Balancing hydrogen adsorption/desorption by orbital modulation for efficient hydrogen evolution catalysis

摘要

Hydrogen adsorption/desorption behavior plays a key role in hydrogen evolution reaction (HER) catalysis. The HER reaction rate is a trade-off between hydrogen adsorption and desorption on the catalyst surface. Herein, we report the rational balancing of hydrogen adsorption/desorption by orbital modulation using introduced environmental electronegative carbon/nitrogen (C/N) atoms. Theoretical calculations reveal that the empty d orbitals of iridium (Ir) sites can be reduced by interactions between the environmental electronegative C/N and Ir atoms. This balances the hydrogen adsorption/desorption around the Ir sites, accelerating the related HER process. Remarkably, by anchoring a small amount of Ir nanoparticles (7.16?wt%) in nitrogenated carbon matrixes, the resulting catalyst exhibits significantly enhanced HER performance. This includs the smallest reported overpotential at 10?mA?cmsup-2/sup (4.5?mV), the highest mass activity at 10?mV (1.12?A mgsubIr/subsup-1/sup) and turnover frequency at 25?mV (4.21 Hsub2/sub ssup-1/sup) by far, outperforming Ir nanoparticles and commercial Pt/C.