Peroxydisulfate Activation and Singlet Oxygen Generation by Oxygen Vacancy for Degradation of Contaminants

Abstract

Oxygen vacancies (OVs) play a crucial role in the catalytic activity of metal-based catalysts; however, their activation mechanism toward peroxydisulfate (PDS) still lacks reasonable explanation. In this study, by taking bismuth bromide (BiOBr) as an example, we report an OV-mediated PDS activation process for degradation of bisphenol A (BPA) employing singlet oxygen (1O2) as the main reactive species under alkaline conditions. The experimental results show that the removal efficiency of BPA is proportional to the number of OVs and is highly related to the dosage of PDS and the catalyst. The surface OVs of BiOBr provide ideal sites for the inclusion of hydroxyl ions (HO–) to form BiIII–OH species, which are regarded as the major active sites for the adsorption and activation of PDS. Unexpectedly, the activation of PDS occurs through a nonradical mechanism mediated by 1O2, which is generated via multistep reactions, involving the formation of an intermediate superoxide radical (O2 •–) and the redox cycle of Bi­(III)/Bi­(IV). This work is dedicated to the in-depth mechanism study into PDS activation over OV-rich BiOBr samples and provides a novel perspective for the activation of peroxides by defective materials in the absence of additional energy supply or aqueous transition metal ions.

Oxygen Vacancy-Induced Nonradical Degradation of Organics: Critical Trigger of Oxygen (O2) in the Fe–Co LDH/Peroxymonosulfate System

“…After the reaction proceeds to 60 min, BPA and resorcinol are almost degraded, different from the degradation of BA (∼58%), which is a typical probe for SO 4 •– . The selective degradation of organics, as well as less contribution of SO 4 •– , suggests that it might be a nonradical-dominant oxidation process . In addition, the TOC removal efficiencies (Figure S11a) are ∼49, ∼37, ∼36, ∼30, ∼25, and ∼19% for BPA, resorcinol, phenol, 4-CP, p -nitrophenol, and BA within 60 min, respectively.…”

Revisiting the Graphitized Nanodiamond-Mediated Activation of Peroxymonosulfate: Singlet Oxygenation versus Electron Transfer

“…Our previous study discovered that ND bearing carbonyl groups could activate PMS to produce 1 O 2 for 4-chlorophenol (4-CP) removal. The proposed 1 O 2 -dominated oxidation was validated by chemical quenching, electron paramagnetic resonance (EPR) studies, and 1 O 2 probing experiments. − Furthermore, the critical role of singlet oxygenation in persulfate systems was also reported in the recent literature. ,,− For example, Zhou et al reported that benzoquinone (BQ) activated PMS to generate 1 O 2 for the elimination of sulfamethoxazole. Bu et al showed that oxygen vacancy-rich bismuth bromide promoted persulfate decomposition to produce 1 O 2 , which was responsible for bisphenol A degradation.…”

“…The proposed 1 O 2 -dominated oxidation was validated by chemical quenching, electron paramagnetic resonance (EPR) studies, and 1 O 2 probing experiments. − Furthermore, the critical role of singlet oxygenation in persulfate systems was also reported in the recent literature. ,,− For example, Zhou et al reported that benzoquinone (BQ) activated PMS to generate 1 O 2 for the elimination of sulfamethoxazole. Bu et al showed that oxygen vacancy-rich bismuth bromide promoted persulfate decomposition to produce 1 O 2 , which was responsible for bisphenol A degradation. In addition, Yin and Gao also proposed that singlet oxygenation was of paramount importance to degrading OMPs in nanocarbon/persulfate systems.…”

“…11,12,14−16 For example, Zhou et al 11 reported that benzoquinone (BQ) activated PMS to generate 1 O 2 for the elimination of sulfamethoxazole. Bu et al 14 showed that oxygen vacancyrich bismuth bromide promoted persulfate decomposition to produce 1 O 2 , which was responsible for bisphenol A degradation. In addition, Yin 15 and Gao 12 also proposed that singlet oxygenation was of paramount importance to degrading OMPs in nanocarbon/persulfate systems.…”

Thermal Disproportionation for the Synthesis of Silicon Nanocrystals and Their Photoluminescent Properties

“…The SiNCs absorbed near-UV radiation and then transferred this energy to the triplet state of the attached dyes, which increased the number of triplet states and finally enhanced the singlet oxygen generation (Beri et al, 2020). As a reactive oxidant, singlet oxygen exhibited great potential for quantities of applications, such as chemical synthesis (Manfrin et al, 2019;Karsili andMarchetti, 2020), environmental protection (García-Fresnadillo, 2018;Bu et al, 2021), and photodynamic therapy (Guo et al, 2010; Bartusik-Aebisher Osuchowski et al, 2021), and thus the application fields of SiNCs were also broadened. Photonic devices have always been another sought-after field for SiNCs with high QY value and solution processibility after functionalization.…”