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

The combination of 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 BiO2-x nanosheets was successfully manufactured and carried out to activate peroxymonosulfate (PMS) for the removal of ciprofloxacin (CIP). Here, with the help of visible light, the optimal Cu-doped BiO2-x nanosheet (CBO-1) activating PMS for the removal of CIP has a degradation rate 4.64 times more than that of BiO2-x. Photo/electro-chemical characterizations 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 Cu center with poor electrons was prone to form Cu ligands with CIP for enhancing the reduction of Cu(II) to accelerate the activation of PMS. Therefore, this work proposes a thinking on synthesizing efficient semiconductor photocatalysts for activating PMS, providing a valuable reference for the efficient mineralization of recalcitrant contaminant in water.