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 RuO2@Co3O4 electrocatalyst with adjustable heterointerface-vacancy enhancement effect was prepared for the first time. The as-prepared RuO2@Co3O4(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 RuO2 and Co3O4 and the concentration of interfacial oxygen vacancies. The systematically experimental and theoretical results unveil that the hetero-interface with strong electron coupling between RuO2 and Co3O4 accelerates the reaction kinetic and improves the stability of the catalyst. The interfacial oxygen vacancy not only directly participates in the reaction of dissociating H2O, 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.