Nanoporous Iridium-Based Alloy Nanowires as Highly Efficient Electrocatalysts Toward Acidic Oxygen Evolution Reaction

Abstract

Acidic proton exchange membrane water electrolysis is a prospective energy conversion technology for future hydrogen production. However, its wide application is limited by the excessive dependence of oxygen evolution reaction on precious metals at anode. To address this issue, herein, we report a class of IrM (M = Ni, Co, Fe) catalysts with diluted Ir content fabricated via a eutectic-directed self-templating strategy. Manipulated by the eutectic reaction and dealloying inheritance effect, the IrM catalysts show a unique network structure composed of intertwining nanoporous nanowires. The catalytic activities of IrM nanowires show a transition-metal-dependent feature, among which IrNi delivers the best activity with an exceptionally low overpotential to drive 10 mA cm^-2 (283 mV) and a high mass activity at 1.53 V vs reversible hydrogen electrode (0.732 A mg^-1). Such performance represents a major leap forward compared to that of commercial IrO₂ and most of state-of-the-art Ir-based acidic catalysts toward oxygen evolution reaction. First-principles calculations indicate that the 3d transition-metal-dependent catalytic activity of IrM electrocatalysts is related to ligand effect, wherein the negative shift of Ir d-band center after alloying can effectively weaken the adsorption of reaction intermediates.