Vertically Aligned Multiwalled Carbon Nanotube/Cu Catalysts for CO₂ Electroreduction

Abstract

Enhancing the selectivity of hydrocarbon products remains a key challenge to achieving artificial energy sustainability via closing the carbon cycle. While copper-based electrodes uniquely yield hydrocarbon products, the improvement of their product selectivity through physical morphology regulation shows great potential and requires further investigation. Here, we show the distinct morphological influences of the Cu electrode on the reaction selectivity. We synthesize binder-free, vertically aligned, nanoid forestlike copper electrocatalysts for superior improved methane conversion selectivity with respect to planar Cu. These Cu nanocomposites are fabricated through the conformal coating of vertically aligned multiwalled carbon nanotube array electrodes, which have matured to a cost-effective and scalable technology over the past two decades. Simulations reveal that carbon intermediates and protons can be confined in the gaps of the nanoid copper forest, which are formed in situ and in turn cover the catalytic sites and facilitate the simultaneous transfer of coupled electrons and protons. Such forest-like antenna morphology benefits from a threefold improvement of the CO 2 electroreduction performance through a decreased reaction onset potential, an increased current density, and enhanced hydrocarbon selectivity.

Electrocatalytic Upgrade of Impure CO2 by In Situ-Reconstructed Cu Catalysts with Gas Exsolution Electrolyzers

“…It is deserved to be mentioned that the in situ growth of copper particles on the highly conductive CF surface reduces the interfacial resistance and ensures higher electronic conductivity, ascribed to the close contact between the electrocatalyst Cu and CF achieved at the nanoscale. 2,48 Electrochemical impedance spectra for both Cu-CF and Cu-CuF electrodes have one semicircle (Figure S3); however, the diameter of the semicircle in the EIS spectra of Cu-CF is around 11.3 ohm•cm 2 , which is smaller than that of Cu-CuF (17.3 ohm•cm 2 ). This is attributed to the reduced interfacial resistance and higher electron and charge transfer of the Cu-CF electrode.…”