Enhanced photocatalytic performance of heterostructure BiOBr/PPy for Cr (VI) reduction and dye degradation

Polypyrrole-decorated BiOBr composites (BiOBr/PPy) were synthesized by in-situ polymerizations, which exhibited an excellent catalytic performance in visible-light driven Cr(VI) reduction and degradation of dye methylene blue (MB). PPy not only acted as a photosensitizer to harvest more photon for photocatalysis, but also an electric conductor for accelerating the transfer and separation of e(-)-h(+) pairs. In the as-prepared composites, the BiOBr/PPy1.5 presented the excellent photocatalytic activity, which could achieve nearly 100 % removal efficiencies for the Cr(VI) reduction after 40 min and MB degradation within 50 min. The enhanced photo -catalytic performance was ascribed to the decorating of PPy on BiOBr for maximizing the light absorption, migration and separation of photogenerated e(-)-h(+) pairs. Moreover, the possible photocatalytic mechanisms were put forward for Cr(VI) reduction and MB degradation over the BiOBr/PPy, respectively. The photogenerated electrons of PPy were readily transferred to BiOBr, and the photogenerated holes kept in PPy, resulting in a significant enhancement of the photocatalytic activity. Such designed structure offered a new way to construct a spatial separation system of charge carriers for high-efficient photocatalysts in environmental remediation.