The electrochemical reduction of CO 2 has seen many record-setting advances in C 2 productivity in recent years. However, the selectivity for ethanol, a globally significant commodity chemical, is still low compared to the selectivity for products such as ethylene. Here we introduce diverse binding sites to a Cu catalyst, an approach that destabilizes the ethylene reaction intermediates and thereby promotes ethanol production. We develop a bimetallic Ag/Cu catalyst that implements the proposed design toward an improved ethanol catalyst. It achieves a record Faradaic efficiency of 41% toward ethanol at 250 mA/cm 2 and −0.67 V vs RHE, leading to a cathodic-side (half-cell) energy efficiency of 24.7%. The new catalysts exhibit an in situ Raman spectrum, in the region associated with CO stretching, that is much broader than that of pure Cu controls, a finding we account for via the diversity of binding configurations. This physical picture, involving multisite binding, accounts for the enhanced ethanol production for bimetallic catalysts, and presents a framework to design multimetallic catalysts to control reaction paths in CO 2 reductions toward desired products.

The process of CO2 valorizationfrom capture of CO2 to its electrochemical upgraderequires significant inputs in each of the capture, upgrade, and separation steps. Here we report an electrolyzer that upgrades carbonate electrolyte from CO2 capture solution to syngas, achieving 100% carbon utilization across the system. A bipolar membrane is used to produce proton in situ to facilitate CO2 release at the membrane:catalyst interface from the carbonate solution. Using a Ag catalyst, we generate syngas at a 3:1 H2:CO ratio, and the product is not diluted by CO2 at the gas outlet; we generate this pure syngas product stream at a current density of 150 mA/cm2 and an energy efficiency of 35%. The carbonate-to-syngas system is stable under a continuous 145 h of catalytic operation. The work demonstrates the benefits of coupling CO2 electrolysis with a CO2 capture electrolyte on the path to practicable CO2 conversion technologies.

Abstract. Gas-particle partitioning governs the distribution, removal, and transport of organic compounds in the atmosphere and the formation of secondary organic aerosol (SOA). The large variety of atmospheric species and their wide range of properties make predicting this partitioning equilibrium challenging. Here we expand on earlier work and predict gas-organic and gas-aqueous phase partitioning coefficients for 3414 atmospherically relevant molecules using COSMOtherm, SPARC Performs Automated Reasoning in Chemistry (SPARC), and poly-parameter linear free-energy relationships. The Master Chemical Mechanism generated the structures by oxidizing primary emitted volatile organic compounds. Predictions for gas-organic phase partitioning coefficients (K WIOM/G ) by different methods are on average within 1 order of magnitude of each other, irrespective of the numbers of functional groups, except for predictions by COSMOtherm and SPARC for compounds with more than three functional groups, which have a slightly higher discrepancy. Discrepancies between predictions of gas-aqueous partitioning (K W/G ) are much larger and increase with the number of functional groups in the molecule. In particular, COSMOtherm often predicts much lower K W/G for highly functionalized compounds than the other methods. While the quantum-chemistry-based COSMOtherm accounts for the influence of intra-molecular interactions on conformation, highly functionalized molecules likely fall outside of the applicability domain of the other techniques, which at least in part rely on empirical data for calibration. Further analysis suggests that atmospheric phase distribution calculations are sensitive to the partitioning coefficient estimation method, in particular to the estimated value of K W/G . The large uncertainty in K W/G predictions for highly functionalized organic compounds needs to be resolved to improve the quantitative treatment of SOA formation.