Perfect inhibition of CdS photocorrosion by graphene sheltering engineering on TiO2 nanotube array for highly stable photocatalytic activity

Abstract

An artful graphene sheltering engineering onto TiO₂ nanotube array for perfect inhibition of CdS photocorrosion (RGO/CdS–TiO₂ NT) has been developed by a one-step electrodeposition method. The CdS photocorrosion driven by both holes and radicals has been systematically investigated and identified. The RGO layer provides a perfect protection to CdS through (i) blocking the attack of active species especially ˙OH radicals and (ii) offering a closed electron-rich microenvironment where the stored electrons RGO(e⁻) not only reduce intermediate species S˙⁻ to S²⁻ but also compensate the valence band of CdS for its loss of electrons to alleviate CdS photocorrosion from oxidation by holes. The photocatalyst exhibits extremely high stability. RGO/CdS–TiO₂ NT shows high visible-light photocatalytic activity for the degradations of organic dye methylene blue (MB), industrial chemical p-nitrophenol (PNP) and herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). This work provides a new insight into the protection of photosensitive semiconductors from photocorrosion.