Oxygen and Chlorine Dual Vacancies Enable Photocatalytic O2 Dissociation into Monatomic Reactive Oxygen on BiOCl for Refractory Aromatic Pollutant Removal

Room-temperature molecular oxygen (O-2) dissociation is challenging toward chemical reactions due to its triplet ground-state and spin-forbidden characteristic. Herein, we demonstrate that BiOCl of oxygen and chlorine dual vacancies can photocatalytically dissociate O-2 into monatomic reactive oxygen (center dot O-) for the ring opening of aromatic refractory pollutants toward deep oxidation. The electron-rich and geometry-flexible dual vacancies of oxygen and chlorine remarkably lengthen the O-O bond of adsorbed O-2 from 1.21 to 2.74 angstrom, resulting in the rapid O-2 dissociation and the subsequent center dot O(- )formation. During the photocatalytic degradation of sulfamethazine, the in situ-formed center dot O- plays an indispensable role in breaking the critical intermediate of pyrimidine containing a stubborn aromatic heterocyclic ring, thus facilitating the overall mineralization. More importantly, BiOCI of oxygen and chlorine dual vacancies is also superior to its monovacancy counterparts on the degradation of other refractory pollutants containing conjugated six-membered rings, including p-chlorophenol, p-chloronitrobenzene, p-hydroxybenzoic acid, and p-nitrobenzoic acid. This study sheds light on the importance of sophisticated defects for regulating the O-2 activation manner and deliveries a novel O-2 activation approach for environmental remediation with solar energy.

Automated summary

This study demonstrates the photocatalytic dissociation of molecular oxygen (O-2) using BiOCl with oxygen and chlorine dual vacancies. The dual vacancies lengthen the O-O bond, resulting in rapid dissociation and formation of reactive oxygen. This approach is effective in degrading refractory pollutants and shows potential for environmental remediation.