Process intensification of electrocatalytic CO2 reduction through pulsed electrochemistry

• Main Author: M Sivapaalan
• Other Authors: Lydia Helena Wong
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Science::Chemistry::Physical chemistry::Catalysis; Engineering::Materials
• Online Access: https://hdl.handle.net/10356/166460
• Institution: Nanyang Technological University

Of the many strategies available to close the carbon cycle, electrochemical carbon dioxide reduction (CO2RR) stands out as one of the more attractive methods as it can reduce CO2 emissions to the atmosphere whilst converting captured CO2 into high value-added multi-carbon (C2+) and single carbon products (C1¬) using renewable energy sources. The utilisation of copper-based catalysts improves the production of C2+ products due to their unique surface with the appropriate binding energy for CO* intermediates to produce C1 and C2+ products via C-C coupling. However, CO2RR being a multiple electron/proton transfer process, results in a large distribution of products and directly competes with the hydrogen evolution reaction (HER) in aqueous environments. The application of pulsed potentials as opposed to constant potentials on the working electrode have risen in popularity as a method to (1) suppress HER ; (2) increase product selectivity and (3) increase catalyst stability over extended reaction times. Cuprous oxide-derived copper catalysts, synthesised using hydrothermal synthesis, were tested in a H-cell set-up with the application of pulsed potentials and benchmarked against constant potential CO2RR. The catalyst’s surface conditions post-reaction were also studied using electrochemically active surface area (ECSA) measurements and material characterisation methods. Pulsed CO2RR on cuprous oxide-derived copper catalysts resulted in an improved selectivity towards C1 products rather than C2+ products when compared to constant voltage CO¬2RR and this result could be attributed to the surface reconstruction that occurs during the pulsed reaction. This suggests that surface roughness, coupled with many other factors, plays an important role in determining the product distribution and selectivity of CO2RR. This study demonstrates the abilities of pulsed CO2RR and its potential to be optimised for better product selectivity in the future.