Electrochemical CO2Reduction to Multicarbon Fuels and Chemicals: Progress and Prospects of Tandem Electrolyzer Strategies

Abstract

Tandem electrolyzer strategies represent an innovative and stepwise evolution toward the commercialization of electrochemical CO2reduction. This review provides a comprehensive introduction to the fundamentals of tandem electrolyzers in catalysis, highlighting their significant advantages over traditional single-cell approaches, particularly in terms of electrical energy efficiency and cost-effectiveness. A detailed discussion is presented on experimental designs, including electrolyzer configurations and optimal reaction environments. Contemporary tandem research is categorized based on targeted products, clearly illustrating how tandem designs enhance performance metrics. By deconvoluting the complex direct conversion of CO2into two or more simplified, independently optimized steps, tandem strategies effectively mitigate or eliminate the persistent challenges of carbon loss and carbonate formation inherent in alkaline CO2reduction. This approach enhances the efficiency of individual reaction steps, improves overall process performance, extends the product range, and enables innovative versatile sequential reaction designs powered by renewable energy. Such strategies offer promising routes to overcoming longstanding barriers in CO2electrolysis, with implications for both industrial deployment and broader decarbonization efforts. Looking ahead, further advances will depend on addressing single-cell issues in catalyst selectivity and stability and on rigorous, tandem-level scale-up demonstrations, accompanied by comprehensive techno-economic analyses.