Electrochemical reduction of CO 2 using renewable energy is a promising strategy to mitigate the CO 2 emissions and to produce valuable chemicals. However, the lack of highly selective, highly durable, and nonpreciousmetal catalysts impedes the applications of this reaction. In this work, coppernanowire-supported indium catalysts are proposed as advanced electrocatalysts for the aqueous electroreduction of CO 2 . The catalysts are synthesized by a facile method, which combines In 3+ deposition on Cu(OH) 2 nanowires, mild oxidation, and in situ electroreduction procedures. With a thin layer of metallic In deposited on the surface of the Cu nanowires, the catalyst exhibits a CO Faradaic efficiency of ∼93% at −0.6 to −0.8 V vs RHE; additionally, an unprecedented stability of 60 h is achieved. The characterization results combined with density functional theory (DFT) calculations reveal that the interface of Cu and In plays an essential role in determining the reaction pathway. The calculation results suggest that the Cu−In interface enhances the adsorption strength of *COOH, a key reaction intermediate for CO production, while destabilizes the adsorption of *H, an intermediate for H 2 evolution. We believe that these findings will provide guidance on the rational design of high-performance bimetallic catalysts for CO 2 electroreduction by creating the metal−metal interface structure.

Fe, Co, Ni and Cu are the main non-noble industrially significant catalysts in the CO2 and CO gas phase hydrogenation reaction towards hydrocarbons and alcohols. These catalysts are typically supported on metal oxides such as SiO2, TiO2, Al2O3 and ZnO, in order to maximize the activity towards the desired reaction. The role of the supporting material is to stabilize the catalytic nanoparticles and to prevent sintering at the elevated reaction temperatures and pressures. The supporting phase can improve the reaction activity or even have a crucial role in the reaction, as is the case, e.g. for the Methanol synthesis over Cu based catalysts on ZnO. Studying the metals without a supporting oxide phase is of capital importance for the fundamental understanding of the catalytic activity of the metal phase. Therefore, we investigated the pristine transition metals Fe, Co, Ni and Cu (diluted with silica glass beads to avoid sintering) towards their activity in the CO2 hydrogenation reaction and determined the activation energy. An Al2O3 supported Ruthenium catalyst with 0.5 mass percent of Ru loading was taken as reference system. It was found that Co, Ni and Ru/Al2O3 are mostly active in the Sabatier reaction, while Fe is active in the reverse water gas shift reaction. Cu as pristine metal shows no catalytic activity. C2+ hydrocarbons were formed on Co in low concentrations. For the calculation of the activation energy, the kinetically determined temperature range of the reaction is identified with a high resolution in time by means of a quantitative gas analysis method with an online mass spectrometer. The activation energy of the CO2 hydrogenation reaction was determined to be 50 kJ/mol over Fe, 77 kJ/mol over Co, 74 kJ/mol over Ni and 73 kJ/mol over the Ru/Al2O3 catalyst, indicating similar reaction pathways over Co, Ni and Ru/Al2O3 and a different reaction mechanism on Fe.

This study analyses the power to methane and the power to methanol processes in the view of their efficiency in energy storage. A systematic investigation of the differences on the two production systems is performed. The energy storage potential of CO2 to methanol and methane is assessed in a progressive way, from the ideal case to the real process. In ideal conditions, where no additional energy is required for the reaction and CO2 is fully converted into products, energy storage is 8 % more efficient in methanol than methane. However, the Sabatier reaction can be performed with a lower degree of complexity than the CO2 to methanol reaction. For this reason, the methanol production process is analysed in detail. The influence of the process configuration and the energy requirements for the various necessary unit operations is investigated, and a ranking among various the alternatives is obtained. Single stage, recycle and cascade reactors are compared and assessed in terms of energy requirements for the operation and energy storage in the product. For small scale applications, the cascade reactor is the most suitable process technology, because it does not require additional energy and allows high yield to methanol. With the current technology, we demonstrate that a hybrid process, including both the CO2 hydrogenation to methanol and methane, is the most effective method to achieve a high conversion of renewable energy to carbon-based fuels with a significant fraction of liquid product.