Investigation of Photoelectrochemical Water Splitting for Mn-Doped In2O3 Film

Abstract

Undoped and Mn-doped In2O3 films were prepared by radiofrequency magnetron sputtering technique. The effects of Mn doping on the structural and optical properties of as-prepared films were investigated using X-ray diffraction, X-ray photoelectron spectroscopy and ultraviolet–visible spectroscopy. Mn doping can enhance the intensity of (222) peak in Mn-doped In2O3 thin film, indicating Mn dopant promotes preferred orientation of crystal growth along (222) plane. XPS analyses revealed that the doped Mn ions exist at + 2 oxidation states, substituting for the In3+ sites in the In2O3 lattice. UV–Vis measurements show that the optical band gap Eg decreases from 3.33 to 2.87 eV with Mn doping in In2O3, implying an increasing sp–d exchange interaction in the film. Our work demonstrates a practical means to manipulate the band gap energy of In2O3 thin film via Mn impurity doping, and significantly improves the photoelectrochemical activity.