Charge redistribution within platinum–nitrogen coordination structure to boost hydrogen evolution

Abstract

The manipulation of central atom coordination environments can greatly boost catalytic performances and promote the understanding of associated mechanisms in both sub-nanometer clusters and atomically dispersed catalysts. In this study, sub-nanometer “raft”-like PtNx clusters were synthesized on a TiO2 support, and the significant enhancement effects of the Pt–N coordination structure on the performance of hydrogen evolution reaction (HER) are demonstrated. In acidic media, the PtNx catalyst display a superior HER activity (37.5 A mg-1 Pt) and turnover frequencies (37.9H2 s-1) at overpotential of 50 mV; outperforming commercial Pt/C by a factor of 13.3 and 3.9, respectively. Density functional theory (DFT) calculation results reveal that the charge transfer occur from the N to the neighboring Pt atoms when the hydrogen is adsorbed on N atoms; such a charge redistribution within Pt–N coordination structure leads to a smaller H* free energies on the activated N atoms, and is believed to account for the higher HER activity.