Insights into Different Photocatalytic Oxidation Activities of Anatase, Brookite, and Rutile Single-Crystal Facets

Abstract

For the understanding of the activity of TiO2 photocatalysts, knowledge of the activities of different crystal facets is necessary. This information can be achieved by the investigation of well-defined single-crystalline TiO2 surfaces. In this study, the photocatalytic activity of different anatase, brookite, and rutile single-crystal wafers with only one exposed surface has been investigated via the oxidation of methanol and the hydroxylation of terephthalic acid, respectively. X-ray diffraction, atomic force microscopy, and scanning electron microscopy measurements have shown that all surfaces are clearly defined and possess a smooth surface, which allows a reliable comparison of the photocatalytic activities. The investigated anatase surfaces show higher activity than the rutile surfaces, while the brookite surface is interestingly the least active one. To the best of our knowledge, there are no other reports based on the investigation and comparison of well-defined TiO2 anatase (100), anatase (001), and brookite (100) single-crystalline surfaces concerning their photocatalytic activity. Furthermore, the influence of the coordination of the superficial titanium and the oxygen ions on the photocatalytic activity is discussed.

Tailoring the Photoelectrochemical Activity of TiO2 Electrodes by Multilayer Screen‐Printing

“…Fujishima and Honda described in 1972 the photoelectrochemical splitting of water over TiO 2 electrodes . Since then, many studies have investigated the photocatalytic properties of TiO 2 , not only in powdered form but also as single crystals and films . The application of such materials goes beyond photocatalysis, finding use as gas sensors, in solar cells, or as biomedical coatings …”

Quantitative Analysis of Anatase‐Rutile Mixtures by Raman Spectroscopy

“…Meanwhile, catalytic performance of TiO 2 ‐based catalysts has been correlated with the percentage of a particular TiO 2 phase. Anatase‐rich titanium dioxide is more active comparative to rutile and brookite for the oxidation of methanol . High ethylene selectivity in selective acetylene hydrogenation was achieved over TiO 2 samples with 0–44 % rutile phase .…”

“…Anatase-rich titanium dioxide is more active comparative to rutile and brookite for the oxidation of methanol. [5] High ethylene selectivity in selective acetylene hydrogenation was achieved over TiO 2 samples with 0-44 % rutile phase. [6] Therefore the accurate calculation of the fraction of different phases in the titanium dioxide mixture is important in developing the structure-activity relationship for catalysis applications.…”

TiO2 superstructures with oriented nanospaces: a strategy for efficient and selective photocatalysis

“…[24][25][26][27] Photocatalytic activity of metal oxides is highly dependent on the exposed crystal facets in addition to their specific surface area, composition, and crystal size. [28][29][30][31] The crystal-face dependences of adsorption affinity and reactivity have been studied on TiO2 nanocrystals, microcrystals, and mesocrystals systematically by changing the ratio of the exposed crystal facets. [32][33][34][35] It is nowadays widely accepted that the {001} and {101} facets of anatase TiO2 are more favorable for oxidation and reduction reactions, respectively.…”