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

Abstract

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 photocatalytic 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.