BiVO4/Mn3O4 a novel p–n heterojunction photocatalyst functionalized with metalloporphyrins: Synthesis, charge transfer mechanism, and enhanced visible‐light photocatalysis for degradation of dye pollutant

A simple one‐pot hydrothermal method was successfully used to synthesize p–n heterojunction Mn3O4/BiVO4 composites with different contents of BiVO4. The experimental results show that the as‐prepared p–n heterojunction Mn3O4/BiVO4 composite exhibited higher visible light photocatalytic activity for the degradation of model dye methylene blue than the pure BiVO4 and Mn3O4 crystal under irradiation of 5 W white LED lamp. The enhanced photocatalytic efficiency is due to a large number of p–n heterojunctions in Mn3O4/BiVO4 composites, which effectively reduces the recombination of the electrons and holes by charge transfer from n‐type BiVO4 to p‐type Mn3O4 crystals. The prepared p–n heterojunction Mn3O4/BiVO4 composite was functionalized with cobalt, zinc, copper, and tin complexes of porphyrin. The energy diagrams of these prepared compounds were calculated via the electrochemical investigations and the electron transfer mechanism was discussed in details. The photocatalytic efficiency of the functionalized nanocomposites enhances significantly compared to the p–n heterojunction Mn3O4/BiVO4 under visible light irradiation. Between the prepared compounds, BiVO4/Mn3O4‐CoTCPP shows higher photocatalytic activity. This compound can destruct 98% of dye pollutant in 180 min under irradiation of 5 W white LED lamp. Furthermore, this photocatalyst shows proper stability after four cycle degradation test.