The Z-scheme heterojunction between TiO2 nanotubes and Cu2O nanoparticles mediated by Ag nanoparticles for enhanced photocatalytic stability and activity under visible light

The photocatalytic reduction method was used to introduce Ag nanoparticles (Ag NPs) into the Cu2O-TiO2 nanotubes (Cu2O-TNT) prepared by electrodeposition. The Z-scheme heterojunction Cu2O-Ag-TNT (CAT-4-60) catalysts were prepared. The mechanism of the transition from the traditional P-N heterojunction enhanced by noble metal to the Z-scheme heterojunction was studied. In addition, the Z-scheme heterojunction CAT-4-60 showed the highest light absorption and the highest photoelectrochemical activity under visible light, and the photoluminescence intensity was significantly reduced. Compared with the traditional P-N heterojunction CAT-2-60, not only the photocatalytic activity of the dual Z-scheme CAT-4-60 catalyst was improved, and the removal rate of MB was 98.58% higher than TNT (45.81%), CT-60 (69.49%), AT-2 (75.1%) and CAT-2-60 (91.2%),but also the stability of Cu2O in CAT-4-60 was significantly enhanced. This work reveals the potential application of noble metal nanoparticles to enhance the Z-scheme heterojunction under visible light-driven photocatalysis, and provides new insights to the transition from traditional P-N heterojunctions to Z-scheme heterojunctions.