Ultrafine Cu nanoclusters confined within covalent organic frameworks for efficient electroreduction of CO2 to CH4 by synergistic strategy

Abstract

Electrocatalytic CO₂ reduction (ECR) to high value-added chemicals by using renewable electricity presents a promising strategy to realize “carbon neutrality”. However, the ECR system is still limited by its low current density and poor CO₂ utilization efficiency. Herein, by using the confinement effect of covalent organic frameworks (COFs) to confine the in-situ growth of metal nanoclusters (NCs), we develop a series of Cu NCs encapsulated on COF catalysts (Cu-NC@COF) for ECR. Among them, Cu-NC@CuPc-COF as a gas diffusion electrode (GDE) achieves a maximum CO₂-to-CH₄ Faradaic efficiency of 74 ​± ​3% (at −1.0 ​V vs. Reversible Hydrogen Electrode (RHE)) with a current density of 538 ​± ​31 ​mA ​cm⁻² (at −1.2 ​V vs. RHE) in a flow cell, making it one of the best among reported materials. More importantly, the current density is much higher than the relevant industrial current density (200 ​mA ​cm⁻²), indicating the potential for industrial application. This work opens up new possibilities for the design of ECR catalysts that utilize synergistic strategy.