surface and the electrolyte,blocking the reactive sites in a certain extent and making the catalytic activity of the material decrease.Herein,three types of self-supported electrocatalysts materials MoS2/MF,VS2/MoS2/MF and Mo-Cu2S/CF were designed and synthesized by regulating the surface structure of the electrocatalyst and improving the hydrogen evolution activity of the catalyst.The main conclusions of this thesis include the following three parts:(1)The molybdenum disulfide nanosheet array(MoS2/MF)grown on a molybdenum foil was synthesized by using ammonium molybdate tetrahydrate and thioacetamide as starting materials and using the etching effect of ammonia water.The synthesis mechanism of MoS2/MF,the effects of hydrothermal temperature and amount of ammonia added on the phase,morphology,and electrocatalytic performance of the sample were explored.The effect of IT-MoS2 addition on the hydrogen evolution performance of MoS2/MF was clarified.The prepared MoS2/MF shows high catalytic hydrogen evolution performance in acidic solution(0.5 M H2SO4)and it can work stably at least 65h.(2)Using sodium metavanadate,ammonium molybdate tetrahydrate,and thioacetamide as raw materials,a few layers of molybdenum disulfide nanobelts embedded in vanadium disulfide microflower heterostructure were synthesized on the molybdenum foil by one-step hydrothermal method(VS2/MoS2/MF).We studied the regulation effect of the amount of Mo source on the morphology of VS2/MoS2/MF,explored the regulation of MoS2 nanoribbons on the surface chemical state and hydrogen evolution active sites of VS2 microflower,The prepared VS2/MoS2/MF exhibits high catalytic hydrogen evolution performance under large current density.In an acidic environment,only a small overpotential(282 mV and 336 mV)are required for driving current densities of 500 mA/cm2 and 1000 mA/cm2,while VS2/MoS2/MF can maintain work stably at least 24 h.(3)Using sodium molybdate dihydrate and thioacetamide as starting materials,copper foam as copper source and substrate.The Mo-Cu2S nanosheets(Mo-Cu2S/CF)were obtained through hydrothermal reaction.The influence of hydrothermal reaction time on sample synthesis was explored.The regulation effect of Mo doping on the electronic structure of Mo-Cu2S/CF and the enhancement of electrocatalytic hydrogen evolution performance were revealed. |
PDF Full Text Request