Highly active nonprecious metal hydrogen evolution electrocatalyst: ultrafine molybdenum carbide nanoparticles embedded into a 3D nitrogen-implanted carbon matrix

摘要

A three-dimensional, porous catalytic framework makes it easier to flow water past active sites that turn this molecule into hydrogen. The hunt for cheaper alternatives to platinum catalysts for water splitting led Jinhua Ye from Tianjin University in China and co-workers to investigate molybdenum carbide (Mo2C). These catalysts show significant hydrogen evolution when confined to nanoscale shapes. The researchers enhanced this behaviour by replacing imidazole-zinc units in a zeolite-type metal organic framework with molybdenum. Heating at high temperature turned the sieve-like template into a new composite containing ultrafine Mo2C nanoparticles and a three-dimensional matrix of graphitic carbon implanted with nitrogen atoms. The physical structure of this material improves mass transport of reagents to and from catalytic surface sites, while favorable interactions between Mo2C and the carbon matrix lower energy barriers needed to slice water apart.