Understanding the Electrocatalytic Interface: A Review of Advances in CO ₂ ER Mechanisms and Materials

Fossil fuels significantly influence climate change by releasing enormous amounts of greenhouse gases and carbon dioxide (CO2) into the environment, making their continued use a pressing global issue. To mitigate these emissions and generate valuable chemicals and fuels, the CO2 electrochemical reduction (CO2ER) presents a promising path toward a sustainable carbon economy. The reduction of CO2 at the cathode of an electrochemical cell is central to the CO2ER reaction, making catalyst selection critical for optimizing the performance, efficiency, and selectivity. The efficiency and selectivity of CO2ER are primarily influenced by the electrolyte composition, reaction conditions (including gas flow, partial pressure, and other thermodynamic aspects), applied current density, and electrode materials. Despite significant progress, key challenges persist, including the design of economical and scalable electrocatalysts. This review offers a comprehensive overview of the underlying mechanisms of the CO2ER, emphasizing key intermediates, reaction pathways, and catalytic challenges. It also highlights recent advancements in electrocatalyst materials, such as bimetallic, metal–organic frameworks, single-atom catalysts, covalent organic frameworks, two-dimensional materials, high-temperature catalysts, and novel hybrid structures engineered to improve performance.