10.1021/acs.chemrev.8b00705.s001 Stephanie Nitopi Stephanie Nitopi Erlend Bertheussen Erlend Bertheussen Soren B. Scott Soren B. Scott Xinyan Liu Xinyan Liu Albert K. Engstfeld Albert K. Engstfeld Sebastian Horch Sebastian Horch Brian Seger Brian Seger Ifan E. L. Stephens Ifan E. L. Stephens Karen Chan Karen Chan Christopher Hahn Christopher Hahn Jens K. Nørskov Jens K. Nørskov Thomas F. Jaramillo Thomas F. Jaramillo Ib Chorkendorff Ib Chorkendorff Progress and Perspectives of Electrochemical CO<sub>2</sub> Reduction on Copper in Aqueous Electrolyte American Chemical Society 2019 research directions catalyst surface structure electrochemical cell design CO 2 R catalysis reaction networks impact CO 2 R activity Electrochemical CO 2 Reduction bimetallic electrodes future outlook catalyst discovery design efforts Aqueous Electrolyte electrolyte ions electrochemical CO 2 R CO 2 R electrochemical CO 2 reduction Cu 2019-05-22 19:34:33 Journal contribution https://acs.figshare.com/articles/journal_contribution/Progress_and_Perspectives_of_Electrochemical_CO_sub_2_sub_Reduction_on_Copper_in_Aqueous_Electrolyte/8171024 To date, copper is the only heterogeneous catalyst that has shown a propensity to produce valuable hydrocarbons and alcohols, such as ethylene and ethanol, from electrochemical CO<sub>2</sub> reduction (CO<sub>2</sub>R). There are variety of factors that impact CO<sub>2</sub>R activity and selectivity, including the catalyst surface structure, morphology, composition, the choice of electrolyte ions and pH, and the electrochemical cell design. Many of these factors are often intertwined, which can complicate catalyst discovery and design efforts. Here we take a broad and historical view of these different aspects and their complex interplay in CO<sub>2</sub>R catalysis on Cu, with the purpose of providing new insights, critical evaluations, and guidance to the field with regard to research directions and best practices. First, we describe the various experimental probes and complementary theoretical methods that have been used to discern the mechanisms by which products are formed, and next we present our current understanding of the complex reaction networks for CO<sub>2</sub>R on Cu. We then analyze two key methods that have been used in attempts to alter the activity and selectivity of Cu: nanostructuring and the formation of bimetallic electrodes. Finally, we offer some perspectives on the future outlook for electrochemical CO<sub>2</sub>R.