Facial controlled synthesis of Pt/MnO2 catalysts with high efficiency for VOCs combustion.

Two sets of experiments were initially implemented to explore the best impregnation method and the best morphology substrate. In the first case, Pt/MnO2-r-WI catalyst showed a better performance than that of Pt/MnO2-r-IW. The test results illustrated that Wetness Impregnation (WI) could enhance the dispersion of Pt, ratios of Mn4+/Mn3+, Oads/Olatt and Pt4+/Pt0 as compared to those of Incipient Wetness Impregnation (IW). In the other method, MnO2-s catalyst displayed a higher catalytic efficiency than that of MnO2-r because the nanosphere morphology had larger BET surface area and pore volume to attract Pt atoms and toluene molecules. Therefore, the Pt/MnO2-s-WI catalyst was obtained and showed the best activity with low-temperature redox capability and oxygen mobility. It could eliminate toluene (T 90) at a low temperature of 205 °C and remain stable over 150 h. effects of calcination temperature, toluene concentration and gas hourly space velocity (GHSV) were also investigated herein. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was also implemented to explore the reaction mechanism. It demonstrated that toluene was firstly adsorbed over Pt δ+ on the surface before being oxidized to CO2 and H2O. The whole procedure follows the Mars-van Krevelen mechanism. This work gives a comprehensive understanding of the heterogeneous catalysis mechanism.

A Temperature-Sensitive Luminescent Ag42 Nanocluster Supported by TertButyl Thiol Ligands.

Compound [Ag42 S5 (StBu)25 (CF3 COO)4 (CO3 )](CO3 )0.5 ⋅CH2 Cl2 ⋅4CH3 OH⋅9DMF (1) has been obtained and well defined. It consists of a multi-shell structure involving two Ag centres, one Ag5 S5 pentagram, two Ag5 S5 pentagons and one Ag25 S15 shell. Compound 1 has been characterized by XPS, FT-IR, PXRD, TGA, NMR, MS, UV/Vis spectrum, TEM and cyclic voltammetry. Temperature-sensitive luminescent property of 1 has also been investigated.