Fabrication Of Transition Metal Sulfide (Selenide )/Functionalized Carbon Composite Materials As Efficient Electrocatalysts For Hydrogen Evolution Reaction

Hydrogen is considered as one of the cleanest energy sources which are most promising to replace traditional fossil fuels.Among various hydrogen evolution techniques,hydrogen evolution reaction?HER?by electrocatalytic reduction of water is considered the cleanest and recyclable technique.High efficient electrocatalysts are needed to improve the efficiency and kinetic rate of HER.Up to now,noble metals,especially Pt-based catalysts were proved to be the most effective catalysts for HER.However,limited reserves and high prices severely prevent large scale application of Pt-based catalysts.Thus,cost-effective catalysts with high catalytic activities are urgently desirable.In this respect,graphitic carbon,especially N-doped graphitic carbons supported active catalysts,such as transition metal sulfides,become more and more attractive due to their high catalytic performances and stabilities.This thesis aims at fabrication of composite catalysts by supporting MoS₂ and CoSe₂ on heteroatom,especially nitrogen doped functionalized carbon materials,and following studies were carried out.?1?Nitrogen-doped carbon materials?NCNH?were prepared by pyrolysis of the precursor ZIF-8,using ZnCl₂ as the activator.Composite catalysts of Mo S₂/NCNH and Co Se₂/NCNH were fabricated by using NCNH as the support.The pyrolysis temperature of precursor and the loading of the catalysts were investigated.The results have shown that the catalysts Mo S₂/NCNH-800-50 and CoSe₂/NCNH-800-170exhibit the highest catalytic activity in 0.5 mol/L H₂SO₄.The initial reduction potential of-221 m V and-178 mV?vs RHE?,and Tafel slope of 50 mV/dec and 85m V/dec were obtained,respectively.The two catalysts also have shown good stability in the recycling tests.?2?Graphene-likecarbonmaterial?MCS-1?werepreparedfrom1,2,4,5-Benzenetetracarboxylic anhydride and benzidine.Composite catalysts of Mo S₂/MCS-1 and CoSe₂/MCS-1 were fabricated by using MCS-1 as the support.The pyrolysis temperature of precursor and the loading of the catalysts were investigated.The results have shown that the catalysts Mo S₂/MCS-1-800-80 and CoSe₂/MCS-1-800-100 exhibit the highest catalytic activity in 0.5 mol/L H₂SO₄.The initial reduction potential of-207 mV and-189 mV?vs RHE?,and Tafel slope of 50m V/dec and 72 m V/dec were obtained,respectively.The two catalysts also showed good stability in the recycling tests.?3?Sulfur-doped graphitic carbon materials?SDGC?were prepared and composite catalysts of Mo S₂/SDGC and Co Se₂/SDGC were fabricated by using SDGC as the support.The pyrolysis temperature of precursor and the loading of the catalysts were investigated.The results have shown that the catalysts Mo S₂/SDGC^-4-800-50 and Co Se₂/SDGC^-2-800-60 exhibit the highest catalytic activity in 0.5 mol/L H₂SO₄.The initial reduction potential of-193 mV and-178 m V?vs RHE?,and Tafel slope of 60 m V/dec and 73 mV/dec were obtained,respectively.The two catalysts also have shown good stability in the recycling tests.