Tuning of CO₂ Reduction Selectivity on Metal Electrocatalysts

Climate change, caused by heavy CO₂ emissions, is driving new demands to alleviate the rising concentration of atmospheric CO₂ levels. Enlightened by the photosynthesis of green plants, photo(electro)chemical catalysis of CO₂ reduction, also known as artificial photosynthesis, is emerged as a promising candidate to address these demands and is widely investigated during the past decade. Among various artificial photosynthetic systems, solar-driven electrochemical CO₂ reduction is widely recognized to possess high efficiencies and potentials for practical application. The efficient and selective electroreduction of CO₂ is the key to the overall solar-to-chemical efficiency of artificial photosynthesis. Recent studies show that various metallic materials possess the capability to play as electrocatalysts for CO₂ reduction. In order to achieve high selectivity for CO₂ reduction products, various efforts are made including studies on electrolytes, crystal facets, oxide-derived catalysts, electronic and geometric structures, nanostructures, and mesoscale phenomena. In this Review, these methods for tuning the selectivity of CO₂ electrochemical reduction of metallic catalysts are summarized. The challenges and perspectives in this field are also discussed.