Substitutionally Dispersed High-Oxidation CoOx Clusters in the Lattice of Rutile TiO2 Triggering Efficient Co-Ti Cooperative Catalytic Centers for Oxygen Evolution Reactions

The development of economical, highly active, and robust electrocatalysts for oxygen evolution reaction (OER) is one of the major obstacles for producing affordable water splitting systems and metal-air batteries. Herein, it is reported that the subnanometric CoOx clusters with high oxidation state substitutionally dispersed in the lattice of rutile TiO2 support (Co-TiO2) can be prepared by a thermally induced phase segregation process. Owing to the strong interaction of CoOx clusters and TiO2 support, Co-TiO2 exhibits both excellent intrinsic activity and durability for OER. The turnover frequency of Co-TiO2 is up to 3.250 s(-1) at overpotentials of 350 mV; this value is one of the highest in terms of OER performance among the current Co-based active materials under similar testing conditions; moreover, the OER current density loss is only 6.5% at a constant overpotential of 400 mV for 30 000 s, which is superior to the benchmark Co3O4 and RuO2 catalysts. Mechanism analysis demonstrates that charge transfer occurs between Co sites and their neighboring Ti atoms, triggering the efficient Co-Ti cooperative catalytic centers, in which OH* and O* are preferred to be adsorbed on the bridging sites of Co and Ti with favorable adsorption energy, inducing a lower energy barrier for O-2 generation.