Carbon dioxide conversion to value-added products and fuels: opportunities and challenges: a critical review

Carbon dioxide (CO2) conversion to value-added products and fuels is one of the most promising approaches to reducing CO2 accumulation in the environment and resolving the scarcity of sustainable energy. Renewable carbon may be an alternative source to avoid combustible products such as petroleum and coal in order to decrease CO2 emissions. It is necessary to introduce the latest technologies and procedures to mature novel carbon recycling methods for CO2.The value-added products can be synthesized by using photocatalysis, electrochemical (ECR), thermochemical, and bio-electrochemical reduction processes, along with homogeneous and heterogeneous catalysts. Among such techniques, CO2 conversion by photocatalysis plays an important role in resolving global warming and the energy crisis. Researchers developed CO2 hydrogenation catalysts for the production of alcohols, liquid fuels, dimethyl ether, and light olefins through Fischer-Tropsch and methanol reactions. Photoelectrochemical CO2 conversion produces formic acid, formaldehyde, formate, methane, ethanol, and methanol and is reflected as an artificial photosynthesis method. Due to the huge energy demand, extensive efforts have been made for alternative, cheap, eco-friendly, highly efficient, economical, and marketable reduction processes and products. It has been known that slag residues with high temperatures from iron and steel factories can be used as a source of energy. Catalyst stability, selectivity, yields, and activity have been future challenges for achieving indispensable conversion processes. In this review, current advancements in conversion processes, mechanisms, catalysts, and carbon capture systems have been broadly reviewed. Furthermore, the challenges associated with its advancement are also illustrated. This review will have a positive impact on carbon dioxide mitigation and production, which are highly efficient with significant applications of value-added products.