A review on TiO 2- x -based materials for photocatalytic CO 2 reduction.

Photocatalytic CO 2 reduction technology has a broad potential for dealing with the issues of energy shortage and global warming. As a widely studied material used in the photocatalytic process, titanium dioxide (TiO 2 ) has been continuously modified and tailored for more desirable application. Recently, the defective/reduced titanium dioxide (TiO 2- x ) catalyst has attracted broad attention due to its excellent photocatalytic performance for CO 2 reduction. In this perspective review, we comprehensively present the recent progress in TiO 2- x -based materials for photocatalytic CO 2 reduction. In detail, the review starts with the fundamentals of CO 2 photocatalytic reduction. Then, the synthesis of a defective TiO 2 structure is introduced for the regulation of its photocatalytic performance, especially its optical properties and dissociative adsorption properties. In addition, the current application of TiO 2- x -based photocatalysts for CO 2 reduction is also highlighted, such as metal-TiO 2- x , oxide-TiO 2- x and TiO 2- x -carbon-based photocatalysts. Finally, the existing challenges and possible scope of photocatalytic CO 2 reduction over TiO 2- x -based materials are discussed. We hope that this review can provide an effective reference for the development of more efficient and reasonable photocatalysts based on TiO 2- x .