Supported metal catalysts have been used extensively in many current industrial processes. The morphology of coated metal on a support is usually an important factor affecting the efficiency of the catalyst. In this study, the investigation is focused on a photocatalytic process to coat silver clusters on titania (P-25 TiO2) with an emphasis on the morphology control of coated silver clusters. For the first time, the particle size and the deployment intervals of silver clusters are controlled with an innovative method that involves the in-situ formation of water-insoluble transitory species such as AgBr, AgCl, or Ag2O on the surface of titanium dioxide. Experimental results demonstrated that the transitory particles function as physical spacers, which temporarily occupy some of the active site on the titanium dioxide surface and act as reservoirs for Ag+ ions to keep the local Ag+ concentration on TiO2 extremely low. The silver clusters coated on titania are found to be stable in the spherical silver-3c syn crystalline form indicated by TEM, XRD, and XPS measurements.

tal particles coated on support has been proven to affect the performance of catalysts greatly. In this study, a simple photodeposition process will be introduced to coat palladium onto titanium dioxide with an emphasis on the morphology control and size distribution of palladium particles. The effect of pH on the morphology of palladium particles was systemically investigated. It is found that the deposited palladium particles can be controlled to have narrow particle size distribution and homogeneous dispersion by a simple pH-controlled process during photodeposition. Experimental results demonstrate that the adsorption competition between OH− and PdCl42− or it’s hydrolytic anions can efficiently keep local concentration of palladium ions on titanium dioxide extremely low to control the morphology of deposited palladium particles on titania. The as-prepared Pd/TiO2 particles are found to be crystallitic stable indicated by TEM, XRD and XPS measurements.

Solid-supported metal catalysts have been widely used in industrial processes. The morphology of coated metal on the support is usually an important factor affecting the efficiency of the catalyst. In this study, a photocatalytic process is utilized to control the morphology of platinum particles deposited on titania (Degussa P-25). More specifically, the effect of pH on the morphology and the valence state of platinum nanoparticles was systemically investigated. It is found that, via a simple pH-controlled process, various states of platinum (Pt0, PtIIO, or PtIVO2) can be deposited onto the support directly at will. In this paper, the mechanism of morphology control and the key influencing factors at different pH regimes will be discussed. Followed by photodeposition, a H2 thermal treatment process was employed to convert the oxides into metal platinum with narrow size distribution and even coverage on the supporting titania. Various techniques such as transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive analysis of X-rays, and X-ray photoelectron spectroscopy were employed to characterize the prepared titania-supported platinum particles.

Ag/TiO2 catalyst with fine size and homogeneous dispersion of coated silver clusters was synthesized by a recently developed pHcontrolled photocatalytic process and applied to the photocatalytic reduction of nitrate as an environmentally friendly and low-cost catalyst with formic acid as a hole scavenger. Compared with conventional preparation routes, the as-prepared Ag/TiO2 catalyst in this study shows better catalytic performance: a nitrate conversion of 98% and selectivity for nitrogen of ca. 100%, which can be achieved after 30 min of irradiation. The average activity was calculated to be ca. 24 mmolNO3− g−1 Ag min−1, which is much higher than that of most of Pd–Cubased nitrate hydrogenation systems in terms of metal usage, demonstrating its application potential. A similar photocatalytic efficiency and selectivity for nitrogen were also observed for nitrite photocatalytic reduction on this catalyst. The effects of Ag content, hole scavengers, concentration of formic acid, and other anions present in drinking water, such as SO4 2−, CO3 2−, and HCO3−, were systematically investigated.

A simple and green in situ hydrothermal method, free of organic templates or zeolite seeds, was examined and introduced by depositing several typical microporous aluminosilicate zeolites (Linde A, Linde Y, mordenite and ZSM-5) on cordierite supports. Such preparative factors as crystallization time, crystallization temperature and basic strength were systematically investigated to discuss their effect on the growth of zeolites on cordierite supports. The as-prepared zeolite/cordierite samples were characterized by various techniques and a supposed in situ growth mechanism of zeolites on supports was given. The aluminium atoms on cordierite supports were activated by OH- and these activated atoms subsequently built a zeolite framework together with the silicon atoms and aluminium atoms of the synthesis gel. Based on this, the in situ deposition of zeolites can be easily extended to other aluminium-containing supports.With respect to pure zeolite powders, the in situ coated zeolites on supports exhibited much better stability and accessibility, which were thought essential for industrial applications. Copper ion-exchanged ZSM-5/cordierite was studied as catalyst for the direct decomposition of NO and selective catalytic reduction of NO by propane in excess oxygen. Cu-ZSM-5/cordierite was found to exhibit an obviously enhanced turnover frequency compared to Cu-ZSM-5 powders, which made it a potential deNOx catalyst for future applications.