Self-quenching in the aggregation state is overcome, and tunable solid-state photoluminescence of carbon-dot powder is achieved. Furthermore, based on the controllable optical property in organic solvents, a novel concept, i.e., constructing dual-fluorescence morphologies from single luminescent species, is presented to realize white-light emission.

Anatase TiO 2 -supported manganese and cobalt oxide catalysts with different Co/Mn molar ratios were synthesized by a conventional impregnation method and used for selective catalytic reduction (SCR) of NO x with NH 3 . The catalysts were characterized by N 2 adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed desorption with NH 3 and NO x . Characterization of the catalyst confirmed that by using Co 3 O 4 over Mn/TiO 2 , we enhanced NO oxidation ability. From in situ diffuse reflectance infrared transform spectroscopy (DRIFTs) analysis of desorption and the transient reaction, we concluded that the addition of Co could remarkably lower the activation energy of NO x chemisorption on the catalyst surface. In addition, low-temperature SCR activity mainly results from a "fast SCR" reaction. We observed four NO x species (bidentate nitrates, gaseous NO 2 , linear nitrites, and monodentate nitrites) on the surface of Mn/TiO 2 and Co−Mn/TiO 2 catalysts that all participated in the SCR reaction in the high temperature range. Doping of cobalt greatly improved the reactivity of gaseous NO 2 , linear nitrites, and monodentate nitrites, which makes Co−Mn/TiO 2 a highly effective NH 3 −SCR catalyst.

No abstract

No abstract

The Co 3 O 4 and Mn-doped Co 3 O 4 nanoparticle were synthesized by a co-precipitation method and used as selective catalytic reduction of NO with NH 3 (NH 3 -SCR) catalysts. After the doping of manganese oxides, the NH 3 -SCR activity of Mn 0.05 Co 0.95 O x catalyst is greatly enhanced. The NO oxidation ability of two catalysts is compared, and the X-ray diffraction results demonstrate that Mn has been successfully doped into the lattice of Co 3 O 4 . The X-ray photoelectron spectroscopy and temperature-programmed reduction with H 2 results confirmed that there is a strong interaction between Mn and Co in the Mn 0.05 Co 0.95 O x catalyst. Their adsorption and desorption properties were characterized by temperature-programmed desorption with NH 3 or NO + O 2 and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTs). These results indicated that the doping of manganese could provide more acid sites on the catalysts, and bidentate nitrates species originated from NO x adsorption are obviously activated on the Mn 0.05 Co 0.95 O x catalyst surface. Moreover, the transient reaction studied by in situ DRIFTs found that the "fast SCR" reaction participated by gaseous NO 2 and the standard SCR reaction participated by bidentate nitrates contribute to the low-temperature SCR activity.