(285g) Engineering Cu Nanostructures for CO2 Reduction

Electrochemical reduction of CO₂, an artificial way of carbon recycling, represents one promising solution for energy and environment sustainability. Despite the many advantages, electrochemical reduction of CO₂ is challenged by the absence of efficient catalysts for this reaction. Copper (Cu) is the most studied material capable of catalyzing CO₂ reduction at significant rates, but it still requires large overpotentials; e.g., to reach a current density of 1 mA/cm²on polycrystalline Cu electrode, it typically requires an overpotential of >0.5 V for producing CO and HCOOH (two-electro processes) and >0.8 V for further reduced products such as CH₄ and C₂H₄. Moreover, hydrogen evolution competes with CO₂ reduction, reducing the Faradaic efficiency (FE) towards carbon-containing compounds. Here we report the synthesis of highly dense Cu nanowires and their superior performance for electrocatalytic CO₂ reduction. CuO nanowires were first grown thermal treatment of Cu gauze in air, which were then subjected to electrochemical reduction or annealing in a reducing atmosphere to form Cu nanowires . The obtained Cu nanowires were then applied as electrocatalysts for CO₂ reduction. These nanowires were found to be highly active at the low-overpotential regions, i.e., E ≤ 0.5 V, and also possess high selectivity for CO2 reduction. The electrocatalytic performance was further found to depend on the nanostructures of the nanowires that gave rise to surface sites catalyzing CO2 reduction efficiently.