Dual Modification Strategy: Passivation Layer and Cocatalyst on Hematite for Improved Photoelectrochemical Water Oxidation.

α-FeO is a very attractive photoanode for photoelectrochemical (PEC) water decomposition. However, its short diffusion length, poor conductivity, and fast charge-carrier recombination severely limit device efficiency. Here, coloading an AlO passivation layer and a CoO cocatalyst onto Ti-doped α-FeO was carried out to promote PEC water oxidation by improving charge separation and transfer at the electrode/electrolyte interface and inhibiting photocarrier recombination. The optimized Ti:FeO/AlO/CoO photoanode shows a large photocurrent density of 1.41 mA cm at 1.23 V vs reversible hydrogen electrode, which is 47 times greater than that of a pristine Ti:FeO photoanode. The dual modifications with a combined passivation layer and cocatalyst on the photoanode verify a valuable way for solar energy conversion in PEC water oxidation.