Chapter 25 - Supported single-atom catalysts in carbon dioxide electrochemical activation and reduction

Abstract

The electrochemical reduction of CO2 is more attractive compared to its thermal counterpart as it allows for the utilization of renewable energy and electron-driven processes to convert CO2 into value-added chemicals and fuels. Single-atom catalysts (SACs) are catalytic systems in which metals are dispersed onto solid conductor support providing well-defined mononuclear, low coordinated, open active metal sites similar to homogeneous metal complexes. Defects in SAC 2-dimensional supports alter the basal and edge planes of the 2-dimensional material crystals, inducing additional electronic, magnetic, and electrocatalytic properties into the metal active center. SACs have attracted wide attention in catalysis, including CO2 electrochemical reduction reaction (CO2ERR), due to the presence of quantum effects and the maximum usage of active transition metals to achieve high reaction activity and selectivity whiles reducing cost. Despite the potential of CO2 electrochemical reduction to attack the problem of climate change, current catalytic performances of SACs (selectivity, activity, and stability) are limited. The structure-performance indicators of catalytic surfaces are unique to the varied array of CO2 reactions and products. The conversion of CO2 to hydrocarbons is a multistep reaction that requires experimentation to identify key intermediates and barriers encountered, to control reaction outcomes. Herein, we discuss the research findings and directions underway to shed light on the molecular level CO2ERR on SAC and the structural-performance indicators identified thus far. We highlight both experimental and theoretical findings and provide research gaps in the field of CO2 electrochemical valorization on SACs.