Use of Chitosan as Copper Binder in the Continuous Electrochemical Reduction of CO2 to Ethylene in Alkaline Medium

Aitor Marcos-Madrazo; Clara Casado-Coterillo; Jesús Iniesta; Angel Irabien

doi:10.3390/membranes12080783

Use of Chitosan as Copper Binder in the Continuous Electrochemical Reduction of CO₂ to Ethylene in Alkaline Medium

Membranes (Basel). 2022 Aug 15;12(8):783. doi: 10.3390/membranes12080783.

Authors

Aitor Marcos-Madrazo¹, Clara Casado-Coterillo¹, Jesús Iniesta², Angel Irabien¹

Affiliations

¹ Department of Chemical and Biomolecular Engineering, Universidad de Cantabria, Av. Los Castros s/n, 39005 Santander, Spain.
² Department of Physical Chemistry, Institute of Electrochemistry, Universidad de Alicante, Av. Raspeig s/n, 03080 Alicante, Spain.

Abstract

This work explores the potential of novel renewable materials in electrode fabrication for the electrochemical conversion of carbon dioxide (CO₂) to ethylene in alkaline media. In this regard, the use of the renewable chitosan (CS) biopolymer as ion-exchange binder of the copper (Cu) electrocatalyst nanoparticles (NPs) is compared with commercial anion-exchange binders Sustainion and Fumion on the fabrication of gas diffusion electrodes (GDEs) for the electrochemical reduction of carbon dioxide (CO₂R) in an alkaline medium. They were tested in membrane electrode assemblies (MEAs), where selectivity to ethylene (C₂H₄) increased when using the Cu:CS GDE compared to the Cu:Sustainion and Cu:Fumion GDEs, respectively, with a Faradaic efficiency (FE) of 93.7% at 10 mA cm^-2 and a cell potential of -1.9 V, with a C₂H₄ production rate of 420 µmol m^-2 s^-1 for the Cu:CS GDE. Upon increasing current density to 90 mA cm^-2, however, the production rate of the Cu:CS GDE rose to 509 µmol/m²s but the FE dropped to 69% due to increasing hydrogen evolution reaction (HER) competition. The control of mass transport limitations by tuning up the membrane overlayer properties in membrane coated electrodes (MCE) prepared by coating a CS-based membrane over the Cu:CS GDE enhanced its selectivity to C₂H₄ to a FE of 98% at 10 mA cm^-2 with negligible competing HER. The concentration of carbon monoxide was below the experimental detection limit irrespective of the current density, with no CO₂ crossover to the anodic compartment. This study suggests there may be potential in sustainable alernatives to fossil-based or perfluorinated materials in ion-exchange membrane and electrode fabrication, which constitute a step forward towards decarbonization in the circular economy perspective.

Keywords: CO2 electro reduction; alkaline medium; chitosan; copper; ethylene production.

Grants and funding

This research was funded by the Spanish Ministry for Science and Innovation, grant numbers PID2019-108136RB-C31, PID2019-108136RB-C32, PID2020-112845RB-I00 and EIN2020-112319. A.M.M. also acknowledges the Ministry for the Early Stage researcher contract (FPI grant no. BES-2017-080795).