Status and perspectives of CO2 conversion into fuels and chemicals by catalytic, photocatalytic and electrocatalytic processes

TLDR

CO₂ is being explored for sustainable energy and chemical production to mitigate global warming, yet commercial electrocatalytic reduction still requires major advances in electrodes, electrolytes, and reactor design. This review focuses on designing metal electrodes, employing ionic liquids and microorganisms, and developing rational material strategies to enhance CO₂ conversion using H₂, electricity, or light. It surveys heterogeneous hydrogenation, photocatalytic, and electrocatalytic CO₂ conversion pathways, evaluates CO₂‑neutral hydrogen sources, and discusses electrode, electrolyte, and reactor innovations. Large‑scale CO₂ hydrogenation to methanol or methane exists, but industrial uptake is constrained by expensive renewable hydrogen and limited pure CO₂ supplies, and photocatalytic CO₂ functionalization still needs major catalyst and reactor improvements to be viable.

Abstract

This review highlights recent developments and future perspectives in carbon dioxide usage for the sustainable production of energy and chemicals and to reduce global warming. We discuss the heterogeneously catalysed hydrogenation, as well as the photocatalytic and electrocatalytic conversion of CO2 to hydrocarbons or oxygenates. Various sources of hydrogen are also reviewed in terms of their CO2 neutrality. Technologies have been developed for large-scale CO2 hydrogenation to methanol or methane. Their industrial application is, however, limited by the high price of renewable hydrogen and the availability of large-volume sources of pure CO2. With regard to the direct electrocatalytic reduction of CO2 to value-added chemicals, substantial advances in electrodes, electrolyte, and reactor design are still required to permit the development of commercial processes. Therefore, in this review particular attention is paid to (i) the design of metal electrodes to improve their performance and (ii) recent developments of alternative approaches such as the application of ionic liquids as electrolytes and of microorganisms as co-catalysts. The most significant improvements both in catalyst and reactor design are needed for the photocatalytic functionalisation of CO2 to become a viable technology that can help in the usage of CO2 as a feedstock for the production of energy and chemicals. Apart from technological aspects and catalytic performance, we also discuss fundamental strategies for the rational design of materials for effective transformations of CO2 to value-added chemicals with the help of H2, electricity and/or light.