Simulated solar driven catalytic degradation of psychiatric drug carbamazepine with binary BiVO4 heterostructures sensitized by graphene quantum dots

•GQD/BiVO4 composites could significantly enhance the solar-driven photocatalytic activities for CBZ.•Multi-factors influencing degradation process were investigated.•Potential transformation products during the degradation process were tentatively identified.•Hydroxylation or cleavage of amide group on the heterocycle may be the main initial photocatalytic degradation channels.

Herein, solar-driven GQDs loaded BiVO4 heterostructure catalysts were fabricated and employed to degradate carbamazepine (CBZ) under simulated solar light. The as-prepared ternary catalysts (GQD/m-BiVO4/t-BiVO4) were thoroughly characterized by TEM, HRTEM, XRD, XPS, UV-vis, Raman and PL. The characterization results demonstrated that GQDs are well-dispersed on binary BiVO4 support, and the optical properties of the composites are improved with GQDs loaded. The photocatalytic activities of the novel composite catalysts were significantly increased by incorporation of GQDs on original BiVO4 semiconductor. In particular, the 1.0 wt% GQD loaded catalysts exhibited the highest photocatalytic activity for CBZ, and the mineralization degree of CBZ with the catalysts could achieve more than 95%. In addition, the transformation products (TPs) of CBZ during the catalysis processes were tentatively identified, and hydroxyl radicals were regarded as the predominant active species. From the results of density functional theory (DFT) calculations and evolution of TPs, hydroxylation and cleavage of amide group on the heterocycle may be the main initial photocatalytic degradation channels for CBZ under the catalysis of GQD/BiVO4.

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