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 Ti3C2T x 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.

Annually billions of cubic meters of natural gas are flared around the globe at various oil and gas production sites. Natural gas flaring practices waste valuable energy resources that can be used for economic support and will also be beneficial to mitigate global warming effects. In this review, an overview of natural gas flaring impacts with respect to the environment with special emphasis on global annual natural gas flaring emissions and their reformation to energy-efficient fuels has been discussed. Initially, natural gas flaring emissions and their impacts in view of environmental pollution and global warming effects have been highlighted. The strategies to mitigate wastage to valuable energy resources through various flaring management strategies are also evaluated. In the main stream, various gas flaring reductions and utilization technologies based on their applications in the oil and gas industry and especially for remote oil and gas fields are discussed. Liquified natural gas (LNG) and compressed natural gas (CNG) technologies have been identified as the main gas flaring reduction methods based on their applicability, commerciality, and economical potential. In addition, gas to liquid (GTL) has been an advancing technology for the past many years toward its utilization of methane as a feed and converting it to useful industrial products such as synthesis crude and methanol. Finally, reformation technologies for synthesis gas (syngas) production such as thermal reforming, plasma reforming, and photoreforming are deliberated. Based on feed gas mixture, different reforming processes such as steam reforming of methane (SRM), dry reforming of methane (DRM), and bi-reforming of methane (BRM) are evaluated for hydrogen-rich syngas production. The future perspectives regarding gas flaring utilization technologies advancement with further improvements in utilization of flared gas to efficient energy fuels are proposed.

Efficient nanomaterials are in high demand in photocatalytic applications to maximize solar energy conversion to renewable fuels. There is growing research on the use of metals as cocatalysts to promote photocatalyst efficiency, but they are expensive. Recently, titanium carbide (Ti3C2T x ) MXenes as layered materials have attracted attention to investigate energy conversion applications. The distinguishing characteristics of Ti3C2T x are higher specific surface area, tunable terminal functional groups (−OH, −O, and −F), exposed metallic active sites, and excellent electrical conductivity. MXenes can be combined with other semiconductors as cocatalysts to improve charge carrier separation. This review discusses various synthesis routes to fabricate Ti3C2T x MXenes as single materials, their surface functionalization, and as cocatalysts to construct a heterojunction for photocatalytic CO2 conversion and H2 production. The different synthesis approaches, such as the HF, halogen, alkali, molten salt, and electrochemical etching routes, to regulate structure, morphology, and efficiency are systematically described. Moreover, synthesis of various morphologies of Ti3C2T x MXenes in terms of dimensions, sizes, and their effect on the performance of energy conversion reactions are systematically discussed. Furthermore, various synthesis routes with regard to fabrication of Ti3C2T x MXene-based nanocomposites for stimulating photocatalytic efficiency with solar energy is elaborated on. The critical analysis and discussion is included on select suitable structures and morphologies of MXenes as cocatalysts and as a support to stimulate the energy harvesting efficiency. Finally, a discussion related to challenges and further developments for exploring pathways in the contexts of synthesis and production of promising renewable fuels is presented.