A review on electrochemical CO2-to-CH4 conversion for a sustainable energy future: from electrocatalysts to electrolyzers

Abstract

The electrochemical reduction of carbon dioxide (CO₂) to methane (CH₄) offers a promising route to renewable fuels and carbon circularity, addressing urgent climate and energy challenges. However, key bottlenecks such as limited selectivity, sluggish reaction kinetics, and insufficient long-term stability still hinder the practical deployment of this reaction and technology. Fundamental research has uncovered promising electrocatalysts and mechanistic insights to overcome these limitations, yet translating these advances into scalable industrial solutions remains a major challenge. This review addresses this critical gap by providing a comprehensive and focused overview of electrochemical CO₂-to-CH₄ conversion, from fundamental reaction mechanisms to system-level implementation. This work systematically analyzes the most selective and active electrocatalysts developed to date, elucidating key design principles that govern CH₄ production. In addition, we assess the evolution of CO₂ electrolyzers tailored for CH₄, comparing device configurations, operational strategies, and levels of technological maturity. Techno-economic evaluations are also integrated to identify bottlenecks and realistic near-term implementation scenarios. As the demand for green CH₄ rises at a pace that outstrips conventional CH₄ growth, this technology emerges as a timely solution to decarbonize hard-to-abate sectors using renewable electricity.