Enhanced Carbon Dioxide Electroreduction to Carbon Monoxide over Defect-Rich Plasma-Activated Silver Catalysts

Description

In this work, a plasma oxidation pre-treatment of silver foil enhances the catalytically active sites, which dramatically lowers the overpotential and increases the activity of CO 2 electroreduction to CO. At 0.6 V versus RHE more than 90 % Faradaic efficiency towards CO was achieved on a pre-oxidized silver foil. To understand this we calculated a number of Ag defect structures, including Cu and Au 111 facet and step structures to construct a volcano-like plot. This shows that the not even defects of Ag should be able to reduce CO2 to CO, however by applying an electrical field to the calculations, to simulate the electrochemical environment, it seems that defected Ag site should be able to reduce CO2 towards CO at such low overpotential. Due to the use of the oxygen precusor, to produce such rough Ag samples, also an Ag2O and Ag (111) facet with subsurface oxygen, is included in the vulcano plot. However, these Ag + oxygen structrues are 1) not stable at reducing potential and 2) the strutures bind CO* to strong and should then allow further reduction of CO*. Thus, Ag + oxygen structures is unlikely to be the origin of the low overpotential. 

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