Nanomaterials as catalysts for CO₂ transformation into value-added products: A review

Carbon dioxide (CO₂₎ is the most important greenhouse gas (GHG), accounting for 76% of all GHG emissions. The atmospheric CO₂ concentration has increased from 280 ppm in the pre-industrial era to about 418 ppm, and is projected to reach 570 ppm by the end of the 21^st century. In addition to reducing CO₂ emissions from anthropogenic activities, strategies to adequately address climate change must include CO₂ capture. To promote circular economy, captured CO₂ should be converted to value-added materials such as fuels and other chemical feedstock. Due to their tunable chemistry (which allows them to be selective) and high surface area (which allows them to be efficient), engineered nanomaterials are promising for CO₂ capturing and/or transformation. This work critically reviewed the application of nanomaterials for the transformation of CO₂ into various fuels, like formic acid, carbon monoxide, methanol, and ethanol. We discussed the literature on the use of metal-based nanomaterials, inorganic/organic nanocomposites, as well as other routes suitable for CO₂ conversion such as the electrochemical, non-thermal plasma, and hydrogenation routes. The characteristics, steps, mechanisms, and challenges associated with the different transformation technologies were also discussed. Finally, we presented a section on the outlook of the field, which includes recommendations for how to continue to advance the use of nanotechnology for conversion of CO₂ to fuels.