Ionic Liquid-Assisted Synthesis of Mesoporous Carbons with Surface-Enriched Nitrogen for the Hydrogen Evolution Reaction

Heteroatom-doped carbon materials are promising metal-free catalysts for the hydrogen evolution reaction (HER) at low voltage with high durability. However, many of the active sites introduced by heteroatom doping are hardly accessible within the bulk carbon structure and consequently contribute little to the catalytic activity. Here we report a facile ionic liquid-assisted method for synthesizing mesoporous nitrogen-doped carbons, enabling enrichment of nitrogen atoms at the pore surface, demonstrated by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption of carbon dioxide (CO 2 -TPD). The resulting metal-free nitrogen-doped mesoporous carbons exhibit a remarkable electrocatalytic activity in HER. The accessible and efficient utilization of nitrogen atoms is responsible for the superior HER catalytic activity.