Recent advances in TiO2-based photocatalysts for CO2 reduction to methane

Abstract

Photocatalytic CO₂ reduction reaction (CO₂RR) is one of the strategies to mitigate the greenhouse effect, in which the generation of CH₄ as a high-calorific-value clean energy source has attracted much attention. Among many photocatalysts, titanium dioxide (TiO₂) is more attractive due to its controllable energy band structure and other advantages. However, its wide forbidden band leads to low light utilization and catalytic capacity. Therefore, tuning the energy band structure and absorbance range of TiO₂ to improve CO₂RR efficiency has become a research focus. On the basis of few reviews on the research progress of photocatalytic CO₂RR to CH₄ from TiO₂-based composites, this paper firstly comprehends the principle and reaction pathway of photocatalytic CO₂RR, and introduces the influence of the dosage of the main reactants (H₂O and CO₂) on the photocatalytic process, as well as the preparation method of the TiO₂-based catalysts. Then the research progress of TiO₂-based catalysts in the field of CO₂RR to CH₄ photocatalysis (e.g., construction of TiO₂ heterojunction, surface modification, elemental doping, metal-organic frameworks (MOF)/TiO₂, etc.) is reviewed, which provide guidance for the design of photocatalysts with excellent performance. Finally, challenges and research opportunities are discussed and outlooked.