The oxygen vacancy in MnO2 is normally proved as the reactive site for the catalytic ozonation, and acquiring a highly reactive crystal facet with abundant oxygen vacancy by facet engineering is advisable for boosting the catalytic activity. In this study, three facet-engineered α-MnO2 was prepared and successfully utilized for catalytic ozonation toward an odorous CH3SH. The as-synthesized 310-MnO2 exhibited superior activity in catalytic ozonation of CH3SH than that of 110-MnO2 and 100-MnO2, which could achieve 100% removal efficiency for 70 ppm of CH3SH within 20 min. The results of XPS, Raman, H2-TPR, and DFT calculation all prove that the (310) facets possess a higher surface energy than other facets can feature the construction of oxygen vacancies, thus facilitating the adsorption and activate O3 into intermediate peroxide species (O2–/O2 2–) and reactive oxygen species (•O2 –/1O2) for eliminating adjacent CH3SH. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) revealed that the CH3SH molecular was chemisorbed on S atom to form CH3S–, which was further converted into intermediate CH3SO3 – and finally oxidized into SO4 2– and CO3 2–/CO2 during the process. Attributed to the deep oxidation of CH3SH on 310-MnO2 via efficient cycling of active oxygen vacancies, the lifetime of 310-MnO2 can be extended to 2.5 h with limited loss of activity, while 110-MnO2 and 100-MnO2 were inactivated within 1 h. This study deepens the comprehension of facet-engineering in MnO2 and presents an efficient and portable catalyst to control odorous pollution.

In this study, Ag deposited three-dimensional MnO 2 porous hollow microspheres (Ag/MnO 2 PHMSs) with high dispersion of the atom level Ag species are first prepared by a novel method of redox precipitation. Due to the highly efficient utilization of downsized Ag nanoparticles, the optimal 0.3% Ag/MnO 2 PHMSs can completely degrade 70 ppm CH 3 SH within 600 s, much higher than that of MnO 2 PHMSs (79%). Additionally, the catalyst retains longterm stability and can be regenerated to its initial activity through regeneration with ethanol and HCl. The results of characterization of Ag/MnO 2 PHMSs and catalytic performance tests clearly demonstrate that the proper amount of Ag incorporation not only facilitates the chemi-adsorption but also induces more formation of vacancy oxygen (O v ) and lattice oxygen (O L ) in MnO 2 as well as Ag species as activation sites to collectively favor the catalytic ozonation of CH 3 SH. Ag/MnO 2 PHMSs can efficiently transform CH 3 SH into CH 3 SAg/CH 3 S-SCH 3 and then oxidize them into SO 4 2− and CO 2 as evidenced by in situ diffuse reflectance infrared Fourier transform spectroscopy. Meanwhile, electron paramagnetic resonance and scavenger tests indicate that •OH and 1 O 2 are the primary reactive species rather than surface atomic oxygen species contributing to CH 3 SH removal over Ag/MnO 2 PHMSs. This work presents an efficient catalyst of single atom Ag incorporated MnO 2 PHMSs to control air pollution.

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A self-stabilized Z-scheme porous g-CN/I-containing BiOI ultrathin nanosheets (g-CN/I-BiOI) heterojunction photocatalyst with I/I redox mediator was successfully synthesized by a facile solvothermal method coupling with light illumination. The structure and optical properties of g-CN/I-BiOI composites were systematically characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, N adsorption/desorption, UV-vis diffuse reflectance spectrum, and photoluminescence. The g-CN/I-BiOI composites, with a heterojunction between porous g-CN and BiOI ultrathin nanosheets, were first applied for the photocatalytic elimination of ppm-leveled CHSH under light-emitting diode visible light illumination. The g-CN/I-BiOI heterojunction with 10% g-CN showed a dramatically enhanced photocatalytic activity in the removal of CHSH compared with pure BiOI and g-CN due to its effective interfacial charge transfer and separation. The adsorption and photocatalytic oxidation of CHSH over g-CN/I-BiOI were deeply explored by in situ diffuse reflectance infrared Fourier transform spectroscopy, and the intermediates and conversion pathways were elucidated and compared. Furthermore, on the basis of reactive species trapping, electron spin resonance and Mott-Schottky experiments, it was revealed that the responsible reactive species for catalytic CHSH composition were h, O, and O; thus, the g-CN/I-BiOI heterojunction followed an indirect all-solid state Z-scheme charge-transfer mode with self-stabilized I/I pairs as redox mediator, which could accelerate the separation of photogenerated charge and enhance the redox reaction power of charged carriers simultaneously.