Visible light‐activated degradation of microcystin‐LR by ultrathin g‐C3N4 nanosheets‐based heterojunction photocatalyst

Abstract

AbstractMicrocystins (MCs) is a harmful toxin generated by blue‐green algae in water, which has seriously threatened the ecological safety of water and human body. It is urgent to develop new catalysts and techniques for the degradation of MCs. A feasible electrostatic self‐assembly method was carried out to synthesize BiVO4/g‐C3N4 heterojunction photocatalyst with highly efficient photocatalytic ability, where BiVO4 nanoplates with exposed {010} facets anchored to the g‐C3N4 ultrathin nanosheets. The morphology and microstructure of the heterojunction photocatalysts were identified by XRD, SEM, TEM, XPS, and BET. The g‐C3N4 nanosheets have huge surface area over 200 m2/g and abundant mesoporous ranging from 2‐20 nm, which provides tremendous contact area for BiVO4 nanoplates. Meanwhile, the introduction of BiVO4 led to red‐shift of the absorption spectrum of photocatalyst, which was characterized by UV‐vis diffuse reflection spectroscopy (DRS). Compared with pure BiVO4 and g‐C3N4, the BiVO4/g‐C3N4 heterojunction shows a drastically enhanced photocatalytic activity in degradation of microcystin‐LR (MC‐LR) in water. The MC‐LR could be removed within 15 minutes under the optimal ratio of BiVO4/g‐C3N4. The outstanding performance of the photocatalyst is attributed to synergetic effect of interface Z‐scheme heterojunction and high active facets {010} of BiVO4 nanoplates, which provides an efficient transfer pathway to separate photoinduced carriers meanwhile endows the photocatalysts with strong redox ability.