Electric-field-driven electrochemical CO2 reduction of sharpened Sn/Cu catalysts

Abstract

Sharpening of noble metal catalysts has been proven to enhance the performance of CO2 electrochemical reduction to CO. However, this approach has not been validated for non-precious metal catalysts such as Cu-based bimetallic catalysts. Moreover, the morphology of sharpened catalysts was relatively random and non-uniform, making it difficult to quantify the curvature of nanostructures. Here, we experimentally studied the relationship between sharpness of Sn/Cu catalysts with their activity through the fabrication of Sn/Cu foil, rods, and cones. The Sn/Cu catalysts were fabricated by template-based nanoimprint lithography, electroplating of Cu film, and electroless coating of Sn nanoparticles. The finite-element-based simulation provides evidence that the local electric field intensified as the curvature of catalysts increased. As a result, Sn/Cu cones exhibited much better faradaic efficiency of CO (FECO) = 82.7% and current density of CO (jCO) = 5.43 mA/cm2 than Sn/Cu foil (FECO = 41.3% and jCO = 2.29 mA/cm2) and Sn/Cu rods (FECO = 59.7% and jCO = 3.87 mA/cm2). This work reveals that the local electric field induced by the sharp tip plays a significant role in improving the FECO and lowering the onset potential of CO2 reduction reaction.