Covalent Organic Frameworks Boost the Silver-Electrocatalyzed Reduction of CO₂: The Electronic and Confinement Effect

Abstract

The electrocatalytic reduction of CO2 to CO with high efficiency is one of the most promising approaches for CO2 conversion due to its considerable economic feasibility and broad application prospects. In this study, three Ag@COF-R (R = −H, −OCH3, −OH) hybrids were facilely fabricated by impregnating silver acetate (AgOAc) into respective covalent organic frameworks (COFs) prepared in advance. They differ significantly in the crystallinity, porosity, distribution, size, and electronic configuration of AgOAc species, which thereby influences both the activity and the selectivity of electrolytic CO2-to-CO transformation. Impressively, Ag@COF-OCH3 provided a high FECO of 93.0% with a high j CO of 213.9 mA cm–2 at −0.87 V (vs reversible hydrogen electrode, RHE) in 1 M KOH using a flow cell. In addition, it exhibited long-term durability at 100 mA cm–2 for 30 h.

Modulating the Active Sites of VS2 by Mn Doping for Highly Selective CO2 Electroreduction to Methanol in a Flow Cell

“…Flow cells with a gas diffusion electrode (GDE) can produce chemicals under industrial-scale current densities in the aqueous electrolyte by overcoming the mass transport limitation of CO 2 . − To date, only several catalysts have been explored for the conversion of CO 2 ER to methanol in flow cells. Intermetallic CuGa 2 can electrocatalyze CO 2 to methanol with a Faradic efficiency of 77.26% at −0.3 V in a flow cell, but its Faradic efficiency quickly decreases to less than 15% at a higher potential owing to the in situ reduction of the active component of surface and subsurface Ga 2 O 3 .…”