Review of material design and reactor engineering on TiO2 photocatalysis for CO2 reduction

Abstract

The continuous combustion of non-renewable fossil fuels and depletion of existing resources is intensifying the research and development of alternative future energy options that can directly abate and process ever-increasing carbon dioxide (CO 2 ) emissions. Since CO 2 is a thermodynamically stable compound, its reduction must not consume additional energy or increase net CO 2 emissions. Renewable sources like solar energy provide readily available and continuous light supply required for driving this conversion process. Therefore, the use of solar energy to drive CO 2 photocatalytic reactions simultaneously addresses the aforementioned challenges, while producing sustainable fuels or chemicals suitable for use in existing energy infrastructure. Recent progress in this area has focused on the development and testing of promising TiO 2 based photocatalysts in different reactor configurations due to their unique physicochemical properties for CO 2 photoreduction. TiO 2 nanostructured materials with different morphological and textural properties modified by using organic and inorganic compounds as photosensitizers (dye sensitization), coupling semiconductors of different energy levels or doping with metals or non-metals have been tested. This review presents contemporary views on state of the art in photocatalytic CO 2 reduction over titanium oxide (TiO 2 ) nanostructured materials, with emphasis on material design and reactor configurations. In this review, we discuss existing and recent TiO 2 based supports, encompassing comparative analysis of existing systems, novel designs being employed to improve selectivity and photoconversion rates as well as emerging opportunities for future development, crucial to the field of CO 2 photocatalytic reduction. The influence of different operating and morphological variables on the selectivity and efficiency of CO 2 photoreduction is reviewed. Finally, perspectives on the progress of TiO 2 induced photocatalysis for CO 2 photoreduction will be presented.