Enhanced photoelectric performance of rutile SnO2 by Mg-assisted S-O coupling

Abstract

The electronic structures and conducting mechanism of (Mg, S) co-doped rutile SnO2 were explored through density functional theory (DFT) calculation. Results showed that the acceptor metal Mg assisted the coupling of the incorporated S with a neighbouring O in SnO2, which introduced new energy levels into the forbidden band of SnO2 and thereby improved the photoelectric performance of SnO2. Based on this result, we proposed an integrated strategy that combines DFT calculations with experiments to study the photoelectric performance of (Mg, S) co-doped SnO2 prepared through hydrothermal method. Conducting glass (FTO) was used for the preparation of (Mg, S) co-doped SnO2 electrode. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy results confirmed the incorporation of Mg and S elements into the SnO2 cell. Furthermore, photoelectric performance tests revealed that (Mg, S) co-doping can improve photoelectric performance. The maximum photocurrent (0.50 μA/cm2) and smallest impedance were obtained at a co-doping ratio of 5%. Therefore, the (Mg, S) co-doped SnO2 is a strong candidate for photoelectrocatalysis.