Ultrathin amorphous NaIrRuOx nanosheets with rich oxygen vacancies for efficient acidic water oxidation

Abstract

Developing highly active and durable catalysts for H2O/O2 conversion is particularly important in water electrolyzers for renewable hydrogen energy. Herein, we prepared ultrathin amorphous NaIrRuOx nanosheets (NSs) with a thickness of 1.2 nm with a large number of oxygen vacancies using a simple molten salt method. The NaIrRuOx NSs exhibits a low overpotential (η10, 10 mA cm−2) of 214 mV, and 8.6 and 45.7 times enhanced mass activitynoble metal at 1.53 V vs. RHE, as compared to the commercial RuO2 and IrO2, respectively. Furthermore, the NaIrRuOx NSs shows excellent corrosion and oxidation resistance in acidic oxygen evolution reaction (OER), as confirmed by a negligible potential increase after 100 h of continuous electrolysis. In a homemade PEMWE, a membrane electrode using NaIrRuOx NSs as the anode catalyst can achieve cell voltages of 1.74 V at 1 A cm−2 and operate stably at 1 A cm−2 for 350 h. Theoretical calculations indicated that the intercalation of Na+ into IrRuOx weakens the adsorption strength of OER intermediates, thus reducing the energy consumption in the conversion from O* to OOH*, and thus significantly improving the OER performance.