Construction of direct Z-scheme g-C3N4/TiO2 nanorod composites for promoting photocatalytic activity

Direct Z-scheme g-C3N4/TiO2 nanorod composites were prepared for enhancing photocatalytic activity for pollutant removal. The characterization revealed that the g-C3N4/TiO2 nanorod composite formed a close interface contact between g-C3N4 and TiO2 nanorods, which was of benefit for the charge transfer and resulted in its high photocatalytic activity. The g-C3N4/TiO2 nanorod composites exhibited higher photocatalytic activity for degradation of Rhodamine B (RHB) than bare g-C3N4 and TiO2 nanorods. The high photocatalytic activity of g-C3N4/TiO2 nanorod composites is attributed to the formation of the direct Z-scheme system, in which the electrons from the conduction band (CB) of TiO2 combine with the holes from the valence band (VB) of C3N4 while the electrons from the CB of C3N4 and holes from the VB of TiO2 with stronger redox ability are used to reduce and oxidize pollutants. Based on the radical-trapping experiments, the main reactive species for RHB degradation are O-2(-) and center dot OH, which are produced by photoinduced electrons and holes with high redox ability. This work provides insights into the photocatalytic mechanism of composite materials for the photocatalytic removal of organic pollutants.