Showing papers by "Changbin Zhang published in 2014"
TL;DR: The results showed that Na species addition can induce and further stabilize a negatively charged and well-dispersed Pd species, which then facilitates the activation of H2O and chemisorbed oxygen, therefore resulting in the high performance of the 2Na-Pd/TiO2 catalyst for the ambient HCHO destruction.
Abstract: Catalytic oxidation of formaldehyde (HCHO) to CO2 at ambient conditions is of great interest for indoor HCHO purification. Here, we report that sodium-doped Pd/TiO2 is a highly effective catalyst for the catalytic oxidation of HCHO at room temperature. It was observed that Na doping has a dramatic promotion effect on the Pd/TiO2 catalyst and that nearly 100% HCHO conversion could be achieved over the 2Na-Pd/TiO2 catalyst at a GHSV of 95000 h(-1) and HCHO inlet concentration of 140 ppm at 25 degrees C. The mechanism of the Na-promotion effect was investigated by using Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), CO chemisorption, Temperature-programmed reduction by H-2 (H-2-TPR), X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption of O-2 (O-2-TPD) methods. The results showed that Na species addition can induce and further stabilize a negatively charged and well-dispersed Pd species, which then facilitates the activation of H2O and chemisorbed oxygen, therefore resulting in the high performance of the 2Na-Pd/TiO2 catalyst for the ambient HCHO destruction.
240 citations
TL;DR: Experimental results indicated that Ag/CeO2 induced the production of intracellular ROS and disruption of the cell wall and cell membrane and a possible production mechanism of ROS and bactericidal mechanism of catalytic oxidation were proposed.
75 citations
TL;DR: In this article, a surface-fluorinated TiO2 (F-TiO2) catalyst was synthesized by a hydrothermal method using hydrofluoric acid (FIF) solution as a capping agent, and the as-prepared catalysts were tested for the photocatalytic oxidation (PCO) of gaseous NH3 under UV light.
Abstract: A surface-fluorinated TiO2 (F-TiO2) catalyst was synthesized by a hydrothermal method using hydrofluoric acid (FIF) solution as a capping agent, and defluorinated TiO2 (D-TiO2) was next obtained by washing the F-TiO2 with NaOH solution. The as-prepared catalysts were tested for the photocatalytic oxidation (PCO) of gaseous NH3 under UV light. The F-TiO2 catalyst exhibited remarkable activity for NH3 removal, about twice as high as that of the commercial catalyst P25. In contrast, D-TiO2 showed an obvious decrease in PCO activity. The catalysts were characterized by X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) adsorption analysis, High-resolution Transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS). The results showed that the surface fluorination process formed the surface equivalent to Ti-F group and also increased the percentage of reactive (0 0 1) facets to about 50%; the surface defluorination removed the fluorine (F) element from the F-TiO2 surface but showed no influence on the percentage of reactive (0 0 1) facets. By comparing the specific activities of the catalysts, we found that both the active (0 0 1) facets and the surface group contributed to the improvement of the PCO activity, while the surface equivalent to Ti-F group plays the dominant role. The equivalent to Ti-F group could retard the recombination of photogenerated electrons and holes, which is possibly the major reason for the excellent activity of the F-TiO2 catalyst. (c) 2014 Elsevier B.V. All rights reserved.
55 citations
TL;DR: The TiO2 sample calcined at 400°C contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light.
Abstract: Carbon-modified titanium dioxide (TiO2) was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation (PCO) of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400°C had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range (< 300°C). However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400°C contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light.
30 citations