Hierarchical polypyrrole encapsulating Bi2O4 to enhance charge separation and light absorption with boosted visible light photocatalytic activity

Bi2O4, as a typical visible-light responsive photocatalyst (band gap similar to 2.0 eV), has aroused enormous attention in recent years. However, single Bi2O4 has the problem of high recombination probability of photogenerated electron-hole pairs, which inevitably hampers its photocatalytic performance. Herein, hierarchical polypyrrole encapsulated Bi2O4(Bi2O4@PPy) has been constructed via an in-situ vapor-phase polymerization method, producing PPy tightly coated Bi2O4 core-shell structure photocatalyst. Thanks to this full coating and hierarchical structure, the charges separation efficiency, and the light absorption capacity of Bi2O4@PPy hybrid are promoted, leading to obviously enhanced visible light photocatalytic activity. The optimal Bi2O4@PPy composite could be obtained through controlling the polymerization time for 9 h, whose catalytic activity is as 2.43 times as that of Bi2O4 alone. The active species trapping experiments suggest that holes play a vital role in the photo catalytic degradation process. A plausible reaction mechanism over the Bi2O4@PPy hybrid photocatalyst is also proposed based on the characterization and experimental results.

Automated summary

Hierarchical polypyrrole encapsulated Bi2O4 has been constructed to enhance visible light photocatalytic activity through improving charge separation efficiency and light absorption capacity. The optimal Bi2O4@PPy composite showed 2.43 times higher catalytic activity compared to Bi2O4 alone, with holes playing a vital role in the photocatalytic degradation process. The proposed reaction mechanism is based on characterization and experimental results.