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) hamper its practical production. Here, a heterojunction electrocatalyst featuring Ru-Ni(OH)2 interfaces on nickel foam (NF) with self-engineered built-in electric fields (BIEF) was synthesized via a simple in situ galvanic replacement reaction. The hierarchical Ru-Ni(OH)2/NF exhibits a record overpotential of 9.6 mV at 10 mA cm−2 for alkaline HER, surpassing most reported catalysts and commercial Pt/C. It also shows exceptional activity for hydrazine oxidation reaction (HzOR) at 100 mA cm−2 with a remarkably low potential of ca. 0.015 V vs. RHE. 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 redistribution of interfacial electrons for Ru, facilitating H2O dissociation and intermediate conversion, delivering ultra-high electrocatalytic performance. This work provides an avenue for design and preparation of electric field-mediated catalysts towards sustainable energy conversion.