Semiconductor photocatalysis has received much attention as a potential solution to the worldwide energy shortage and for counteracting environmental degradation. This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials. We begin with a survey of efforts to explore suitable materials and to optimize their energy band configurations for specific applications. We then examine the design and fabrication of advanced photocatalytic materials in the framework of nanotechnology. Many of the most recent advances in photocatalysis have been realized by selective control of the morphology of nanomaterials or by utilizing the collective properties of nano-assembly systems. Finally, we discuss the current theoretical understanding of key aspects of photocatalytic materials. This review also highlights crucial issues that should be addressed in future research activities.

In this study, for the first time, {111} facet exposed anatase TiO2 single crystals are prepared via both F– and ammonia as the capping reagents. In comparison with the most investigated {001}, {010}, and {101} facets for anatase TiO2, the density functional theory (DFT) calculations predict that {111} facet owns a much higher surface energy of 1.61 J/m2, which is partially attributed to the large percentage of undercoordinated Ti atoms and O atoms existed on the {111} surface. These undercoordinated atoms can act as active sites in the photoreaction. Experimentally, it is revealed that this material exhibits the superior electronic band structure which can produce more reductive electrons in the photocatalytic reaction than those of the TiO2 samples exposed with majority {010}, {101}, and {001} facets. More importantly, we demonstrate that this material is an excellent photocatalyst with much higher photocatalytic activity (405.2 μmol h–1), about 5, 9, and 13 times that of the TiO2 sample exposed with dominant {010}, {101}, and {001} facets, respectively. Both the superior surface atomic structure and electronic band structure significantly contribute to the enhanced photocatalytic activity. This work exemplifies that the surface engineering of semiconductors is one of the most effective strategies to achieve advanced and excellent performance over photofunctional materials for solar energy conversion.

A strategy of reaction-environment modulation was employed to change the surface property of a semiconductor photocatalyst to enhance its photocatalytic performance. Surface alkalinization induced by a high alkalinity of the solution environment significantly shifted the surface energy band of a SrTiO(3) photocatalyst to a more negative level, supplying a strong potential for H(2)O reduction and consequently promoting the photocatalytic efficiency of H(2) evolution. This mechanism is also applicable for visible-light-sensitive La,Cr-codoped SrTiO(3) photocatalyst, which hence, could achieve a high apparent quantum efficiency of 25.6% for H(2) evolution in CH(3)OH aqueous solution containing 5 M NaOH at an incident wavelength of 425 ± 12 nm.

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