Developing affordable and efficient electrocatalysts as precious metal alternatives toward the hydrogen evolution reaction (HER) is crucially essential for the substantial progress of sustainable H2 energy-related technologies. The dual manipulation of coordination chemistry and geometric configuration for single-atom catalysts (SACs) has emerged as a powerful strategy to surmount the thermodynamic and kinetic dilemmas for high-efficiency electrocatalysis. We herein rationally designed N-doped multichannel carbon nanofibers supporting atomically dispersed Mo sites coordinated with C, N, and O triple components (labeled as Mo@NMCNFs hereafter) as a superior HER electrocatalyst. Systematic characterizations revealed that the local coordination microenvironment of Mo is determined to be a Mo-O1N1C2 moiety, which was theoretically probed to be the energetically favorable configuration for H intermediate adsorption by density functional theory calculations. Structurally, the multichannel porous carbon nanofibers with open ends could effectively enlarge the exposure of active sites, facilitate mass diffusion/charge transfer, and accelerate H2 release, leading to promoted reaction kinetics. Consequently, the optimized Mo@NMCNFs exhibited superior Pt-like HER performance in 0.5 M H2SO4 electrolyte with an overpotential of 66 mV at 10 mA cm-2, a Tafel slope of 48.9 mV dec-1, and excellent stability, outperforming a vast majority of the previously reported nonprecious HER electrocatalysts. The concept of both geometric and electronic engineering of SACs in this work may provide guidance for the design of high-efficiency molecule-like heterogeneous catalysts for a myriad of energy technologies.
Keywords: carbon nanofibers; coordination chemistry engineering; electrospinning; hydrogen evolution reaction; single-atom catalysis.