As an important metal oxide, anatase titanium dioxide has been widely investigated because of its many promising properties in catalysis and photocatalysis. The properties of anatase TiO 2 crystals are largely determined by external surfaces exposed. Many efforts have been made to improve the percentage of high-reactive facets like {001} facets of anatase TiO 2 to enhance its catalytic properties. This review reports the recent progress in designing and fabricating high-reactive facets dominated anatase TiO 2 via various strategies including traditional vapor phase epitaxial processes, hydrothermal/solvothermal methods, nonhydrolytic alcoholysis methods and high temperature gas phase reactions. Furthermore, focusing on (001) surface, the review also covers advances in the theoretic simulations of various high-reactive facets of anatase TiO 2 crystals. Finally, we offer a summary and some perspectives on the challenges and new directions for future research in this emerging frontier. 1. Introduction Metallic and semiconducting nanocrystals with tailored facets have always attracted intense interests in the last decade due to their many intrinsic shape-dependent properties, such as water splitting for hydrogen, solar cells, CO 2 reduction, gas sensors etc. 1-21 As one of the commonly available and most studied metal oxides, titanium dioxide (TiO 2) has been widely used as a pigment and in sunscreens, paints, ointments, toothpaste, and catalysis. 9 we have witnessed an exponential growth of research activities since Fujishima and Honda discovered the phenomenon of photocatalytic splitting of water on a TiO 2 electrode under ultraviolet (UV) light in1972. 22 Many promising applications have been developed
Uniform anatase TiO(2) particles exposed by {001} facets were successfully synthesized by using EDTA together with F as morphology controlling agents. The crystallographic structure as well as the growth mechanism of anatase TiO(2) particles was investigated systematically by XRD, SEM, TEM and XPS, respectively.
A new synthetic strategy was developed to prepare large-sized well-defined anatase TiO(2) nanosheets wholly dominated with thermodynamically unfavorable high-reactive {001} and {100} facets, which has a percentage of 98.7% and 1.3%, respectively. The as-prepared anatase TiO(2) nanosheets show a well-faceted morphology and have a large size in length (ca. 4.14 μm). The formation mechanism of the anatase TiO(2) nanosheets was also analyzed and investigated.
Solar hydrogen production assisted with semiconductor materials is a promising way to provide alternative energy sources in the future. Such a photocatalytic reaction normally takes place on the active sites of the catalysts surface, and the identification of the active sites is crucial for understanding the photocatalytic reaction mechanism and further improving the photocatalytic efficiency. However, the active sites of model catalysts are still largely disputed because of their structural complexity. Conventionally, H 2 evolution from solar water splitting over Pt/TiO 2 is widely deemed to take place on metallic Pt nanoparticles. Oppositely, we report through a combined experimental and theoretical approach, that metallic Pt nanoparticles have little contribution to the activity of photocatalytic H 2 evolution; the oxidized Pt species embedded on the TiO 2 surface are the key active sites and primarily responsible for the activity of the hydrogen evolution Pt/TiO 2 photocatalyst.
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