Tandem catalysis in electrochemical CO₂ reduction reaction

Electrochemical CO₂ reduction reaction (CO₂RR) is an attractive pathway for closing the anthropogenic carbon cycle and storing intermittent renewable energy by converting CO₂ to valuable chemicals and fuels. The production of highly reduced carbon compounds beyond CO and formate, such as hydrocarbon and oxygenate products with higher energy density, is particularly desirable for practical applications. However, the productivity towards highly reduced chemicals is typically limited by high overpotential and poor selectivity due to the multiple electron-proton transfer steps. Tandem catalysis, which is extensively utilized by nature for producing biological macromolecules with multiple enzymes via coupled reaction steps, represents a promising strategy for enhancing the CO₂RR performance. Improving the efficiency of CO₂RR via tandem catalysis has recently emerged as an exciting research frontier and achieved significant advances. Here we describe the general principles and also considerations for designing tandem catalysis for CO₂RR. Recent advances in constructing tandem catalysts, mainly including bimetallic alloy nanostructures, bimetallic heterostructures, bimetallic core-shell nanostructures, bimetallic mixture catalysts, metal-metal organic framework (MOF) and metal-metallic complexes, metal-nonmetal hybrid nanomaterials and copper-free hybrid nanomaterials for boosting the CO₂RR performance are systematically summarized. The study of tandem catalysis for CO₂RR is still at the early stage, and future research challenges and opportunities are also discussed.