Robust interaction of cobalt phthalocyanine and nitrogen-doped ordered mesoporous carbon for CO2 reduction paired with the electro-oxidative synthesis of sulfonamide derivatives

Abstract

In this work, a high-performance hybrid electrocatalyst based on cobalt phthalocyanine combined with N-doped ordered mesoporous carbon (CoPc@GIOMC) was developed for CO₂ reduction. To achieve this goal, we designed an innovative paired electrolyzer that integrates CO₂ reduction to CO with the efficient oxidative coupling of certain phenylhydroxylamines to produce biologically important sulfonamide and organosulfone derivatives. The hybrid electrode exhibited a significant partial current density of 33 mA cm⁻² in the selective reduction of CO₂ to CO at an overpotential of 0.57 V vs. RHE (the onset potential was 0.3 V vs. RHE) and a faradaic efficiency of 90% in a near-natural aqueous solution (pH = 7.4). This excellent performance can be attributed to a high nitrogen content, numerous defect sites, and a large surface area of our N-doped mesoporous carbon material, which facilitated the strong and stable attachment of CoPc on GIOMC. Furthermore, in the context of coupling cathodic CO₂ reduction with the synthesis of biologically important sulfonamide and organosulfone derivatives, the electrolysis system demonstrated a high anodic faradaic efficiency, reaching nearly 100% at 6 mA cm⁻² after 135 minutes of electrolysis together with a satisfactory energy efficiency of up to 70%.