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The electroreduction of carbon dioxide (CO2) has been emerging as a high‐ potential approach for CO2 utilization using renewables. When copper (Cu) based catalysts are used, this platform can produce multi‐carbon (C2+) fuels and chemicals with almost net‐zero emission, contributing to the closure of the anthropogenic carbon cycle. Nonetheless, the rational design and development of Cu‐based catalysts are critical toward the realization of highly selective and efficient CO2 electroreduction. In this review, first the latest advances in Cu‐catalyzed CO2 electroreduction in the product selectivity and electrocatalytic activity are briefly summarized. Then, recent theoretical and mechanistic studies of CO2 electroreduction on Cu‐based catalysts are investigated, which serve as programs to design catalysts. Strategies for devising Cu catalysts that aim at promoting different key elementary steps for hydrocarbon and C2+ oxygenates production are further summarized. Moreover, challenges in understanding the mechanism, operando investigation of Cu catalysts and reactions, and systems’ influences are also presented. Finally, the future prospects of CO2 electroreduction are discussed.

Climate change, caused by heavy CO emissions, is driving new demands to alleviate the rising concentration of atmospheric CO levels. Enlightened by the photosynthesis of green plants, photo(electro)chemical catalysis of CO 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 CO reduction is widely recognized to possess high efficiencies and potentials for practical application. The efficient and selective electroreduction of CO 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 CO reduction. In order to achieve high selectivity for CO 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 CO electrochemical reduction of metallic catalysts are summarized. The challenges and perspectives in this field are also discussed.

Solar-driven electrochemical carbon dioxide (CO2) reduction is capable of producing value-added chemicals and represents a potential route to alleviate carbon footprint in the global environment. However, the ever-changing sunlight illumination presents a substantial impediment of maintaining high electrocatalytic efficiency and stability for practical applications. Inspired by green plant photosynthesis with separate light reaction and (dark) carbon fixation steps, herein, we developed a redox-medium-assisted system that proceeds water oxidation with a nickel-iron hydroxide electrode under light illumination and stores the reduction energy using a zinc/zincate redox, which can be controllably released to spontaneously reduce CO2 into carbon monoxide (CO) with a gold nanocatalyst in dark condition. This redox-medium-assisted system enables a record-high solar-to-CO photoconversion efficiency of 15.6% under 1-sun intensity, and an outstanding electric energy efficiency of 63%. Furthermore, it allows a unique tuning capability of the solar-to-CO efficiency and selectivity by the current density applied during the carbon fixation.