Synthesis Of Carbon-based Molybdenum Carbide Composite Nanomaterials For Electrocatalytic Hydrogen Evolution

Due to its similar energy band structure to Pt,Molybdenum carbide?Mo₂C? is considered to be a highly potential non-precious metal-based electrocatalyst for hydrogen evolution.Although various structural carbon materials have been designed as frameworks for anchoring molybdenum carbide to effectively improve the catalytic performance of hydrogen evolution reaction?HER?,simply and uniformly hybridizing the suitable molybdenum and carbon source to fabricate well-defined heteroatoms doped nanostructured carbon/molybdenum carbide with high HER activity is still great challenge.Aiming to expose more catalytic active sites,accelerate the mass transfer process and optimize the electronic structure,we designed and synthesized biomass-derived carbon microspheres and carbon nanoflower-based molybdenum carbide composites as the electrocatalysts for enhanced HER performance.The relationship between material structure and performance were explored in detail.The specific research content is listed as follows:?1?N/P-co-doped molybdenum carbide/porous carbon hybrid rough microspheres were prepared using red jujube as the carbon source and phosphomolybdic acid as the molybdenum source by simple hydrothermal and followed by carbonization techniques.Benefiting from carbon framework derived from red jujube inhibiting the aggregation of Mo₂C nanoparticles,N/P co-doping changing the electro-structure of the adjacent Mo and C atoms,and rough micro-spherical structure exposing more active sites,the resulting material exhibits high electrocatalytic performance with a low overpotential of 103 and 80 m V at current densities of 10 m A cm^-2,a small Tafel slope of 57 and 46 m V dec^-1,respectively,in acidic and alkaline electrolyte,and excellent stability.The convenient resource,facile preparation and high performance make this material showing great potential in cost effective hydrogen production.?2?Ultrafine N-doped Mo₂C nanoparticles anchored into N-doped carbon nanoflower have been fabaricated using a cationic surfactant as a linker to bridge carbon and molybdenum sources.Such designed structure offers the following advantages for HER:1)ultrafine Mo₂C nanocrystals dispersed into the carbon nanoflower affords more accessible active centers for HER;2)flower-like structure with meso-porous channels facilitates fast diffusion of the electrolyte;3)nitrogen doping in Mo₂C crystalline and carbon framework lowers desorption energy of Mo-H bond for easy evolution of hydrogen gas.As a result,as-prepared electrocatalyst displays excellent HER activity with an extremely low overpotential?60 and 48 m V?to achieve current density of 10 m A cm^-2,a very small Tafel slope(31 and 34 m V dec^-1) and excellent durability in both acidic and alkaline media,which is highly comparable to the commercial Pt/C catalyst.This indicatesthat the electrocatalyst is a great potential candidate for HER.