Non-noble metallic Cu with three different roles in a Cu doped ZnO/Cu/g-C3N4 heterostructure for enhanced Z-scheme photocatalytic activity

Doping, co-catalyst, and Z-scheme configuration are three potential approaches to enhance the photocatalytic activity of metal oxides. Herein, a Cu doped ZnO/Cu/g-C3N4 heterostructure is prepared using the calcination-hydrothermal method. The successful fabrication is confirmed using different analytical techniques. XRD and XPS analyses reveal the presence of Cu in two chemical states, Cu2+ and Cu-0. Cu plays three roles in the Cu doped ZnO/Cu/g-C3N4 photocatalyst, as a dopant reducing the bandgap of ZnO, as an electron mediator facilitating the Z-scheme charge transport pathway, and as a co-catalyst enhancing the catalytic activity. Therefore, the Cu doped ZnO/Cu/g-C3N4 heterostructure exhibits higher photocatalytic activity than the single and binary photocatalysts. The optimized heterostructure degrades 99% of RhB and 98% of MB after 60 and 20 min respectively sunlight irradiation. Scavenger and photoluminescence experiments are used to investigate the charge separation, Z-scheme configuration, and main active species. LC-MS is employed to explore the Rh B pathway degradation. This work opens a new pathway for the investigation of the multiple roles of nonnoble metals in enhancing the photocatalytic activity.

Automated summary

The study prepared a Cu-doped ZnO/Cu/g-C3N4 heterostructure, effectively enhancing photocatalytic activity, with Cu playing a key role in reducing bandgap, facilitating charge transport, and enhancing catalytic activity. The presence of Cu in different chemical states has been confirmed through various analytical techniques, leading to improved degradation of organic dyes under sunlight irradiation.