Precise Site-Hydrophobicity Modulation for Boosting High-Performance CO₂ Electroreduction

Abstract

Electrochemical CO 2 -to-CO conversion is a significant alternative to lower CO 2 emission and build carbon-neutral processes, as well as produce CO, which can directly serve as a syngas precursor for Fischer–Tropsch synthesis. However, the easy water flooding of the gas diffusion electrode (GDE) employed in a flow cell during CO 2 reduction reaction (CO 2 RR) electrolysis remains a tough problem. Consequently, it breaks the electrolyte/catalyst/CO 2 triphase interface and lowers the FE CO . Herein, the combined inarching of amino-substituted cobalt phthalocyanine (CoPc-NH 2 ) and octadecylamine (ODA) onto the surface of the CNT via an amide bond was designed and fabricated. The obtained composite catalyst, labeled as CoPc-CNT-ODA, shows atomically dispersed metal active sites endowed with superior and stable hydrophobicity. When applied to CO 2 RR in a flow cell, the CoPc-CNT-ODA electrode displays a high CO faradic efficiency (FE CO ) of 97.7% and a partial current density ( j CO ) of 154.8 mA·cm –2 at an applied potential of −1.0 V ( vs RHE). Moreover, the FE CO values are all above 90% from −0.8 to −1.2 V ( vs RHE). Even after electrolyzing at −1.0 V for 12 h, the FE CO still remains at 88.3%, implying the superior stability of the CoPc-CNT-ODA electrode. The proposed methodology for GDE/catalyst improvement can be extended to other triphase interfaces involved in catalytic systems.