Modulating the surface interface of PTFE/Cu-based GDEs to boost the electrochemical conversion of CO2 to C2H4 at ultra-low overpotential
Venkata S.R.K. Tandava, Mayra S. Tovar-Oliva, Martí Biset‐Peiró, Diouldé Sylla, J.R. Morante, Ignacio Tudela, Sebastián Murcia‐López
Abstract
The electrochemical CO 2 reduction to multi-carbon products has received significant attention with the successful implementation of gas diffusion electrodes (GDEs) in flow electrolysers. In this work, we present the convenience of systematically modulating the surface interface of copper-based catalyst layers. Tailored GDEs fabricated by sputtering copper on polytetrafluoroethylene porous membranes and applying additive layers prove to be very effective in boosting selectivity towards C 2 H 4 and other C 2+ products. A comparative study of sputtered copper with additive layers (i.e. carbon black and/or catalyst-ionomer) allows to understand the role of the catalyst/catalyst-additive heterojunction. The additive layer aids not only in tuning the selectivity towards C 2 H 4 as the prime product, but also significantly lowers the cathodic overpotential required to achieve high current densities. PTFE/Cu GDE with an appropriate additive layer loading (i.e. mixed copper oxide in a carbon black matrix) converts CO 2 to C 2 H 4 with a faradaic efficiency of ≥ 70 % (combined faradaic efficiency of ≥90 % for C 2+ products) at industrially relevant current density of 250 mA·cm −2 with an iR -corrected potential of −0.55 V vs RHE. The PTFE/Cu/Cu x O-C GDE exhibits excellent stability, delivering a consistently high yield of C 2 H 4 over 25 h while effectively suppressing the competitive hydrogen evolution reaction. • PTFE/Cu-based GDEs for electrochemical CO 2 reduction have been developed. • Add-layers control the *CO/H 2 O ratio in the interface tuning the selectivity to C 2+ . • Combined Cu and Cu x O/C layers steer the selectivity to C 2 H 4 at low overpotentials. • Up-scaled electrode structures maintain the excellent performance.