Facile fabrication of Bi2GeO5/Ag@Ag3PO4 for efficient photocatalytic RhB degradation

In this study, Bi2GeO5/Ag3PO4 nano-composites were synthesized by simple two-step approach. Then, Bi2GeO5/Ag@Ag3PO4 Z-scheme heterojunction was assembled by subsequent photocatalytic processes. It was characterized using XRD, SEM, TEM, HR-TEM, EDX, SAED, XPS, PL, UV–Vis DRS, photoelectrochemical and photodegradation experiments. Results illustrated that the catalytic activity of Bi2GeO5/Ag3PO4 nano-composites is remarkably superior to those of Bi2GeO5 and Ag3PO4. The influence of Bi2GeO5 amount on the performance of the composites was also studied. Results showed that 0.1Bi2GeO5/Ag3PO4 composite exhibited the best photocatalytic efficiency for rhodamine B (RhB) degradation, and gave rise to a 96% degradation of RhB after 30 ​min visible-light irradiation. In the degradation of RhB, the apparent rate constant of 0.1Bi2GeO5/Ag3PO4 is the largest, which is 0.06836min−1. After 4 cycles, RhB degradation by 0.1Bi2GeO5/Ag3PO4 still maintained 84%, equivalent to 1.7-fold higher than that of Ag3PO4. The trapping experiments revealed that holes (h+) and superoxide anions (O- 2·) were the primary species responsible for the decomposition of RhB in 0.1Bi2GeO5/Ag3PO4. Furthermore, the mechanism of improving photocatalytic activity was proposed relied on the experiments and characterization results. The formation of Bi2GeO5/Ag@Ag3PO4 Z-scheme heterojunction by photocatalytic processes dramatically increased its photocatalytic activity and stability. Based on the aforesaid analysis, a Z-scheme reaction mechanism was proposed for the Bi2GeO5/Ag3PO4 photocatalytic degradation process. [Display omitted] •Bi2GeO5/Ag@Ag3PO4 Z-scheme heterojunction was assembled by photocatalytic processes.•The formation of Ag particles during photocatalysis enhances the catalytic activity.•The formation of Z-scheme heterojunction can be extended to other catalysts.