Precisely tuning the Ni3N/Pt interface to boost the catalytic activity of alkaline hydrogen evolution reaction

Abstract

The hydrogen evolution reaction (HER) in alkaline solutions does not access H* directly, resulting in a slower reaction kinetics compared to that in acidic solutions. Here, we report a Cr-doped Ni3N/Pt heterostructure that provides additional active sites to produce H* via the water-cleaving step, in addition to the intrinsic active Pt site for H* absorption. It is demonstrated that the Cr dopant can modulate the charge redistribution between Ni3N and Pt interface, lowering the energy barrier of both the Volmer step and the following Heyrovsky step. As a result, the prepared Cr-Ni3N/Pt catalyst achieves an extreme low overpotential of 20 mV to deliver a current density of 10 mA/cm2 under alkaline conditions, which is significantly better than the commercial Pt/C catalyst (45 mV). Density Functional Theory (DFT) further reveals that the Cr-modified Ni3N/Pt interface undergoes electronic orbital hybridization, enhancing the water adsorption and dissociation processes on the Ni sites. This work presents the feasibility of the electronic structure modulation in low-platinum catalysts, which provides an effective strategy for the design of electrocatalysts used in multi-step reactions.