Selective-leaching method to fabricate an Ir surface-enriched Ir-Ni oxide electrocatalyst for water oxidation

Abstract

Durable and precious metal-lean electrocatalyst for water oxidation in acidic media would be of great significance for the large-scale application of acidic water electrolysis. Here, we report an Ir-Ni binary oxide electrocatalyst for the oxygen evolution reaction (OER) fabricated by acid leaching of Ni from Ni-rich composite oxides prepared using pyrolysis method. This Ni-leached binary oxide possesses Ir-enriched surface, porous morphology, and rutile phase structure of IrO2 with contracted lattice. In contrast, Ir-Ni binary oxide with the same composition prepared using simple pyrolysis method exhibits a rod-like aggregated morphology with Ni-enriched surface. Catalytic activity for OER of the Ni-leached binary oxide is higher than that of the pyrolyzed Ir-Ni oxide and pure IrO2. More importantly, the Ni-leached binary oxide exhibits much superior durability during continuous oxygen evolution process under a constant potential of 1.6 V compared with the pyrolyzed binary oxide and pure IrO2. Attributed to the Ir-rich surface and the anchor effect of inner Ni atoms to outer Ir atoms, the Ni-leached binary oxide shows a possibility of reducing the demand of the expensive and scarce Ir in OER electrocatalyst for acidic water splitting.