Oxygen Vacancy Engineering of Co3O4 Nanocrystals through Coupling with Metal Support for Water Oxidation

Oxygen vacancies can help to capture oxygen-containing species and act as active centers for oxygen evolution reaction (OER). Unfortunately, effective methods for generating a high amount of oxygen vacancies on the surface of various nanocatalysts are rather limited. Here, we described an effective way to generate oxygen-vacancy-rich surface of transition metal oxides, exemplified with Co 3 O 4 , simply by constructing highly coupled interface of ultrafine Co 3 O 4 nanocrystals and metallic Ti. Impressively, the amounts of oxygen vacancy on the surface of Co 3 O 4 /Ti surpassed the reported values of the Co 3 O 4 modified even under highly critical conditions. The Co 3 O 4 /Ti electrode could provide a current density of 23 mA cm −2 at an OER overpotential of 570 mV, low Tafel slope, and excellent durability in neutral medium. Because of the formation of a large amount of oxygen vacancies as the active centers for OER on the surface, the TOF value of the Co 3 O 4 @Ti electrode was optimized to be 3238 h −1 at an OER overpotential of 570 mV, which is 380 times that of the state-of-the-art non-noble nanocatalysts in the literature. Graphical Interface activation : An easy but effective approach to generating a rich amount of oxygen vacancies (V O ) in Co 3 O 4 nanocrystal-based oxygen evolution reaction (OER) electrodes by constructing a highly coupled interface with metallic Ti is demonstrated. Oxygen vacancies help to capture water molecules for OER in neutral electrolyte, resulting in impressively high current density and TOF value at an OER overpotential of 570 mV.