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

Abstract

• The self-supported and hierarchical IrCo nanorod arrays with ultralow content of Ir were fabricated for oxygen evolution reaction. • The incorporation of trace amount of Ir into Co lattice induced the formation of hierarchical (nanosheet-on-nanorod) structure and modulated the electronic structure. • The IrCo catalyst exhibited excellent OER activity and stability in alkaline, acidic and neutral solution. • DFT calculations revealed the introduction of trace amount of Ir into Co changed the rate-determining step and lowered the energy barrier toward OER. 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 H 2 SO 4 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.