Integration of ultrafine CuO nanoparticles with two-dimensional MOFs for enhanced electrochemical CO2 reduction to ethylene

Abstract

To facilitate the electrochemical CO2 reduction (ECR) to fuels and valuable chemicals, the development of active, low cost, and selective catalysts is crucial. We report a novel ECR catalyst consisting of CuO nanoparticles with sizes ranging from 1.4 to 3.3 nm anchored on Cu metal-organic framework (Cu-MOF) nanosheets obtained through a one-step facile solvothermal method. The nanocomposites provide multiple sites for efficient ambient ECR, delivering an average C2H4 faradaic efficiency (FE) of ~50.0% at –1.1 V (referred to the reversible hydrogen electrode) in 0.1 mol/L aqueous KHCO3 using a two-compartment cell, in stark contrast to a C2H4 FE of 25.5% and 37.6% over individual CuO and Cu-MOF respectively, also surpassing most newly reported Cu-based materials under similar cathodic voltages. The C2H4 FE remains at over 45.0% even after 10.0 h of successive polarization. Also, a ~7.0 mA cm−2 C2H4 partial geometric current density and 27.7% half-cell C2H4 power conversion efficiency are achieved. The good electrocatalytic performance can be attributed to the interface between CuO and Cu-MOF, with accessible metallic moieties and the unique two-dimensional structure of the Cu-MOF enhancing the adsorption and activation of CO2 molecules. This finding offers a simple avenue to upgrading CO2 to value-added hydrocarbons by rational design of MOF-based composites.