An investigation of nanostructured rutile and anatase plates for improving the photosplitting of water

Abstract

Developing new semiconductor materials for improving photocatalytic reactivity is important for solving the challenging environmental and energy problems we are facing today. This work focuses on increasing the quantum efficiency in titania photocatalysts for photocatalytic (oxidation of acetaldehyde) and photosynthetic (photosplitting of water) reactions by synthesizing pure phase rutile and anatase nanostructures with well defined morphologies and investigating their photocatalytic performance compared to a commercial titania photocatalyst (Degussa P25). Nanostructured anatase is dominated by {100} surfaces with a small amount of {101} surfaces, whereas the rutile nanoplates consist of nanorods dominated by {110} and {111} crystal surfaces. In accordance with the signals from electron spin resonance (ESR) spectra, both nanostructured anatase and rutile phases have high photocatalytic activity for photosplitting of water compared to P25 titania. The anatase phase shows a high activity for photocatalytic oxidation (PCO) of acetaldehyde whereas the rutile phase shows a lower activity. The results of these experiments basically agree with previously published works that reported that the oxidation and reduction sites on rutile particles are on the {011} and {110} faces respectively, and on {001} and {011} faces respectively for anatase particles. The results have important implications for enhancing the photocatalytic activity of titania for environmental remediation, increasing the quantum efficiency in photo-voltaic (PV) solar cells and other photo-assisted processes.

Nanostructured Titanium Dioxide for Photocatalytic Water Treatment

“…The ratio B/A defines the degree of truncation. The shape predicted by the thermodynamic theory corresponds closely to that of anatase nanoparticles synthesized under nearequilibrium conditions by the sol-gel [84] or hydrothermal routes [85], as confirmed by the high-resolution transmission electron micrograph in figure 10.5. Simulated images of anatase nanocrystals [82,83] generated by the thermodynamic model and the standard Wulff construction are contrasted in figure 10.4; only the Ti atoms are shown for clarity and to facilitate comparison with transmission electron micrographs.…”

Photocatalytic Degradation of Mecoprop and Clopyralid in Aqueous Suspensions of Nanostructured N-doped TiO2

“…It can be observed that the synthesized TiO 2 powder consists of pure anatase (curve 1). The pattern of TiO 2 Degussa P25 powder (curve 3) exhibited both anatase and rutile crystalline polymorphs in a wt % ratio A: R = 88: 12 (Table 1), which is in accordance with recently reported values in the literature [14,15]. After the doping procedure, the crystalline structure of each powder was preserved (curves 2 and 4) due to the temperature of thermal treatment which was only 50 °C higher than the calcination temperature of the undoped powder and below the temperature of anatase-to-rutile phase transition.…”

Preparation of TiO2, Ag-doped TiO2 nanoparticle and TiO2–SBA-15 nanocomposites using simple aqueous solution-based chemical method and study of their photocatalytical activity

“…Zhang et al [26] and Anpo et al [27] have discussed about the mechanism responsible for photocatalytic activity of TiO 2 . Other than electronic and structural requirements, a number of factors such as size, morphology and surface area play a critical role in the photocatalytic efficiencies of TiO 2 [28]. Enhancement of surface area of the materials can improve the catalytic efficiency; so, it is important to develop a synthesis method for the preparation of catalysts composed of active TiO 2 species within high surface area matrix, such as porous alumina and silica.…”