Abstract
The surface modification of semiconductor photoelectrodes with passivation overlayers has attracted great attention as an effective strategy to improve the charge separation and charge transfer processes across the semiconductor-electrolyte interface. In this work, a thin Fe2TiO5 layer was decorated on nanostructured hematite nanoflake and nanocoral photoanodes (by thermal oxidation of iron foils) by a facile water-based solution method. Photoelectrochemical measurements show that the Fe2O3/Fe2TiO5 heterostructure exhibits an obvious enhancement in photoelectrochemical water oxidation performance compared to the pristine hematite. For example, at 1.23V versus the reversible hydrogen electrode (V-RHE) in 1m KOH under AM1.5G (100mWcm(-2)) illumination, a 4-8x increase in the water oxidation photocurrent is achieved for Fe2O3/Fe2TiO5, and a considerable cathodic shift of the onset potential up to 0.53-0.62V(RHE) is obtained. Moreover, the performance of the Fe2O3/Fe2TiO5 heterostructure can be further improved by decoration with a SnOx layer. The enhancement in photocurrent can be attributed to the synergistic effect of Fe2TiO5/SnOx overlayers passivating surface states, and thus reducing surface electron-hole recombination.