Facile solid-state synthesis of 2D-Cu-sheet catalyst for efficient CO₂ electroreduction to ethanol

The conversion of carbon dioxide (CO₂) into synthetic hydrocarbons attracts substantial attention due to its environmental advantage and economic value. Specifically, the electrochemical conversion of CO₂ (CO₂RR) to ethanol (C₂H₅OH) highlights the importance of this approach toward high value-added chemicals. We report herein, the successful synthesis of a two-dimensional copper-layered catalyst (2D-Cu-sheet), designed for CO₂RR to C₂H₅OH. The synthesis strategy involves a solid-state reaction using copper salts, graphite, and aluminum, followed by a fluorine-free alkali-assisted exfoliation process to eliminate interlayer species, and obtained high-purity ultrathin 2D-Cu-sheet architecture. These sheets exhibit significant electrocatalytic activity and selectivity for CO₂RR to C₂H₅OH in a flow cell system, surpassing the performance of conventional copper (Cu) catalysts with low selectivity, and commonly studied 2D Ti₃C₂T_x MXene known for producing carbon monoxide (CO) with 55 % FE at the same operating conditions. The electrochemical performance of the developed catalyst achieved 54.4 % Faradaic efficiency (FE) for ethanol at −0.73 V vs. RHE with a Tafel slope of 56.5 mV·dec⁻¹ and an electrochemically active surface area (ECSA) of 10 m²·g⁻¹. Additionally, the catalyst demonstrated an electrochemical stability of 70 h at an operating current density of 150 mA/cm² in a continuous flow cell. The excellent performance of the synthesized 2D-Cu-sheet could be attributed to the presence of a high exposed active surface area with defective nanograin morphology and the presence of Cu in {111} crystal faces, active and enabling C-C couplings for the production of C₂-prodcuts (specifically ethanol). The outcomes of this study could be potentially useful for CO₂ valorization to value-added chemicals, while simultaneously reducing the carbon footprint through emission processes.