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MnO 2 nanotubes loaded with Pt and Ni−Fe spinel were synthesized using simple hydrothermal and sol−gel techniques. After loading with Ni−Fe spinel, the specific surface area of the material increases 3-fold. This change helped to provide more active sites and facilitated the association between the catalyst and volatile organic compounds (VOCs). X-ray photoelectron spectroscopy determined that the adsorbed oxygen concentrations were all greatly increased after Pt loading, indicating that Pt promoted the adsorption of oxygen and so accelerated the combustion process. The performance of the catalyst after loading with 2 wt % Pt was greatly improved, such that the T 90 for benzene decomposition was decreased to 113 °C. In addition, the 2% Pt/2Mn@NFO exhibited excellent low-temperature catalytic activity when reacting with low concentrations of toluene and ethyl acetate. This work therefore demonstrates a viable new approach to the development of Mn-based catalysts for the low temperature catalytic remediation of VOCs.

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A series of porous Pt/Fe x Ce y microflowers have been synthesized through a solvothermal method. The well-defined mesoporous structure promotes gas distribution as well as even dispersion of active species, thus exposing more active sites and improving the catalytic efficiency for low-temperature toluene removal. The catalyst composition can be regulated by changing the Fe/Ce molar ratio and Pt loading content. Among the samples, 1 wt % Pt/Fe3Ce1 performed the best, with a reaction temperature for 90% toluene conversion of 192 °C at a WHSV of 36,000 mL/(h·g). The synergistic effect of Fe2O3 and CeO2 promotes electron transfer and migration of oxygen species. Addition of Pt enhances the mobility of lattice oxygen, generating a high concentration of active surface lattice oxygen, which facilitates toluene removal. The Mars–van Krevelen model could be applied to explain the mechanism of toluene oxidation over these Fe-based catalysts.

Nitrogen doping can enhance the catalytic activity of carbon materials for activating peroxymonosulfate (PMS). The structure of nitrogen may strongly influence the generation of reactive oxygen species (ROS). However, few studies have focused on the methods for measuring ROS concentrations, making it difficult to assess the role of nitrogen species in PMS activation. Herein, we synthesized a series of nitrogen-doped waste-tire carbon and established a kinetic model with probes to estimate the ROS concentrations. Waste-tire carbon was doped with nitrogen via vibration milling and calcination, which generated the structures of graphitic N and pyridinic N. Both radical (•OH, SO4 •–) and nonradical (1O2) species were discovered by electron paramagnetic resonance. The calculations with the kinetic model revealed that 1O2 was the main ROS. Besides, combined with the density functional theory, graphitic N was suggested to be responsible for the generation of 1O2. This work provides a green catalyst developed from solid waste and an effective protocol to monitor the ratios of ROS in the degradation of pollutants with PMS.