Self-assembled CoOOH on TiO2 for enhanced photoelectrochemical water oxidation

The as-obtained 6% CoOOH-TiO 2 photoelectrode manifests enhanced PEC performance owing to the fast carrier migration across TiO 2 to CoOOH. And the valence transition of surface amorphous CoOOH plays a dominating role in the PEC process. 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 TiO 2 . Intriguingly, the as-obtained 6% CoOOH-TiO 2 photoelectrode manifests optimal PEC performance with a high photocurrent density of 1.3 mA/cm 2 , 3.5 times higher than that of pristine TiO 2 . Electrochemical impedance spectroscopy (EIS), Tafel analysis and cyclic voltammetry (CV) methods show that the carrier transfer barrier within the electrode and the transition of Co 3+ OOH to Co 4+ OOH have the dominating effects on the PEC performance. Theoretical calculation reveals that the interface between the CoOOH and TiO 2 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.