Singlet oxygen triggered by robust bimetallic MoFe/TiO2 nanospheres of highly efficacy in solar-light-driven peroxymonosulfate activation for organic pollutants removal

• Published in: Applied catalysis. B, Environmental Vol. 286; p. 119930
• Main Authors: Dong, Chencheng, Bao, Yan, Sheng, Tian, Yi, Qiuying, Zhu, Qiaohong, Shen, Bin, Xing, Mingyang, Lo, Irene M.C., Zhang, Jinlong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.06.2021; Elsevier BV
• Subjects: Anions; Bimetallic nanoparticles; Bimetals; Biodegradation; Chlorophenol; Electrons; Environmental degradation; Free radicals; Hydroxyl radicals; Iron; MoFe/TiO2 nanospheres; Molybdenum; Nanoparticles; Nanospheres; Oxidation; Oxidation process; Oxygen; Performance degradation; Phenols; PMS; Pollutant removal; Pollutants; Redox properties; Rhodamine; Singlet oxygen; Sulfadiazine; Sulfates; Titanium dioxide; Water treatment; MoFe/TiO2 nanospheres; Singlet oxygen; Bimetallic nanoparticles; PMS
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2021.119930

[Display omitted] •Bimetallic MoFe/TiO2 nanospheres were constructed via a two-step methodology.•Both photo-generated electrons and transition metallic redox couples play vital roles in the PMS activation.•SO4−, OH, and SO5− participate in the transformation and generation of singlet oxygen (1O2).•DFT calculation revealed that Mo sites on the bimetallic MoFe (110) facet are more favorable to adsorb PMS molecules.•Electrons transferring from the Mo to Fe atoms facilitated the adsorption of the negatively charged HSO5− anions. Sulfate-radical (SO4−) based Advanced Oxidation Process (SR-AOP), which is mainly generated from peroxymonosulfate (PMS) activation, is an excellent route for water treatment. Bimetallic nanoparticles have been widely applied in electronic, chemical, biological, and mechanical fields, etc.; however, few researchers have attempted to adopt bimetallic nanoparticles in environmental remediation. Further, in recent years, element molybdenum (Mo) has addressed much more environmental field attention than ever. Although singlet oxygen (1O2) generated commonly in SR-AOPs, its generation mechanism remains controversial. Hence, in this work, bimetallic MoFe/TiO2 nanospheres were rationally constructed via a facile two-step methodology. Undoubtedly, it exhibited superior performance for the degradation of organic pollutants (e.g., rhodamine, phenol, 4-chlorophenol and sulfadiazine) irradiated by simulated solar light. Both photo-generated electrons and transition metallic redox couples (i.e., Mo6+/Mo4+, Fe3+/Fe2+ and Mo4+/Fe3+) play vital roles in the PMS activation. Distinct from conventional SR-AOPs, sulfate radicals (SO4−), hydroxyl radicals (OH) and peroxymonosulfate radicals (SO5−) indeed participate in the transformation and generation of singlet oxygen (1O2). With the combination of DFT calculation, the Mo sites on the bimetallic MoFe (110) facet are more favorable to adsorb PMS molecules, then followed by the dissociation of PMS progressing on the Mo sites. Electrons transferring from the Mo atoms to the Fe atoms facilitated the adsorption of the negatively charged HSO5- anions, resulting in enhanced PMS activation efficiency. Considering its novelty and generation mechanism, this work highlights the mechanism of 1O2 generation from PMS reduction and oxidation simultaneously and furnishes theoretical support for further relevant studies.