Low-Coordinated Edge Sites on Ultrathin Palladium Nanosheets Boost Carbon Dioxide Electroreduction Performance.

Electrochemical conversion of carbon dioxide (CO2 ) to value-added products is a possible way to decrease the problems resulting from CO2 emission. Thanks to the eminent conductivity and proper adsorption to intermediates, Pd has become a promising candidate for CO2 electroreduction (CO2 ER). However, Pd-based nanocatalysts generally need a large overpotential. Herein we describe that ultrathin Pd nanosheets effectively reduce the onset potential for CO by exposing abundant atoms with comparatively low generalized coordination number. Hexagonal Pd nanosheets with 5 atomic thickness and 5.1 nm edge length reached CO faradaic efficiency of 94 % at -0.5 V, without any decay after a stability test of 8 h. It appears to be the most efficient among all of Pd-based catalysts toward CO2 ER. Uniform hexagonal morphology made it reasonable to build models and take DFT calculations. The enhanced activity originates from mainly edge sites on palladium nanosheets.