Surface Processes in Photocatalytic Reduction of CO2 on TiO2-based Materials

Owing to its excellent photoactivity, good stability and low cost, TiO₂ is one of the most studied semiconductor materials to convert CO₂ into useful chemicals, contributing to mitigate global warming. In this review, starting from the basic kinetic and thermodynamic principles of CO₂ photoreduction, the focus is on the surface processes involved in its capture and subsequent reactivity on TiO₂. In particular, the role of different TiO₂ morphologies, facets and surface heterostructures is discussed. The effect of relevant co-adsorbed molecules (e.g., H₂O) on the CO₂ reaction pathways is also considered. Moreover, the coupling of TiO₂ with graphene and metal nanoparticles to enhance the reaction rates is presented. A deeper understanding at the atomic level of these surface mechanisms could help the design of TiO₂-based photocatalysts with improved efficiency and selectivity.