Ag-induced synthesis of three dimensionally ordered macroporous anatase/rutile homojunction for solar light-driven Z-scheme photocatalysis

Z-scheme composites are considered as desirable photocatalysts. However, most of them are heterostructure and Z-scheme homojunction have been rarely reported. In this paper, for the first time, Z-scheme anatase/rutile homojunction was obtained by Ag nanoparticles (NPs) induction. Polystyrene spheres modified by Ag NPs were used as sacrificial templates to prepare three dimensionally ordered macroporous (3DOM) anatase. Incredibly, Ag NPs could induce the formation of rutile from anatase and anatase/rutile homojunction was created. High-resolution transmission electron microscopy clearly revealed the structure of anatase-Ag-rutile. Both experimental and theoretical evidences were utilized to study the induction of Ag NPs. Compared to commercial P25 and control samples, anatase-Ag-rutile composites exhibited obviously enhanced photocatalytic hydrogen evolution and disinfection under simulated solar light. The enhanced photocatalytic activities could be mainly attributed to the Z-scheme electron migration mechanism in ternary composites, which was confirmed via active species trapping experiment, electron spin resonance spectra and surface redox reactions.