Journal of Energy Chemistry, 2024

Molecular copper catalysts serve as exemplary models for correlating the structure-reaction-mechanism relationship in the electrochemical CO₂ reduction reaction (eCO₂R), owing to their adaptable environments surrounding the copper metal centres. This investigation, employing density functional theory (DFT) calculations, focuses on a novel family of binuclear Cu molecular catalysts. The modulation of their coordination configuration through the introduction of organic groups aims to assess their efficacy in converting CO₂ to C₂ products. Our findings highlight the crucial role of chemical valence state in shaping the characteristics of binuclear Cu catalysts, consequently influencing the eCO₂R behaviour. Notably, the Cu(II)Cu(II) macrocycle catalyst exhibits enhanced suppression of the hydrogen evolution reaction (HER), facilitating proton transfer and the eCO₂R process. Furthermore, we explore the impact of diverse electron-withdrawing and electron-donating groups coordinated to the macrocycle (R = –F, –H, and –OCH₃) on the electron distribution in the molecular catalysts. Strategic placement of –OCH₃ groups in the macrocycles leads to a favourable oxidation state of the Cu centres and subsequent C–C coupling to form C₂ products. This research provides fundamental insights into the design and optimization of binuclear Cu molecular catalysts for the electrochemical conversion of CO₂ to value-added C₂ products.