Tuning electron correlations of RuO2 by co-doping of Mo and Ce for boosting electrocatalytic water oxidation in acidic media

Designing highly efficient electrocatalysts in acidic media is considered as a promising strategy for improving the wide applications of proton exchange membrane (PEM) electrolyzers. Especially, oxygen evolution reaction (OER) requires high overpotentials (eta) to overcome the high thermodynamic energy barrier toward water splitting. Herein, both Mo and Ce with large ionic radius are incorporated into RuO2 to redistribute electronic structures around Ru_O bonds, promoting the activity and stability of RuO2. The representative Ru3MoCeOx exhibits superior activity with an overpotential of 164 mV at 10 mA cm-2 and excellent stability of 100 h (100 mA cm-2) in acidic media. Density functional theory (DFT) calculations and micro characterizations reveal that introduction of Mo and Ce into RuO2 effectively tune Ru-O bonds covalency, modulate electron correlations and reduce energy barrier of the intermediates from 0.78 to 0.60 eV. The outstanding activity and long-term stability indicate that Ru3MoCeOx could be acted as efficient anode catalyst in PEM electrolyzers for water splitting.