Electrochemical CO2 Reduction: A Review toward Sustainable Energy Conversion and Storage

The escalating climate crisis and depletion of fossil fuel reserves demand transformative solutions for sustainable energy storage. Electrochemical CO2 reduction (ECR) has emerged as a promising pathway for converting the most abundant greenhouse gas, CO2, into valuable fuels and chemicals, such as ethanol, methane, methanol, formic acid, and hydrocarbons. By integrating CO2 capture and conversion, ECR mitigates the devastating impact of the atmospheric CO2 levels on climate change and stores renewable energy in chemical bonds, addressing the intermittent challenges of wind and solar power. This review explores the fundamental principles of ECR and highlights the advancements in catalyst design, electrolyte optimization, and reactor configurations that enhance efficiency, scalability, and product selectivity. It compares ECR with conventional energy storage methods and emphasizes its dual role in energy storage and climate mitigation. Although catalysts such as nanostructured copper and bimetallic alloys have achieved significant breakthroughs, however, low selectivity, high overpotentials, and catalyst degradation remain a grand challenge. This study further examines the environmental and economic viability of ECR, underscoring the pivotal role of renewable energy integration and life cycle analysis (LCA). By providing insights into industrial applications, research frontiers, and policy implications, this review positions ECR as a cornerstone technology in transitioning to a circular carbon economy and sustainable energy future.