Photocatalytic conversion of CO2 to useful products is an alluring approach for acquiring the two-fold benefits of normalizing excess atmospheric CO2 levels and the production of solar chemicals/fuels. Therefore, photocatalytic materials are continuously being developed with enhanced performance in accordance with their respective domains. In recent years, nanostructured photocatalysts such as one dimensional (1-D), two dimensional (2-D) and three dimensional (3-D)/hierarchical have been a subject of great importance because of their explicit advantages over 0-D photocatalysts, including high surface areas, effective charge separation, directional charge transport, and light trapping/scattering effects. Furthermore, the strategy of doping (metals and non-metals), as well as coupling with a secondary material (noble metals, another semiconductor material, graphene, etc.), of nanostructured photocatalysts has resulted in an amplified photocatalytic performance. In the present review article, various titanium dioxide (TiO2)-based nanostructured photocatalysts are briefly overviewed with respect to their application in photocatalytic CO2 conversion to value-added chemicals. This review primarily focuses on the latest developments in TiO2-based nanostructures, specifically 1-D (TiO2 nanotubes, nanorods, nanowires, nanobelts etc.) and 2-D (TiO2 nanosheets, nanolayers), and the reaction conditions and analysis of key parameters and their role in the up-grading and augmentation of photocatalytic performance. Moreover, TiO2-based 3-D and/or hierarchical nanostructures for CO2 conversions are also briefly scrutinized, as they exhibit excellent performance based on the special nanostructure framework, and can be an exemplary photocatalyst architecture demonstrating an admirable performance in the near future.
Keywords: 1-D nanostructures; 2-D nanostructures; TiO2; hierarchical nanostructures; photocatalytic CO2 conversion; reactions mechanism.