Constructing thin BiOCl nanoplates for highly efficient photocatalytic peroxymonosulfate activation: In-depth understanding of the activation process

Photocatalytic peroxymonosulfate (PMS) activation on semiconductors is attractive for remediation of wastewaters containing refractory organic pollutants because of the synergies between photocatalysis and PMS activation. However, the PMS activation route and the main reactive species are unclear and seek of highly active and stable catalysts is desirable. In this work, for the first time, BiOCl semiconductors with different morphologies are utilized for photocatalytic activation of PMS under simulated solar light to degrade carbamazepine (CBZ). Thin BiOCl nanoplates synthesized in water/ethylene glycol mixed solvents exhibit superior performances with high activities, good applicability in a wide pH range and excellent stability. The addition of PMS can dramatically accelerate (2.5 times higher) the CBZ degradation rate compared with the photocatalysis on BiOCl. The possible activation routes are carefully discussed. PMS is predominantly activated by the photo-generated electrons, not the O2− and not the holes. Serving as an electron acceptor, PMS can effectively consume electrons to inhibit the recombination of electron-hole pairs, weaken the photo-etching of BiOCl and generate additional SO4−/HO to facilitate CBZ degradation. Rather than the SO4−/HO generated from PMS, O2− and holes produced from photocatalysis are the main reactive species to dominate the degradation. The main function of PMS is to improve the intrinsic photocatalytic performance of BiOCl. This work reveals the activation route of PMS and the realistic function of PMS in photocatalysis, which would be valuable for understanding the mechanism of photocatalytic PMS activation and for designing efficient catalysts.