Self-assembled CoOOH on TiO2 for enhanced photoelectrochemical water oxidation

Providing efficient charge transfer through the interface between the semiconductor and co-catalyst is greatly desired in photoelectrocatalytic (PEC) energy conversion. Herein, we excogitate a novel and facile means, via electrochemical activation, to successfully load the amorphous CoOOH layer architecture onto the surface of TiO2. Intriguingly, the as-obtained 6% CoOOH-TiO2 photoelectrode manifests optimal PEC performance with a high photocurrent density of 1.3 mA/cm(2), 3.5 times higher than that of pristine TiO2. Electrochemical impedance spectroscopy (EIS), Tafel analysis and cyclic voltammetry (CV) methods show that the carrier transfer barrier within the electrode and the transition of Co3+OOH to Co4+OOH have the dominating effects on the PEC performance. Theoretical calculation reveals that the interface between the CoOOH and TiO2 improves the homogeneity of effective d-orbital electronic-transfer ability among Co sites. This research sheds light on the water oxidation reaction and the design of more favorable PEC co-catalysts. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press.