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

Abstract

Room-temperature molecular oxygen (O2) 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 O2 into monatomic reactive oxygen (•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 O2 from 1.21 to 2.74 Å, resulting in the rapid O2 dissociation and the subsequent •O– formation. During the photocatalytic degradation of sulfamethazine, the in situ-formed •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, BiOCl 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 O2 activation manner and deliveries a novel O2 activation approach for environmental remediation with solar energy.

Surface Boronizing Can Weaken the Excitonic Effects of BiOBr Nanosheets for Efficient O2 Activation and Selective NO Oxidation under Visible Light Irradiation

“…To address this huge hurdle, nature has evolved families of metalloproteins bearing unpaired d-electrons to metabolize O 2 through stepwise reduction . Inspired by the functionality of metalloproteins, heterogeneous catalysts (noble metals or transition metal oxides) with redox centers have been developed for artificial O 2 activation, which, however, usually suffer from harsh reaction conditions (high temperature) or high cost. − With the employment of low-cost semiconductors as catalysts and solar light as the energy source, the photocatalytic activation of O 2 to radical or anionic reactive oxygen species (ROS: • O – , • O 2 – , • O 2 2– ) mediated by photoelectrons provides a more environmentally friendly and cost-effective alternative. − …”

“…A complete photocatalytic O 2 activation involves the generation of energetic electrons and holes (∼fs), separation of electron–hole pairs (ps∼ns), and the population of O 2 ′s π antibonding orbital by photoelectrons (ns∼ms). − Through this process, the O–O bond of O 2 can be activated along with the antibonding orbitals by electrons to generate transient • O, • O 2 – , or • O 2 2– species, which can break the stubborn aromatic heterocyclic ring of chlorophenols or triazine herbicides, allowing for deep oxidation and suppressing the production of undesirable products (Scheme a). , The spatial electron–hole separation is usually regarded as the rate-determining step because most electrons tend to recombine with holes in the bulk (several ps) before reaching the surface reactive sites. To inhibit the recombination of electron–hole pairs, plenty of work has been devoted to shortening the transportation distance of charge carriers.…”

“…• O 2 − , or • O 2 2− species, which can break the stubborn aromatic heterocyclic ring of chlorophenols or triazine herbicides, allowing for deep oxidation and suppressing the production of undesirable products (Scheme 1a). 8,17 The spatial electron− hole separation is usually regarded as the rate-determining step because most electrons tend to recombine with holes in the bulk (several ps) before reaching the surface reactive sites. To inhibit the recombination of electron−hole pairs, plenty of work has been devoted to shortening the transportation distance of charge carriers.…”

Electronic Control of Traditional Iron–Carbon Electrodes to Regulate the Oxygen Reduction Route to Scale Up Water Purification

“…Advanced oxidation processes (AOPs) are appealing treatment options as decentralized approaches to overcome the above-mentioned fundamental obstacles. AOPs can efficiently produce powerful oxidizing HO • to oxidize recalcitrant and toxic pollutants under ambient conditions. − However, most of the traditional AOPs required substantial chemical input that far limited the development as next-generation water treatment technologies. − …”

CeO2/Ni-MOF with Synergistic Function of Enrichment and Activation: Efficient Reduction of 4-Nitrophenol Pollutant to 4-Aminophenol

“…4-Nitrophenol (4-NP), one of the main organic pollutants with hypertoxicity and refractory effects, is widely derived from pesticides, plastics, and other chemical industries. 8,9 4-Aminophenol (4-AP) is a fine-chemical intermediate, indispensable in the manufacture of dyes and pharmaceuticals. 10−12 Therefore, reducing 4-NP to 4-AP can not only remove a water pollutant but also produce a highvalue-added chemical.…”