Constructing 2D Phthalocyanine Covalent Organic Framework with Enhanced Stability and Conductivity via Interlayer Hydrogen Bonding as Electrocatalyst for CO2 Reduction

Abstract

AbstractFabricating COFs‐based electrocatalysts with high stability and conductivity still remains a great challenge. Herein, 2D polyimide‐linked phthalocyanine COF (denoted as NiPc‐OH‐COF) is constructed via solvothermal reaction between tetraanhydrides of 2,3,9,10,16,17,23,24‐octacarboxyphthalocyaninato nickel(II) and 2,5‐diamino‐1,4‐benzenediol (DB) with other two analogous 2D COFs (denoted as NiPc‐OMe‐COF and NiPc‐H‐COF) synthesized for reference. In comparison with NiPc‐OMe‐COF and NiPc‐H‐COF, NiPc‐OH‐COF exhibits enhanced stability, particularly in strong NaOH solvent and high conductivity of 1.5 × 10−3 S m−1 due to the incorporation of additional strong interlayer hydrogen bonding interaction between the O−H of DB and the hydroxy “O” atom of DB in adjacent layers. This in turn endows the NiPc‐OH‐COF electrode with ultrahigh CO2‐to‐CO faradaic efficiency (almost 100%) in a wide potential range from −0.7 to −1.1 V versus reversible hydrogen electrode (RHE), a large partial CO current density of −39.2 mA cm−2 at −1.1 V versus RHE, and high turnover number as well as turnover frequency, amounting to 45 000 and 0.76 S−1 at −0.80 V versus RHE during 12 h lasting measurement.