Electrochemical CO2-to-ethylene conversion on metal-free covalent quinazoline network-derived electrodes

Abstract

Electrocatalytic CO2 reduction to produce multi-carbon (C2+) chemicals represents a highly attractive route for CO2 utilization, particularly CO2-to-ethene conversion toward fuel generation from renewable resources. However, state-of-the-art electrocatalysts are mainly limited to Cu-derived electrodes. Herein, metal-free nanoporous and defect-abundant covalent quinazoline network (CQN)-derived electrocatalysts displayed promising catalytic efficiency and selectivity in CO2-to-ethene conversion. The highest Faradaic efficiency of ethene production (FEC2H4) achieved 61.1% at −1.07 V (versus reversible hydrogen electrode [RHE]) by modified CQN-derived electrodes, surpassing the current metal-free systems in CO2-to-ethene conversion. Structural characterization and theoretical calculation underscored the critical role of defect creation and the periphery nitrogen species in the tricycloquinazoline (TCQ) units in CO2 adsorption, hydrogenation, and subsequent C–C coupling reaction to afford ethene. The achievements made in this work provide an alternative platform of metal-free nanocatalysts toward CO2-to-C2+ products via electroreduction by leveraging the highly porous, extensively conjugated, and aza-fused ring-abundant two-dimensional networks.