Adjustable heterointerface-vacancy enhancement effect in RuO2@Co3O4 electrocatalysts for efficient overall water splitting

Revealing the nature of enhanced catalytic activity by oxygen vacancy and hetero-interface is an important and challenging task. Herein, the high-performance RuO 2 @Co 3 O 4 electrocatalyst with adjustable heterointerface-vacancy enhancement effect was prepared for the first time. The as-prepared RuO 2 @Co 3 O 4 (1:6) only respectively requires overpotentials of 152, 218 mV for OER and 90, 33 mV for HER in alkaline and acidic solutions to achieve a current density of 10 mA cm −2 . Moreover, the assembled electrolytic cell just need a voltages of 1.46, 1.65 V and 1.52, 1.72 V to achieve 10 and 350 mA cm −2 under the same conditions. The different ratios of Ru and Co can regulate the number of hetero-interfaces between RuO 2 and Co 3 O 4 and the concentration of interfacial oxygen vacancies. The systematically experimental and theoretical results unveil that the hetero-interface with strong electron coupling between RuO 2 and Co 3 O 4 accelerates the reaction kinetic and improves the stability of the catalyst. The interfacial oxygen vacancy not only directly participates in the reaction of dissociating H 2 O, but also adjusts the position of the d-band center of the catalyst and the adsorption strength of key intermediates, thus enhancing the activity of the catalysts.