Electrochemically activated Ni@Ni(OH)2 heterostructure as efficient hydrogen evolution reaction electrocatalyst for anion exchange membrane water electrolysis

Abstract

Efficient and cost-effective catalysts are vital for sustainable hydrogen production via water electrolysis. In this study, we propose a facile method of fabricating a Ni@Ni(OH)2 heterostructure catalyst on a Ti paper substrate by combining electrodeposition and subsequent electrochemical activation. Detailed characterization and analysis revealed the formation of Ni (oxy)hydroxides. Ni@Ni(OH)2 underwent surface reconstruction, resulting in the formation of abundant heterojunctions and electron modulation during electrochemical activation, which substantially increased the exposed surface area facilitating the adsorption of intermediates during the hydrogen evolution reaction (HER). Thus, the resulting activated Ni@Ni(OH)2/Ti electrode exhibited significantly improved HER activity in the half-cell test, reaching a current density of −10 mA/cm2 at an overpotential of 58 mV with a Tafel slope of 83 mV/dec. When applied to anion exchange membrane water electrolysis, a single cell comprising an Ni@Ni(OH)2/Ti cathode and commercial IrO2/CP anode exhibited a maximum current density of 1.00 A/cm2 at a potential of 2.0 Vcell, demonstrating superior performance to commercial Pt/C electrodes in the high-current-density region above 2.0 A/cm2.