Iridium-copper oxide nanotubes catalyzing pH-universal oxygen evolution reaction with highly improved activity and durability via elemental substitution

Abstract

Nanotubes of Ir-Cu binary metal oxide with various composition ratios (IrxCu1-xOy with x = 0.64, 0.48 and 0.33) were prepared using electrospinning followed by thermal annealing. (IrxCu1-xOy nanotubes were investigated to be composed of rutile IrO2 phase where Cu substituted Ir sites. This elemental subsititution induced the amorphization and generation of oxygen vacancy defects in the rutile phase of IrxCu1-xOy nanotubes. Among IrxCu1-xOy series, Ir0.48Cu0.52Oy nanotubes, having a reduced noble Ir content by more than a half, showed the best activity for oxygen evolution reaction (OER) in pH-universal condition, and even outperformed the material containing only Ir, commercial Ir/C and the other Ir-based binary metal oxide catalysts found in the literature. Of importance, Ir0.48Cu0.52Oy presented an excellent stability during continuous OER for 20,000 s in all the acidic, neutral and alkaline media despite their amorphousness. The introduction of Cu into IrO2 was beneficial for improving not only the OER catalytic activity but the durability along with cost-effectiveness.(c) 2022 Elsevier B.V. All rights reserved.