Converting carbon dioxide to useful chemicals in a selective and efficient manner remains a major challenge in renewable and sustainable energy research. Silver is an interesting electrocatalyst owing to its capability of converting carbon dioxide to carbon monoxide selectively at room temperature; however, the traditional polycrystalline silver electrocatalyst requires a large overpotential. Here we report a nanoporous silver electrocatalyst that is able to electrochemically reduce carbon dioxide to carbon monoxide with approximately 92% selectivity at a rate (that is, current) over 3,000 times higher than its polycrystalline counterpart under moderate overpotentials of o0.50 V. The high activity is a result of a large electrochemical surface area (approximately 150 times larger) and intrinsically high activity (approximately 20 times higher) compared with polycrystalline silver. The intrinsically higher activity may be due to the greater stabilization of CO 2 À intermediates on the highly curved surface, resulting in smaller overpotentials needed to overcome the thermodynamic barrier.

The electrochemical reduction of carbon dioxide (CO2) has received significant attention in academic research, although the techno-economic prospects of the technology for the large-scale production of chemicals are unclear. In this work, we briefly reviewed the current state-of-the-art CO2 reduction figures of merit, and performed an economic analysis to calculate the end-of-life net present value (NPV) of a generalized CO2 electrolyzer system for the production of 100 tons/day of various CO2 reduction products. Under current techno-economic conditions, carbon monoxide and formic acid were the only economically viable products with NPVs of $13.5 million and $39.4 million, respectively. However, higher-order alcohols, such as ethanol and n-propanol, could be highly promising under future conditions if reasonable electrocatalytic performance benchmarks are achieved (e.g., 300 mA/cm2 and 0.5 V overpotential at 70% Faradaic efficiency). Herein, we established performance targets such that if these targets are achieved, electrochemical CO2 reduction for fuels and chemicals production can become a profitable option as part of the growing renewable energy infrastructure.

Much effort has been devoted in the development of efficient catalysts for electrochemical reduction of CO. Molecular level understanding of electrode-mediated process, particularly the role of bicarbonate in increasing CO reduction rates, is still lacking due to the difficulty of directly probing the electrochemical interface. We developed a protocol to observe normally invisible reaction intermediates with a surface enhanced spectroscopy by applying square-wave potential profiles. Further, we demonstrate that bicarbonate, through equilibrium exchange with dissolved CO, rather than the supplied CO, is the primary source of carbon in the CO formed at the Au electrode by a combination of in situ spectroscopic, isotopic labeling, and mass spectroscopic investigations. We propose that bicarbonate enhances the rate of CO production on Au by increasing the effective concentration of dissolved CO near the electrode surface through rapid equilibrium between bicarbonate and dissolved CO.

Light, inexpensive, effective: Nanostructured Co3O4 clusters (see picture) in mesoporous silica are the first example of a nanometer‐sized multielectron catalyst made of a first‐row transition‐metal oxide that evolves oxygen from water efficiently. The nanorod bundle structure of the catalyst results in a very large surface area, an important factor contributing to the high turnover frequency.