Enriched electrophilic oxygen species facilitate acidic oxygen evolution on Ru-Mo binary oxide catalysts

The polymer electrolyte membrane (PEM) electrolyzers are burdened with costly iridium (Ir)-based catalysts and high operation overpotentials for the oxygen evolution reaction (OER). The development of earth-abundant, highly active, and durable electrocatalysts to replace Ir is a critical step in reducing the cost of green hydrogen production. Here we develop a Ru5Mo4Ox binary oxide catalyst that exhibits high activity and stability in acidic OER. The electron-withdrawing property of Mo enriches the electrophilic surface oxygen species, which promotes acidic OER to proceed via the adsorbate evolution pathway. As a result, we achieve a 189 mV overpotential at 10 mA center dot cm(-2) and a Tafel slope of 48.8 mV center dot dec(-1). Our catalyst demonstrates a substantial 18-fold increase in intrinsic activity, as evaluated by turnover frequency, compared to commercially available RuO2 and IrO2 catalysts. Moreover, we report a stable OER operation at 10 mA center dot cm(-2) for 100 h with a low degradation rate of 2.05 mV center dot h(-1).

Automated summary

The development of a Ru5Mo4Ox binary oxide catalyst as a replacement for expensive iridium-based catalysts in acidic oxygen evolution reaction (OER) has shown high activity and stability, resulting in a reduction in the cost of green hydrogen production.