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Achieving Selective and Efficient Electrocatalytic Activity for CO2 Reduction Using Immobilized Silver Nanoparticles

Kim, Cheonghee, Jeon, Hyo Sang, Eom, Taedaehyeong, Jee, Michael Shincheon, Kim, Hyungjun, Friend, Cynthia M., Min, Byoung Koun, Hwang, Yun Jeong
Journal of the American Chemical Society 2015 v.137 no.43 pp. 13844-13850
carbon, carbon dioxide, catalysts, cysteamine, electrochemistry, electrodes, foil, greenhouse gases, nanosilver, particle size, silver
Selective electrochemical reduction of CO₂ is one of the most sought-after processes because of the potential to convert a harmful greenhouse gas to a useful chemical. We have discovered that immobilized Ag nanoparticles supported on carbon exhibit enhanced Faradaic efficiency and a lower overpotential for selective reduction of CO₂ to CO. These electrocatalysts were synthesized directly on the carbon support by a facile one-pot method using a cysteamine anchoring agent resulting in controlled monodispersed particle sizes. These synthesized Ag/C electrodes showed improved activities, specifically decrease of the overpotential by 300 mV at 1 mA/cm², and 4-fold enhanced CO Faradaic efficiency at −0.75 V vs RHE with the optimal particle size of 5 nm compared to polycrystalline Ag foil. DFT calculations enlightened that the specific interaction between Ag nanoparticle and the anchoring agents modified the catalyst surface to have a selectively higher affinity to the intermediate COOH over CO, which effectively lowers the overpotential.