Titanium Carbide (Ti₃C₂) MXene as a Promising Co-catalyst for Photocatalytic CO₂Conversion to Energy-Efficient Fuels: A Review

Photocatalytic CO2 reduction to produce valuable chemicals and fuels using solar energy provides an appealing route to alleviate global energy and environmental problems. However, available semiconductor materials are less efficient to promote CO2 conversion to energy-efficient fuels. In the current development, titanium carbide (Ti3C2) MXene as a co-catalyst with a high conductivity, abundant active sites, and large specific surface area, is a preeminent candidate to promote semiconductor photoactivity. This review provides an overview in the utilization of Ti3C2 as a promising co-catalyst for maximizing CO2 reduction efficiency and product selectivity. In the mainstream, developments in Ti3C2 MXene-based composites for CO2 conversion through different processes, such as CO2 reduction with water, photocatalytic CO2 methanation, and natural gas flaring reduction to synthesis gas, have been discussed. The review also gives an overview of the factors crucial to affect photocatalytic properties of Ti3C2, such as morphological, electrical, optical, and luminescence characteristics. The fundamental mechanism of Ti3C2Tx for photocatalytic reduction of CO2 and strategies to improve the photocatalytic performance are also described. The great emphasis is given on in situ TiO2 production and hybridization with other semiconductors to obtain an efficient co-catalyst for selective CO2 reduction. Lastly, conclusions and future prospectives to further explore in the field of energy and fuels are included.