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Electrochemical CO₂-to-Formate Conversion on Scalable Cu₃Sn Gas Diffusion Electrodes via an OCHO-Mediated Pathway

Lookup NU author(s): Dr Shahid RasulORCiD, Professor Mohamed MamloukORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

© 2026 The Authors. Published by American Chemical Society. Electrochemical CO2 reduction to formate (HCOO−) presents a sustainable strategy for carbon valorisation but remains challenging due to low selectivity and competing side reactions. In this work, we report a Cu3Sn gas diffusion electrode (GDE) synthesized via a scalable electrochemical spontaneous deposition (ESD) method, enabling highly selective CO2-to-formate conversion. The optimised CuSn35min electrode, corresponding to the Cu3Sn alloy phase, achieves a Faradaic efficiency of ∼90% for HCOO− at −0.85 V vs RHE in half-cell testing, while effectively suppressing hydrogen evolution and C2 product formation. Mechanistic and electrokinetic analyses, supported by in situ Raman spectroscopy, reveal a shift from *CO dimerization to an *OCHO-mediated pathway, driven by the synergistic interaction between Cu and Sn. Post-electrolysis structural characterization indicates the formation of surface SnO2 and Cu2O species on the Cu3Sn framework, suggesting a dynamically reconstructed alloy-oxide interface as the catalytically active phase. Full-cell evaluation in a Cu3Sn GDE∥Pt mesh configuration under continuous CO2 flow delivers ∼82% formate Faradaic efficiency and ∼73% energy efficiency at 180 mA cm−2, with formate Faradaic efficiency retained above 76% over 60 h of continuous operation. This work demonstrates a cost-effective and scalable route for designing alloy-based GDEs for efficient CO2 electroreduction.

Publication metadata

Author(s): Bellamkonda S, Rasul S, Mamlouk M

Publication type: Article

Publication status: Published

Journal: ACS Applied Energy Materials

Year: 2026

Volume: 9

Issue: 14

Pages: 9169-9180

Print publication date: 27/07/2026

Online publication date: 08/07/2026

Acceptance date: 16/06/2026

Date deposited: 10/08/2026

ISSN (electronic): 2574-0962

Publisher: American Chemical Society

URL: https://doi.org/10.1021/acsaem.6c00966

DOI: 10.1021/acsaem.6c00966

Data Access Statement: The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsaem.6c00966.

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