Ohmic Contact Heterostructures Immobilized Pt Single Atoms for Boosting Alkaline Hydrogen Evolution Reaction

Abstract

Pt single-atoms catalysts have been widely confirmed as ideal electrocatalysts for high-efficiency hydrogen evolution reaction (HER), but their activity and durability at high current density remain great challenges, especially in alkaline media. Herein, a unique Ohmic contact heterostructure is fabricated by integrating Ni and NiO to immobilize Pt single-atoms (Ni-NiO-Pt) via Pt-O₄ coordination for boosting the alkaline HER. Owing to transient high temperature and pressure in the laser ablation process, Ohmic contact heterojunctions are constructed at the interfaces between metal Ni core and nanoporous semiconducting NiO shell with adequate oxygen vacancies. The large work function difference triggers the electron transfer from Ni to Pt-decorated NiO, which dramatically eliminates the electron conduction impedance and regulates the charge redistribution. Density functional theory calculation unveils that the multiple regulations of energy barrier and charge redistribution on Ohmic contact endow Ni-NiO-Pt with outstanding electrical conductivity and favorable hydrogen binding energy. Consequently, Ni-NiO-Pt displays superior alkaline HER performances with an overpotential of 23.54 mV at 10 mA cm⁻² and protruding durability for 75 h at 500 mA cm⁻², drastically outperforming commercial Pt/C and most reported HER electrocatalysts. The immobilization of Pt single-atoms on Ohmic contact opens up an avenue toward the rational design of high-efficiency electrocatalysts.