Construction of 0D/2D CuO/BiOBr hierarchical heterojunction for the enhanced photocatalytic degradation of benzene-containing pollutants under visible light

In this study, a novel CuO/BiOBr composite photocatalyst with p-n heterojunction were fabricated by a facile microwave-assisted aqueous chemical deposition strategy. The as-prepared CuO/BiOBr heterojunction is comprised of zero-dimensional (0D) CuO quantum dots (QDs) with average size of 4.1 nm uniformly grown on the 2D thin BiOBr nanoflakes (NFs) with {001}-facet exposure forming hierarchical structures. The CuO/BiOBr heterostructures exhibit greatly enhanced photocatalytic activity in the degradation of benzene-containing pollutants such as Congo red (CR) and Bisphenol A (BPA) under visible light irradiation, in which the apparent kinetic rates of the sample CB-3 to degrade CR and BPA are 4.92 and 4.64 times higher than those of the pristine BiOBr, respectively. The improved photocatalytic activity is attributed to the formation of the appropriate p-n heterojunction between p-CuO and n-BiOBr, thereby achieving higher visible light harvesting, faster transfer and separation of the photo-induced charges across the contacted interface, and larger photoactive sites for the redox reactions. The proposed spatial charge-transfer mechanism of CuO/BiOBr heterojunction is evaluated by the band measurement and the radical trapping experiments. This work provides a surface engineering strategy for the construction of advanced photocatalysts for wastewater treatment.