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Sulfate-radical (SO4[rad]−) 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[rad]−), hydroxyl radicals ([rad]OH) and peroxymonosulfate radicals (SO5[rad]−) 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. © 2021 Elsevier B.V.

Sulfate-radical (SO4[rad]−) 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[rad]−), hydroxyl radicals ([rad]OH) and peroxymonosulfate radicals (SO5[rad]−) 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. © 2021 Elsevier B.V.

Sulfate-radical (SO4[rad]−) 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[rad]−), hydroxyl radicals ([rad]OH) and peroxymonosulfate radicals (SO5[rad]−) 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. © 2021 Elsevier B.V.

Advanced oxidation processes (AOPs) based on sulfate radicals (SO4⋅-) suffer from low conversion rate of Fe(III) to Fe(II) and produce a large amount of iron sludge as waste. Herein, we show that by using MoO2 as a cocatalyst, the rate of Fe(III)/Fe(II) cycling in PMS system accelerated significantly, with a reaction rate constant 50 times that of PMS/Fe(II) system. Our results showed outstanding removal efficiency (96%) of L-RhB in 10 min with extremely low concentration of Fe(II) (0.036 mM), outperforming most reported SO4⋅--based AOPs systems. Surface chemical analysis combined with density functional theory (DFT) calculation demonstrated that both Fe(III)/Fe(II) cycling and PMS activation occurred on the (110) crystal plane of MoO2, whereas the exposed active sites of Mo(IV) on MoO2 surface were responsible for accelerating PMS activation. Considering its performance, and non-toxicity, using MoO2 as a cocatalyst is a promising technique for large-scale practical environmental remediation.

Advanced oxidation processes (AOPs) based on sulfate radicals (SO4⋅-) suffer from low conversion rate of Fe(III) to Fe(II) and produce a large amount of iron sludge as waste. Herein, we show that by using MoO2 as a cocatalyst, the rate of Fe(III)/Fe(II) cycling in PMS system accelerated significantly, with a reaction rate constant 50 times that of PMS/Fe(II) system. Our results showed outstanding removal efficiency (96%) of L-RhB in 10 min with extremely low concentration of Fe(II) (0.036 mM), outperforming most reported SO4⋅--based AOPs systems. Surface chemical analysis combined with density functional theory (DFT) calculation demonstrated that both Fe(III)/Fe(II) cycling and PMS activation occurred on the (110) crystal plane of MoO2, whereas the exposed active sites of Mo(IV) on MoO2 surface were responsible for accelerating PMS activation. Considering its performance, and non-toxicity, using MoO2 as a cocatalyst is a promising technique for large-scale practical environmental remediation.