Structure Control And Performance Study Of MXene-based Electrocatalysts

Hydrogen is considered to be a promising alternative to traditional energy sources.At present,the hydrogen production methods include chlor-alkali production,water electrolysis,industrial chemicals and fossil fuels splitting.Water electrolysis is an effective method to prepare hydrogen with high purity.However,the decomposition of water is a relatively difficult process,which requires 237 k J of energy per mole of water to overcome the energy barriers of HER（Hydrogen Evolution Reaction）and OER（Oxygen Evolution Reaction）.In addition,extra electric energy is required to overcome the resistance and realize ions transfer.High overpotential brings energy consumption,thus development of efficient catalysts to diminish overpotential is vital.At present,Pt predominated in the catalyst is normal used for HER,while Ru O₂ and Ir O₂for OER,the high price and scarce reserves limit the large-scale use.Therefore,it is urgent to develop catalysts with low cost,high activity and high stability.Compared with controling catalytic particles,designing support structure is a new way to enhance its performance.MXene based three-dimensional porous structure enable catalysts expose abundant catalytic active sites,which can improve the catalytic performance material transport capacity.Based on the morphology and structure regulation of supports and active particles,this paper aims to design and synthesize efficient and stable catalysts for water electrolysis.The content of this paper mainly includes three parts:（1）Pt/Ti₃C₂T_x-r GO_3D catalyst was prepared through Pt nanoparticles loaded on three-dimensional porous structures support.Three dimensional porous support was prepared by hydrothermal reaction of Ti₃C₂T_x and GO.Pt/Ti₃C₂T_x-r GO_3Dshowed high HER activity thatη₁₀(overpotential at a current density of 10 m A cm^-2)was 41 m V and Tafel slope was 28 m V dec^-1.The overpotential of Pt/Ti₃C₂T_x-r GO_3D catalyst only decreased by 30 m V after the stability test lasting 30000 s.（2）Co P/Mo₂Ti C₂T_x-r GO_3D catalyst was prepared by the growth of cobalt phosphide on three-dimensional porous support.Co（NO₃）₂·6H₂O and Na H₂PO₂ were used as CO and P sources respectively to prepare catalyst by hydrothermal and low temperature phosphating.The catalyst showed excellent performance in HER and OER.Theη₁₀ of HER and OER were 113 m V and 297 m V,respectively.In the stability test,the potential increased by 24 m V after 10000 s for HER and 67 m V after 30000 s for OER.（3）Fe S₂/Mo₂Ti C₂T_x-r GO_3D non noble metal catalyst was prepared by growing iron sulfide on Mo₂Ti C₂T_x-r GO_3D composite support.Fe（NO₃）₃·9H₂O and TAA were used as Fe and S sources respectively,and the catalyst were crystallized by hydrothermal and low temperature annealing.In HER reaction,η₁₀ is 196 m V and Tafel slope is 70 m V dec^-1.