Review on Electrocatalytic CO2 Reduction: From Molecular Mechanisms to Scalable Systems

Electrochemical CO2 reduction (eCO2RR) is an effective strategy for converting CO2 into value-added products to reduce the global carbon footprint. It offers distinct advantages over other ways of CO2 reduction from a commercial perspective due to its wide range and higher selectivity of products, as well as its ease of integration with growing renewable energy infrastructure. The primary limitations of state-of-the-art eCO2RR catalysts currently in the market are high overpotential, slow reaction kinetics, low stability, and insufficient selectivity of C2+ products. Material design challenges primarily impede adequate commercialization due to a lack of appropriate cathode material and high product separation cost. Substantial progress has been achieved in the past decade in cathode material development with enhanced energy efficiency, stability, and superior selectivity, which is reviewed in detail in terms of the catalytic centers. However, to overcome the various technical and scientific difficulties in realizing industrial demands, efficient process engineering is essential. Special emphasis is given to thermodynamic and kinetic parameters as well as process conditions like reactor design, effects of organic/inorganic electrolytes, and pH. Various mechanistic pathways for selective product formation, technoeconomic analysis, and various stability concerns for practical implementation of eCO2RR are also comprehensively reviewed to offer a holistic approach.