Catalytic Ozonation of Polluter Benzene from -20 to >50 °C with High Conversion Efficiency and Selectivity on Mullite YMn2O5.

Catalytic decomposition of aromatic polluters at room temperature represents a green route for air purification but is currently challenged by the difficulty of generating reactive oxygen species (ROS) on catalysts. Herein, we develop a mullite catalyst YMn2O5 (YMO) with dual active sites of Mn3+ and Mn4+ and use ozone to produce a highly reactive O* upon YMO. Such a strong oxidant species on YMO shows complete removal of benzene from -20 to >50 °C with a high COx selectivity (>90%) through the generated reactive species O* on the catalyst surface (60 000 mL g-1 h-1). Although the accumulation of water and intermediates gradually lowers the reaction rate after 8 h at 25 °C, a simple treatment by ozone purging or drying in the ambient environment regenerates the catalyst. Importantly, when the temperature increases to 50 °C, the catalytic performance remains 100% conversion without any degradation for 30 h. Experiments and theoretical calculations show that such a superior performance stems from the unique coordination environment, which ensures high generation of ROS and adsorption of aromatics. Mullite's catalytic ozonation degradation of total volatile organic compounds (TVOC) is applied in a home-developed air cleaner, resulting in high efficiency of benzene removal. This work provides insights into the design of catalysts to decompose highly stable organic polluters.

Charge-controlled switchable CO2 capture and gas separation using BC3 nanosheets.

The technique of CO2 capture and separation using charge-modulated sorbent materials holds promise for reducing CO2 emissions. Density functional theory with long-range dispersion correction has been used to study the adsorption of CO2, H2, CH4, and N2 on BC3 nanosheets with/without charge injections. We find that CO2 is weakly adsorbed on pristine BC3, but injection of 3 negative charges (3 e) can change the adsorption to chemical adsorption. Removing the charge results in the release of CO2 without any energy barrier. A high capacity of 4.30 × 1014 cm-2 can be achieved with 5 e charge injection, and CO2 molecules could automatically desorb after charge removal. Additionally, negatively charged BC3 exhibits high selectivity for separating CO2 from other industrial gases such as CH4, H2, and N2. Our findings provide useful guidance for the development of switchable CO2 capture and storage materials.

Direct Observation of ß-Barrel Intermediates in the Self-Assembly of Toxic SOD128-38 and Absence in Nontoxic Glycine Mutants.

Soluble low-molecular-weight oligomers formed during the early stage of amyloid aggregation are considered the major toxic species in amyloidosis. The structure-function relationship between oligomeric assemblies and the cytotoxicity in amyloid diseases are still elusive due to the heterogeneous and transient nature of these aggregation intermediates. To uncover the structural characteristics of toxic oligomeric intermediates, we compared the self-assembly dynamics and structures of SOD128-38, a cytotoxic fragment of the superoxide dismutase 1 (SOD1) associated with the amyotrophic lateral sclerosis, with its two nontoxic mutants G33V and G33W using molecular dynamics simulations. Single-point glycine substitutions in SOD128-38 have been reported to abolish the amyloid toxicity. Our simulation results showed that the toxic SOD128-38 and its nontoxic mutants followed different aggregation pathways featuring distinct aggregation intermediates. Specifically, wild-type SOD128-38 initially self-assembled into random-coil-rich oligomers, among which fibrillar aggregates composed of well-defined curved single-layer ß-sheets were nucleated via coil-to-sheet conversions and the formation of ß-barrels as intermediates. In contrast, the nontoxic G33V/G33W mutants readily assembled into small ß-sheet-rich oligomers and then coagulated with each other into cross-ß fibrils formed by two-layer ß-sheets without forming ß-barrels as the intermediates. The direct observation of ß-barrel oligomers during the assembly of toxic SOD128-38 fragments but not the nontoxic glycine-substitution mutants strongly supports ß-barrels as the toxic oligomers in amyloidosis, probably via interactions with the cell membrane and forming amyloid pores. With well-defined structures, the ß-barrel might serve as a novel therapeutic target against amyloid-related diseases.