Enhanced peroxymonosulfate activation by copper-doped bismuth oxides for the efficient photo-degradation of ciprofloxacin: crucial role of copper sites, theoretical calculation and mechanism insight†

The combination of a semiconductor photocatalyst mediated photocatalytic reaction and persulfate activation is considered as a promising way to achieve efficient degradation of recalcitrant organic pollutants in water. Here, a series of Cu-doped BiO_2−x nanosheets were successfully manufactured and used to activate peroxymonosulfate (PMS) for the removal of ciprofloxacin (CIP). Here, with the help of visible light, the optimal Cu-doped BiO_2−x nanosheets (CBO-1) activating PMS for the removal of CIP have a degradation rate 4.64 times more than that of BiO_2−x. Photo/electro-chemical characterization and theoretical calculations have demonstrated that the introduction of Cu can also increase the electron density near the Fermi level, which accelerates the separation and movement of photo-generated carriers of photocatalysts, and then reduces the activation energy barrier of PMS and improves its utilization efficiency. Besides, the electron-poor Cu center was prone to form Cu ligands with CIP and enhance the reduction of Cu(II) to accelerate the activation of PMS. Therefore, this work proposes a method for synthesizing efficient semiconductor photocatalysts for activating PMS, providing a valuable reference for the efficient mineralization of recalcitrant contaminants in water.