D-Orbital-Modulated Ruthenium Embedded within Functionalized Hollow MXene Networks for Enhanced Hydrazine-Assisted Hydrogen Production

Abstract

Electrochemical green hydrogen production via water splitting is an attractive and sustainable pathway; however, the sluggish kinetics of anodic oxygen evolution reaction is still a critical challenge. In this study, an effective electrocatalyst engineering approach is demonstrated by preparing an innovative hybrid of ruthenium d-orbitals-regulated nanoclusters embedding within functionalized hollow Ti₃C₂ MXene networks (Ru_0.91Ni_0.09-N/O-Ti₃C₂) to promote the hydrazine-assisted hydrogen production. A specific charge redistribution is revealed, locally concentrating at interfaces derived from stable Ru(Ni)-N/O-Ti coordination and d–p orbital hybridization. The charge transfer effect from Ni to Ru within Ru_0.91Ni_0.09 structure and Ru_0.91Ni_0.09 to N/O-Ti₃C₂ tailors electronic features of Ru sites to enable reasonable adsorption/desorption toward reactant intermediates. The Ru_0.91Ni_0.09-N/O-Ti₃C₂ requires an overpotential of only 29.3 mV for cathodic hydrogen evolution and a low potential of −29.9 mV for anodic hydrazine oxidation to reach 10 mA cm⁻², showing excellent stability. The hydrazine-assisted hydrogen production system based on Ru_0.91Ni_0.09-N/O-Ti₃C₂ electrodes delivers small cell voltages of 0.02 V at 10 mA cm⁻² and 0.92 V at industrial current level of 1.0 A cm⁻². This work may open a new electrocatalysis strategy from lab scale to industry for robust and efficient green hydrogen production.