Preparation Of Metal Carbon Composites And Electrocatalytic Performance For Hydrogen Evolution

The development of high-performanced and,stable catalysts for electrocatalytical water splitting is the key to achieving large-scale electrolyzed water hydrogen production.Theoretical and experimental research shows that transition metal carbon composites are excellent catalysts for replacing noble metal-based catalysts such as Pt due to their rich earth reserves and excellent electrochemical performance.It has been proved that HER performance can be effectively improved by constructing heterogeneous nanocomposites with different morphologies by atomic doping and enhancing the interaction between the active components of the composite.This article conducts research on the above two aspects.Study on the composite action of Mo₂C and Ni based on new biomass carbon materials to construct fibrous HER catalyst;Using the interface adjustment method,Mo₂C/Ni nanoparticles with in situ growth phase interface were prepared as excellent water catalysts for water splitting.The dissertation mainly consists of the following aspects:1.Carbon microfibers modified with Mo₂C and metallic Ni（Mo₂C-Ni-CMF0.2）wassuccessfully synthesized by one-step strategy and demonstrated that it is efficientand stable low-cost electrocatalyst for hydrogen evolution reaction（HER）in acidicconditions.The as-obtained Mo₂C-Ni-CMF0.2 shows excellent HER activity witha low overpotential（131 mV）to reach current density of 10 mA cm^?2,a small Tafelplot(34.1 mV dec^?1)and remarkable stability.The carbonized cotton fibers has apore structure and a large specific surface area,which is beneficial for improvingelectrocatalytic activity.Moreover,cotton fibers also provide a carbon source forthe formation of Mo₂C during carbonization.The catalyst owes better activity to theelectrion transmission facilitated by the synergy between Mo₂C and Ni,and theadsorption of H⁺based on pore structure.2.Herein,strongly coupled Mo₂C and Ni nanoparticles with in-situ formed interfacesencapsulated by porous carbon nanofibers（Ni-Mo₂C-CNF）have been rationallyfabricated via pyrolyzing electrospinning polyvinyl alcohol fibers containinghydrothermally obtained NiMoO₄ under Ar atmosphere and applied as high-performance and stable electrocatalyst for HER in alkaline electrolytes.Poweredby NiMoO₄ as homologous bimetallic precursor,the Ni-Mo₂C-CNF possessesnumerous in-situ formed Ni-Mo₂C interfaces,which facilitates the synergistic effectbetween Ni and Mo₂C,improving the conductivity and thus boosting theelectrocatalytic performance towards HER.In the meantime,the porous carbon nanofibers with well encapsulated Ni-Mo₂C active components stacks,constituting conductive network,which promotes the mass transport,electron transfer,active sites exposure and electrocatalytic stability.As a result,the Ni-Mo2C-CNF features prominently in HER,as it demands a low overpotential of 196 mV but is able to stably yield the current density of 10 mA cm^-2 with a small Tafel plot of 54.7 mV dec^-1 The method demonstrated in our work to synthesize bimetallic heterostructured materials will offer valuable inspiration to construct promising non-precious electrocatalysts for diverse vital renewable energy applications.