Papers by Keyword: Nanocatalysts

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Authors: Randi Dangerfield, Shannon Sharp, Rui Gang Wang
Abstract: We report a facile hydrothermal synthesis in base solution for shape/size-controlled ceria (CeO2) nanocrystals and CeO2-ZrO2 solid solution. CeO2 nanocrystals in the shape of nanorods, nanotubes, or nanocubes with reactive {110} and {200} faces can be produced using this hydrothermal method. We found that hydrothermal reaction temperature is a critical parameter to control the shape and size of ceria nanocrystals. Above 210 °C, high resolution transmission electron microscopy studies revealed that the CeO2 nanocubes expose predominant {200} crystal planes. Microscopic investigation showed that the CeO2-ZrO2 solid solutions synthesized using this method had high crystallinity, and compositional homogeneity, and improved low-temperature reducibility.
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Authors: Rui Gang Wang, Varun Sama, Ding Qiang Li, Samuel I. Mutinda
Abstract: Three rare-earth metal oxide nanopowders (CeO2, PrO2, and TbO2) were synthesized using a facile hydrothermal method in a Teflon-lined autoclave. The rare-earth metal oxide nanocrystals with variable morphology were prepared by controlling the synthesis conditions with temperatures in the range of 70−220 °C. X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and temperature programmed reduction (TPR) were used to characterize the average structures and redox properties of these materials. Transmission electron microscopy (TEM) was used to investigate the morphology, particle size, and formation and growth mechanisms of the rare-earth metal oxide nanoparticles in solution-based environment.
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Authors: Ling Bin Kong, Ru Tao Wang, Xiao Wei Wang, Zhen Sheng Yang, Yong Chun Luo, Long Kang
Abstract: Metal nanocatalysts, as the anodic materials, have become increasingly important in fuel cells due to their unique physical and chemical properties. Here we report the ordered mesoporous carbon (CMK-3) supported silver nanocatalysts have been prepared through the wet chemical reduction by using the reduction of formaldehyde. The electrochemical properties of the Ag/CMK-3 nanocatalysts for formaldehyde oxidation are studied by cyclic voltammograms (CV) and chronoamperometric curves (i-t) in alkaline aqueous solutions. The results show that the peak current density (from CV) of the Ag/CMK-3 electrode is 112 mA cm-2, above 2 times higher than that of Ag/XC-72 at the same Ag loading (14.15 μg cm-2). Furthermore, the i-t curves demonstrate that the Ag/CMK-3 nanocatalysts are efficient and stable electrocatalysts for anodic oxidation of formaldehyde in alkaline solutions. Our results indicate that the application potential of Ag/CMK-3 nanocatalysts with the improved electrocatalytic activity has far reaching effects on fuel cells and sensors.
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Authors: Iqra Muneer, Muhammad Akhyar Farrukh, Shaghraf Shaghraf, Muhammad Khaleeq-Ur-Rahman, Akrajas Ali Umar, Rohana Adnan
Abstract: Solvent controlled synthesis of tin oxide nanocatalysts were prepared via the hydrothermal method. To study the effect of solvent on the particle size of tin oxide and their catalytic efficiency on photodegradation of environmental hazardous materials, the synthesis was carried out at different concentrations of solvent (isoamyl alcohol) keeping all other reaction conditions constant. The nanoparticles were characterized by FourierTransmission Infrared Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray Diffraction and Thermogravimetric analysis. Prepared nanoparticles were applied as nanocatalyst under UV-visible light for the photodegradation of methyl green,which is an abundant organic pollutant of industrial waste water. Photodegradation activities of the nanocatalysts were measured in three different ways, i. pseudo first order rate constant, “k”. ii. percentage degradationand iii. degradation rate. Effect of solvent was quantitatively explained in term of double sphere model of ion-ion interaction. Degradation of pollutants was also monitored by High Performance Liquid Chromatography.
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