Understanding the Roadmap for Electrochemical Reduction of CO₂ to Multi-Carbon Oxygenates and Hydrocarbons on Copper-Based Catalysts

TLDR

Electrochemical CO₂ reduction to multi‑carbon oxygenates and hydrocarbons is attractive for renewable energy storage, but C‑C bond formation introduces extra barriers that raise overpotentials and broaden product distributions compared to C1 pathways. The authors seek to clarify the catalytic mechanism to enable design of efficient electrocatalysts that steer CO₂ reduction toward desired C2 products. They review mechanistic pathways for C2 formation on copper catalysts, integrating practical operating‑condition factors. Combining theoretical calculations, surface characterization, and electrochemical data, the authors outline a roadmap for C2 product generation and resolve key debates at the atomic level.

Abstract

Electrochemical reduction of CO2 to high-energy-density oxygenates and hydrocarbons beyond CO is important for long-term and large-scale renewable energy storage. However, the key step of the C-C bond formation needed for the generation of C2 products induces an additional barrier on the reaction. This inevitably creates larger overpotentials and greater variety of products as compared to the conversion of CO2 to C1 products. Therefore, an in-depth understanding of the catalytic mechanism is required for advancing the design of efficient electrocatalysts to control the reaction pathway to the desired products. Herein, we present a critical appraisal of reduction of CO2 to C2 products focusing on the connection between the fundamentals of reaction and efficient electrocatalysts. An in-depth discussion of the mechanistic aspects of various C2 reaction pathways on copper-based catalysts is presented together with consideration of practical factors under electrocatalytic operating conditions. By providing some typical examples illustrating the benefit of merging theoretical calculations, surface characterization, and electrochemical measurements, we try to address the key issues of the ongoing debate toward better understanding electrochemical reduction of CO2 at the atomic level and envisioning the roadmap for C2 products generation.