Significantly improve photoelectrochemical performance of Ti:Fe2O3 with CdSe modification and surface oxidation

Significant interest has been arisen to explore photoanodes for full optical absorption spectrums and good stability in photoelectrochemistry. Herein CdSe is used to modify Ti:Fe2O3 photoanode forming Ti:Fe2O3/CdSe heterojunction. Combining with an air annealing treatment, Ti:Fe2O3/CdSe exhibits a 6.5 times higher photocurrent density that of the pristine Ti:Fe2O3 to achieve 3.25 mA cm−2 at 1.2 V vs. RHE. The photoelectrochemical (PEC) stability of Ti:Fe2O3/CdSe annealed in air shows great improvement comparable to both unannealed and annealed ones in Ar. The enhancement mechanisms for both heterojunction and annealing are explored for fundamental insights, which reveal that the surface oxide layer can significantly increase the PEC stability of Ti:Fe2O3/CdSe photoanode. X-ray photoelectron spectra and transmission electron microscope results further confirms the surface oxidation on CdSe layer after annealing in air.