Robust Ru-N metal-support interaction to promote self-powered H2 production assisted by hydrazine oxidation

Abstract

Electrocatalytic overall water splitting is hailed as the most promising approach to sustainably produce hydrogen on big scale, but the sluggish anodic oxygen evolution reaction (OER) with large operating potential results in the enormous energy consumption. To couple the cathodic hydrogen evolution reaction (HER) with low-potential hydrazine oxidation reaction (HzOR) is highly promising to significantly reduce the input cell voltage of water electrolysis, which requires high-performance bifunctional HER and HzOR electrocatalysts. Herein, a new-type Ru nanoparticle/mesoporous N-doped carbon (Ru/MPNC) composite is readily constructed with greatly exposed ultrafine Ru particles fused into N-doped carbon walls, and stabilized by in situ formed robust Ru-N metal-support interaction inherently stemming from the particular precursor, thus exhibiting superior bifunctional HER and HzOR activity, far surpassing commercial Pt/C. Furthermore, the two-electrode electrolyzer only require an ultrasmall cell voltage of 0.149 V to achieve 50 mA cm-2, which can be also easily driven by a direct hydrazine-H2O2 fuel cell to attain a decent H2 production rate of 0.893 mmol h−1. The theoretical calculations uncover the robust integration of Ru with NC can tailor the electronic property of exposed Ru sites, endowing the decreased water dissociation energy barrier, together with optimized adsorption free energies of H* and dehydrogenation intermediates of N2H4.