Electronic modulation of iridium-molybdenum oxides with a low crystallinity for high-efficiency acidic oxygen evolution reaction

The development of high-efficiency and stable acidic oxygen evolution reaction (OER) is of great importance toward overall water splitting but challenging. Here, we report the electronic modulation of iridium oxides through the introduction of molybdenum to boost the OER performance in an acidic electrolyte. Remarkably, the prepared iridium-molybdenum oxide (IrMoOx) nanofibers with a low crystallinity through an electrospinning-calcination strategy show a superior OER activity in an acidic electrolyte with a low overpotential of 267 mV at 10 mA cm−2 compared with bare IrOx (333 mV) and MoOx (almost no OER activity) as well as the benchmark commercial IrO2 catalyst (330 mV). Furthermore, the IrMoOx nanofibers catalyst exhibits an excellent long-term stability with a slight degradation of the current density after 30 h because of the strong electronic interactions between IrOx and MoOx components. Furthermore, an overall water splitting device assembled with IrMoOx and Pt/C as electrodes delivers a cell voltage of 1.54 V at 10 mA cm−2 and desirable long-term stability, much better than Pt/C||IrO2 electrolyzer (1.66 V). This work offers a simple and efficient route to fabricate metal oxide-based electrocatalysts with bimetallic active sites, presenting a synergistic enhanced OER performance at a low pH circumstance.