Research On Preparation And Performances Of Non-noble Metal-based Chalcogenides For Electrochemical Hydrogen Evolution Reaction

With the rapid development of society,the problem of energy crisis and environmental pollution has become an obstacle to the sustainable development of contemporary society.With the characteristics of cleanliness,high energy density and regeneration,hydrogen energy is considered as a promising alternative to relieve the dependence on fossil fuels.The technology of hydrogen production by electrolytic water is deemed as an effective and environmentally friendly method to convert electric energy into chemical energy because of its simple operation,easy scale and high purity of hydroge n.Currently,the exploring of non-noble metal catalyst with the merits of high efficiency,stability,low price and low overpotential is the key to promote the development of hydrogen production technology through water splitting.In this thesis,nanotremella-like Bi₂S₃/MoS₂,nanostalactite-like SnS₂/CoS_1.097/GO,nanotremella-like NiSe₂ modified with CeO₂ and rock-like MoS₂ modified with Sm₂O₃have been prepared with a hydrothermal or solvothermal method.The morphorlogy,composition,structure and the hydrogen evolution performance in alkaline condition have been investigated with a series of physical and electrochemical methods.The main contents are as follows:?1?In the first step,Bi₂S₃ nanorods have been prepared using Bi?NO₃?₃·5H₂O and thioacetamide as raw materials.In the second step,a series of nanotremella-like catalysts with different mass ratios of Bi₂S₃ to MoS₂ were prepared by adjusting the contents of as-prepared Bi₂S₃,Na₂MoO₄·2H₂O and thioacetamide.The results indicate that the catalytic performance of as-prepared Bi₂S₃/MoS₂ is better than those of pure Bi₂S₃ and MoS₂.When the theoretical mass ratio of Bi₂S₃ to MoS₂ is 5:5,as-prepared BMS-5catalyst has the smallest overpotential of 124 mV at current density of 10 mA cm^-2.At overpotential of 400 mV,the current density of BMS-5 reaches up to 105 mA cm^-2,while those of Bi₂S₃ and MoS₂ are 13 and 34 mA cm^-2,respectively.Besides,the polarization curves of BMS-5 catalyst almost coincide before and after stability test for 24 h,showing satisfactory stability.?2?Based on the good electrical conductivity and abundant functional groups on the surface of graphene oxide,a series of nanostalactite-like SnS₂/CoS_1.097/GO composite catalysts with different molar ratios of Sn⁴⁺to Co²⁺have been prepared with a solvothermal method.The results show that when the molar ratio of Sn⁴⁺to Co²⁺is 2:8,as-prepared SCS-2/GO catalyst shows good catalytic activity.The SCS-2/GO catalyst shows overpotential of 166mV at current density of 10 mA cm^-2,while those of SnS₂,CoS_1.097,SCS-0.5/GO,SCS-1/GO and SCS-4/GO are 309,277,236,229 and 263 mV,respectively.At overpotential of 400 mV,the current density of SCS-2/GO catalyst is up to 60 mA cm^-2,while those of SnS₂,CoS_1.097,SCS-0.5/GO,SCS-1/GO and SCS-4/GO are 21,29,46,51and 33 mA cm^-2,respectively.In addition,SCS-2/GO shows excellent stability during the durability test for 24 h.?3?Based on the unique 4f and 5d electronic configuration of Ce and the intrinsically catalytic activity of NiSe₂,a series of nanocoral-like NiSe₂ catalysts modified with different molar contents of CeO₂ with a hydrothermal method.The results indicate that when the theoretical molar percentage of CeO₂ is 5%,as-prepared CNS-2 catalyst exhibits the smallest overpotential.To obtain the current density of 10 mA cm^-2,the overpotential is only 130 mV for CNS-2,while those for NiSe₂,CSN-1 and CNS-3 are 230,165 and 143mV,respectively.At higher current density of 50 mA cm^-2,the overpotential of CNS-2 is only 242 mV,while those of NiSe₂,CSN-1 and CNS-3 are up to 427,330 and 278 mV,respectively.Moreover,the polarization curves of the CNS-2 catalyst almost coincide before and after stability test for 24 h,indicating good electrochemical stability.?4?Based on the special peripheral electronic configuration of Sm,a series of rock-like MoS₂ catalysts modified with Sm₂O₃ have been prepared with a solvothermal method.When the molar percentage of Sm₂O₃ is 3%in raw materials,as-prepared MSS-2 catalyst needs the lowest overpotential of 137 mV to acquire the current density of 10 mA cm^-2,while those of MoS₂,MSS-1 and MSS-3 are 252,213 and 210 mV,respectively.MSS-2needs overpotential of 252 mV to drive the current density of 40 mA cm^-2,while those of MoS₂,MSS-1 and MSS-3 need 418,363 and 318 mV,respectively.Besides,the polarization curves of MSS-2 catalyst almost coincide before and after stability test for 24h,reflecting a good electrochemical stability.In this thesis,a series of non-noble metal-based chalcogenides and their composites have been prepared with simple methods.The electrochemical test results show that nanotremella-like Bi₂S₃/MoS₂,nanostalactite-like SnS₂/CoS_1.097/GO,nanocoral-like NiSe₂modified with CeO₂ and rock-like MoS₂ modified with Sm₂O₃ exhibit favorable electrocatalytic performance in alkaline electrolyte,indicating that as-prepared non-noble metal-based chalcogenides and their composites can be promising cathode materials for hydrogen evolution reaction.