Synergistic electronic and morphological modulation by trace Ir introduction boosting oxygen evolution performance over a wide pH range

Simultaneous realization of enhanced activity, improved stability, and lowered cost remains desirable yet challenging in the exploration of electrocatalysts for oxygen evolution reaction (OER) over a wide pH range. Herein, we report hierarchical Co nanorod arrays (NRAs) incorporated with trace amount of Ir (1.0 at%) (IrCo NRAs), display excellent OER activity, with overpotentials of 257.3, 296.9 and 376.1 mV at 10 mA cm(-2) in 1.0 M KOH, 0.5 M H2SO4 and 1.0 M phosphate buffered saline, respectively. Moreover, the hierarchical IrCo NRAs exhibit extraordinary pH-universal stability. The experimental characterizations and theoretical calculations reveal the dramatic enhancement of OER performance is mainly attributed to the introduction of trace amount of Ir, leading to the modulated morphological and electronic structure as well as reduced OER energy barrier. This work paves a new avenue toward designing highly efficient OER catalysts with significantly reduced amount of precious metals in a wide pH range.