Use of a core-shell composite Ag 3 PO 4 @TCNQ to improve photocatalytic activity and stability

Abstract We report a composite photocatalyst with a core-shell structure of Ag 3 PO 4 @TCNQ (7,7,8,8-Tetracyanoquinodimethane). TCNQ nano-sheet with a conjugated structure was coated on Ag 3 PO 4 particles to enhanced photocatalysis and the stability of Ag 3 PO 4 . This composite catalyst can improve the contact area between semiconductors, promote the separation efficiency of electron and hole, and improve photocatalytic activity and stability. Ag 3 PO 4 @TCNQ exhibited a high degradation of phenol under visible light. The degradation rate of Ag 3 PO 4 @TCNQ (0.3 wt.%) to degradation phenol achieved almost 100% in 12 min, which was about 23% higher than that of pure Ag 3 PO 4 . In addition, TCNQ wrapped on Ag 3 PO 4 surface, as the core’s protective layer, can effectively improve its stability. After five cycles, the degradation rate still reached 90%, but monomer stability retained only 43%. TCNQ, as a good electron acceptor, can transfer electrons from Ag 3 PO 4 surface well, reduce the reduction of Ag + , and improve the separation efficiency of photogenerated charge, greatly improving the activity and stability of catalyst. TCNQ has a positive position of its energy band relative to Ag 3 PO 4 , and the electrons on the Ag 3 PO 4 conduction band can easily transform to the Lowest Unoccupied Molecular Orbital (LUMO) level of TCNQ to realize the efficient separation of charge, which effectively improve quantum efficiency, thus improving activity and stability of catalyst.