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

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.