Tandem design on electrocatalysts and reactors for electrochemical CO2 reduction

Electrochemical CO2 reduction (ECR) driven by intermittent renewable energy sources is an emerging technology to achieve net-zero CO2 emissions. Tandem electrochemical CO2 reduction (T-ECR), employs tandem catalysts with synergistic or complementary functions to efficiently convert CO2 into multi-carbon (C2+) products in a succession of reactions within single or sequentially coupled reactors. However, the lack of clear interpretation and systematic understanding of T-ECR mechanisms has resulted in suboptimal current outcomes. This review presents new perspectives and summarizes recent advancements in efficient T-ECR across various scales, including synergistic tandem catalysis at the microscopic scale, relay tandem catalysis at the mesoscopic scale, and tandem reactors at the macroscopic scale. We begin by outlining the principle of tandem catalysis, followed by discuss on tandem catalyst design, the electrode construction, and reactor configuration. Additionally, we address the challenges and prospects of tandem strategies, emphasizing the integration of machine learning, theoretical calculations, and advanced characterization techniques for developing industry-scale CO2 valorization. © 2025 Dalian Institute of Chemical Physics, the Chinese Academy of Sciences