A review on TiO2−x-based materials for photocatalytic CO2 reduction

Photocatalytic CO2 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 (TiO2) has been continuously modified and tailored for more desirable application. Recently, the defective/reduced titanium dioxide (TiO2-x) catalyst has attracted broad attention due to its excellent photocatalytic performance for CO2 reduction. In this perspective review, we comprehensively present the recent progress in TiO2-x-based materials for photocatalytic CO2 reduction. In detail, the review starts with the fundamentals of CO2 photocatalytic reduction. Then, the synthesis of a defective TiO2 structure is introduced for the regulation of its photocatalytic performance, especially its optical properties and dissociative adsorption properties. In addition, the current application of TiO2-x-based photocatalysts for CO2 reduction is also highlighted, such as metal-TiO2-x, oxide-TiO2-x and TiO2-x-carbon-based photocatalysts. Finally, the existing challenges and possible scope of photocatalytic CO2 reduction over TiO2-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 TiO2-x.