A series
of Pd/TiO2 photocatalysts were synthesized
by a simple glucose reduction method, and their photocatalysis properties
were evaluated in an array of CO2 hydrogenations. The samples
were characterized by XRD, SEM, TEM, EDX, EDX mapping, UV–vis
DRS, Raman spectroscopy, PL spectroscopy, XPS, and N2 adsorption.
In terms of product yields (in micromoles per gram of catalyst), a
1.0 wt % Pd/TiO2 catalyst (CH4, 355.62; CO,
46.35; C2H6, 39.69) was found to be superior
to pristine TiO2 (CH4, 42.65; CO, 4.73; C2H6, 2.7) and other composites under UV irradiation
for 3 h, possibly because of a synergistic effect between the palladium
nanoparticles and the TiO2 support. The palladium nanoparticles
on the surface of TiO2 substantially accelerated electron
transfer and acted as active sites for the adsorption and activation
of CO2 molecules, to promote CO2 hydrogenation.
During the photocatalytic CO2 hydrogenation, dissociated
hydrogen reacts with CO2
– activated on
the Pd/TiO2 photocatalyst to form a new PdC surface
species that is stable during the reaction and further transforms
to generate methane. A detailed mechanism of photocatalytic CO2 hydrogenation is discussed to account for the performance
of the Pd/TiO2 photocatalyst in the reaction.
publicado na web em 01/06/2017 A novel rhodamine-based Hg 2+ chemosensor P2 containing polyether was readily synthesized and investigated, which displayed high selectivity and sensitivity for Hg 2+ . Because of good water-solubility of polyther, the rhodamine-based chemosensor containing polyether can be used in aqueous solution. The sensor responded rapidly to Hg 2+ in pure water solutions with a 1:1 stoichiometry. Meanwhile, it indicated excellent adaptability and also the responsiveness.
Six rhodamine-based “turn-on” fluorescence chemosensors (L1–L6) with different substituents for mercury (Hg2+) were readily synthesized and investigated; they displayed high selectivity and chelation enhanced ratiometric fluorescence change and colorimetric change with Hg2+ among the metal ions examined. Based on UV and fluorescence spectral data, the effects of different substituents on spectral properties of the probes were presented and discussed. The detection limit of Hg2+ to probe L1 was as low as 50 nmol/L because of its electron-donating group. Theoretical calculation also supported the process of reaction. Confocal laser scanning microscopy experiments showed that probe could be used to detect Hg2+ in living cells.
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