Influence of OH-related defects on the performances of BiPO4 photocatalyst for the degradation of rhodamine B

BiPO4 photocatalysts with different concentration of OH-related defects were synthesized for various hydrothermal time. The influence of the OH groups on photocatalytic activity, mineralization and degradation process of RhB was discussed in detail excluding other factors such as BET surface area and nanostructures. The defects in the lattice were observed to noticeably decrease the photocatalytic activity by forming defect levels and recombination centers. These defect levels would limit the transfer of the carriers to produce hydroxyl and super oxide radicals. Furthermore, the deethylation intermediates like N,N,N0-triethyl rhodamine and N,N0-diethyl rhodamine were found to accumulate in the solution when large quantities of OH-related defects were in the BiPO4 lattice. While the cleavage of the whole chromophore occurred when small quantities of OH-related defects were in the BiPO4 lattice. The reduction of super oxide radicals influenced by the existence of defects was demonstrated to be good for deethylation process and thus resulted in a decrease of the mineralization degree.

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► The photocatalytic activity of BiPO4(72 h) for RhB is as twice as that of P25.
► The OH-related defects in BiPO4 influence photocatalytic activities, obviously.
► The OH-related defects also influence degradation process of RhB.
► BiPO4 is a representative example for common influences of OH-related defects.