Modulating 3d Orbitals of Ni Atoms on Ni-Pt Edge Sites Enables Highly-Efficient Alkaline Hydrogen Evolution

摘要

Water electrolysis operating in alkaline environments is a promising route to produce H-2 on a massive scale. In this context, designing highly-active and low-cost electrocatalysts is of great importance. Here NiPt alloys with plenty of atomically dispersed Pt at the edges to boost hydrogen evolution in alkaline solution are reported. The formed Ni-Pt atomic pairs at the edges hold engineered electronic structures by reducing the number of coordination atoms to facilitate the kinetically sluggish Volmer step, and further promote the hydrogen coupling step by providing separate active sites as well. With a Pt content of 3(at)%, this catalyst records an ultralow overpotential of 6 mV to reach the current density of 10 mA cm(-2), and delivers a current density of 68.3 mA cm(-2) at the overpotential of 30 mV, exceeding that of the commercial 20(wt)% Pt/C catalyst by a factor of 4. The aberration-corrected transmission electron microscopy and quasi-operando X-ray absorption fine structure measurements show Ni-Pt atomic pairs serve as active sites and enable the subtle adsorption/desorption balances between various intermediates (OH* and H*) during the hydrogen evolution reaction. The as-made alloys show high stability with negligible activity decay after a 12 h chronoamperometric test, addressing its feasibility in an overall water-splitting cell.