In Situ Grown RuNi Alloy on ZrNiN_x as a Bifunctional Electrocatalyst Boosts Industrial Water Splitting.

Abstract

Alkaline water electrolysis represents a pivotal technology for green hydrogen production yet faces critical challenges including limited current density and high energy input. Herein, a heterostructured bimetallic nitrides supported RuNi alloy (RuNi/ZrNiN_x) is developed through in situ epitaxial growth under ammonolysis, achieving exceptional bifunctional activity and durability for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 m KOH electrolyte. The RuNi/ZrNiN_x exhibits a HER current density of -2 A cm^-2 at an overpotential of 392.8 mV, maintaining initial overpotential after 1000 h continuous electrolysis at -500 mA cm^-2. For OER, it delivers a current density of 2 A cm^-2 at 1.822 V versus RHE, and sustains stable operation for 705 h at 500 mA cm^-2. Experimental and theoretical studies unveil that the charge redistribution-induced high-valence Zr centers effectively polarize H─O bonds and promote water dissociation, and the electron-deficient interface Ru sites optimize hydrogen desorption kinetics. Dynamic OH spillovers from Zr sites to the adjacent tri-coordinated Ni hollow sites in NiN_x promote rapid *OH intermediate desorption and active site regeneration. Notably, the tri-coordinated Ni hollow sites in NiN_x proximal to Zr atoms exhibit tailored adsorption strength for oxo-intermediates, enabling a more energetically favorable pathway for O₂ production.