Enriched electrophilic oxygen species facilitate acidic oxygen evolution on Ru-Mo binary oxide catalysts
Yaya Wang, Yunzhou Wen, Yumeng Cheng, Xinhong Chen, Mengjiao Zhuansun, Tongbao Wang, Jun Li, Debora Meira, Huarui Sun, Jun Wei, Jia Zhou, Yuhang Wang, Sisi He, Yuhang Wang, Sisi He
Abstract
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 Ru 5 Mo 4 O x 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·cm −2 and a Tafel slope of 48.8 mV·dec −1 . Our catalyst demonstrates a substantial 18-fold increase in intrinsic activity, as evaluated by turnover frequency, compared to commercially available RuO 2 and IrO 2 catalysts. Moreover, we report a stable OER operation at 10 mA·cm −2 for 100 h with a low degradation rate of 2.05 mV·h −1 .