Cu-Based Tandem Architectures for CO2 Electrolysis to Multicarbon Products

Carbon dioxide electroreduction reaction (CO₂RR) offers a pathway to convert CO₂ into valuable multicarbon products (C₂₊), potential clean energy, and chemical vectors, using renewable electricity. Copper catalysts are, so far, the most selective in this process, but still face challenges such as high overpotentials and insufficient selectivity and stability when used alone. One strategy to tackle these is the use of Cu-based tandem structures, which incorporate tailored reaction sites to drive a segment of the CO₂RR reaction, in a more favorable way, within the same electrode. Recent examples have shown how Cu-tandem catalysts can lead to voltage savings and improvements in selectivity. This review analyses various Cu-based tandem catalysts, focusing on alloys, heterostructures (especially highlighting the role of polymer coatings in achieving tandem effects through environmental control), and metal–organic frameworks (MOFs). It covers synthetic strategies to achieve tandem-enabling configurations and their suggested impact on reaction mechanisms and performance improvement toward C₂₊ electrosynthesis. The review concludes by offering a roadmap toward the design of more efficient Cu-based tandem electrodes for CO₂RR and beyond.