Facile construction of self-supported Ru-Ni(OH)2 with built-in interfacial electric field for accelerating hydrogen evolution

Sluggish water dissociation kinetics in the alkaline hydrogen evolution reaction (HER) continue to hamper its practical production. Herein, a class of heterojunction electrocatalyst featuring Ru-Ni(OH) 2 interfaces on nickel foam (NF) with self-engineered built-in electric fields (BIEF) has been synthesized via a simple in situ galvanic replacement reaction. The as-made hierarchical architecture of Ru-Ni (OH) 2 /NF exhibits a record overpotential of 9.6 mV at a current density of 10 mA cm −2 for alkaline HER, surpassing most reported catalysts and the commercial Pt/C benchmark. Furthermore, it also reveals exceptional catalytic activity towards hydrazine oxidation reaction (HzOR) at 100 mA cm −2 with a remarkably low potential of ca. 0.015 V vs. RHE (reversible hydrogen electrode). The assembled overall hydrazine splitting (OHzS) system integrating HER and HzOR requires a cell voltage of about 0.09 V to reach 50 mA cm −2 , which is 1.637 V lower than the corresponding overall water splitting (OWS) device. Systematic analysis and calculation reveal that the BIEF induces the redistribution of interfacial electrons for Ru, facilitating H 2 O dissociation and intermediates conversion to deliver the ultra-high electrocatalytic performance. This work provides an avenue for the design and preparation of electric field-mediated catalysts towards sustainable energy conversion.