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

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)-O-center dot radicals and (ii) offering a closed electron-rich microenvironment where the stored electrons RGO(e(-)) not only reduce intermediate species S-center dot to S-2 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.