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Decreasing the emission carbon dioxide (CO2) into atmosphere is one of most important issues for human society to develop the sustainable environment. Electrochemical reduction of CO2 has received considerable attraction. It is considered as a potential method to develop the sustainable energy conversion, to reduce the CO2 emission, and to increase the efficiency of consumed energy. Previous studies have investigated metal catalysts as electrochemical heterogeneous catalysts to convert CO2 highly efficiently to fuel products with high economic values, such as methane, ethane, formate and carbon monoxide.[1] However, high overpotential and therefore high energy input are needed to electrochemically reduce CO2, because high energy barriers between the reactant CO2 and the chemical fuel products. Kanan�s group has recently developed the oxide-derived metal to successfully decrease the overpotential.[2] Rosen's group has found out nano-porous silver as electrocatalysts with lower overpotential, higher current efficiency and current density.[3]
In this work we use chloride-derived silver as electrocatalysts for CO2 reduction. By modifying the surface morphology and composition of silver metal using chloride, the reduction CO2 to CO current efficiency is increased to 84%, compared to 2% for pure silver metal at -0.6 V (vs. reversible hydrogen electrode, RHE), and the CO partial current density is 190 times of that for pure silver. The changes of surface morphology for the chloride-derived silver before and after catalytic reaction are studied by scanning electron microscopy (SEM). The roles of chloride and silver to the reaction are investigated by X-ray photon spectroscopy (XPS). Our study opens up new strategies to design catalysts with enhanced catalytic performance for CO2 reduction and other sustainable development by modifying the structure and thus the properties of materials.
[1] Hori, Y. Modern aspects of electrochemistry. Springer New York, 2008. 89-189.
[2] Li, C. W., & Kanan, M. W. J. Am. Chem. Soc. (2012), 134(17), 7231.
[3] Lu, Q., et al.. Nature Communications (2014), 5, 3242.
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