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

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 Cubased bimetallic catalysts. Moreover, the morphology of sharpened catalysts was relatively random and nonuniform, 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.