Acid-Treated RuO<sub>2</sub>/Co<sub>3</sub>O<sub>4</sub> Nanostructures for Acidic Oxygen Evolution Reaction Electrocatalysis
Xinhui Huang, Carmen Lee, Yongdan Li, Junhua Xu, Daobin Liu
Abstract
RuO 2 is widely used as an acidic electrocatalyst to achieve high catalytic activity, but the severe leaching and scarcity of the Ru element restrict application on a large scale. Strategies such as designing nanostructures and adjusting metals’ electronic properties to regulate the adsorption of reaction intermediates can be used for the design and preparation of catalysts. Herein, we designed an acid-treated RuO 2 /Co 3 O 4 nanostructure electrocatalyst with low Ru content and an intimate heterogeneous interface to disrupt the trade-off relationship between stability and activity. The resulting acid-treated RuO 2 /Co 3 O 4 displayed an overpotential of 152 mV in a 0.5 M H 2 SO 4 electrolyte, greatly exceeding that of commercial RuO 2 (221 mV). Despite continuous operation for 150 h, it still exhibited good stability with a degradation rate of 0.67 mV·h –1 . Multiple characterization analyses revealed that an electron transfer occurs from Ru oct to Co oct (III) sites through the mutual O atoms in acid-treated RuO 2 /Co 3 O 4, which is further strengthened by the presence of oxygen vacancies. The oxygen vacancy and heterogeneous interface synergistically regulate electronic dispersion, optimize the adsorption of the oxygen intermediates (*OOH), and improve the reaction kinetics of the oxygen evolution reaction (OER). This work brings to light the significance of oxygen vacancies for modulating the electronic structure of RuO 2 nanoparticles and enhancing stability on Co 3 O 4 support, thus highlighting the use of nanostructure and interfacial engineering to achieve better acidic OER catalyst design.