Electrodeposited bismuth nanomaterials as binder free and scalable catalysts for highly selective CO2 to formate conversion
- 1Institute of Applied Physics, Vienna University of Technology 1040 Vienna Austria
- 2Indian Institute of Science Education and Research Pune 411008 India
- 3Department of Energy Conversion and Storage, Technical University of Denmark 2800 Lyngby Denmark
Abstract
The design of binder-free catalyst materials that can be manufactured in a scalable manner and utilized in gas diffusion electrodes (GDEs) remains a critical bottleneck for further advancement of CO2-to-formate electrolysis. Here, direct chronopotentiometric electrodeposition from a choline chloride:ethylene glycol deep eutectic solvent (DES) was applied to manufacture conformal, nanowire-like bismuth catalyst layers on commercial GDE substrates (Bi/GDE). These materials demonstrate a significantly improved catalytic activity per mass, compared with the conventional aqueous deposition method, as they showed uncompromised catalytic activity at a 6-times lower mass loading. Insight into the electrochemical surface restructuring mechanism was gained by combining ICP-MS dissolution analysis with in situ Raman spectroscopy. It could be shown that both DES and aqueous-derived catalysts undergo an identical Bi2O3 → Bi2O2CO3 → Bi0 restructuring sequence, converging to a common hierarchical nanoflower active phase morphology with equivalent charge-transfer resistance, demonstrating that the activated state, not the initial morphology, governs selectivity. Both catalysts deliver high formate faradaic efficiencies at 100 mA cm−2 (96.8% for the DES- and 93.7% for the aqueous-derived electrode), with the DES electrode achieving a mass-normalised activity for formate production of 166.9 mA mgBi−1. The electrodeposition process could be scaled to 150 cm2 substrates while maintaining a formate faradaic efficiency of 95.5%. Operation at 100 mA cm−2 is extended to 48 h of total elapsed time, corresponding to 32 h of cumulative electrolysis, through a periodic electrolysis swing protocol that mitigates GDE flooding, identified as the primary degradation pathway, while intrinsic catalyst stability showed no decline. This work establishes DES electrodeposition directly on GDEs as a material-efficient and inherently scalable route to high-performance Bi/GDE catalysts, and reveals electrochemical activation history as the key design parameter for CO2-to-formate conversion.
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BibTeX
@article{sihag2026electrodeposited,
title = {{Electrodeposited bismuth nanomaterials as binder free and scalable catalysts for highly selective CO2 to formate conversion}},
author = {Anil Kumar Sihag and Yashraj Kumar Singh and Esraa Kotob and Sarah Zulfa Khairunnisa and Markus Ostermann and Olga Guselnikova and Markus Valtiner and Maryam Abdinejad and Christian M. Pichler},
journal = {Journal of materials chemistry. A},
year = {2026},
month = oct,
doi = {10.1039/d6ta04799h},
url = {https://europepmc.org/article/PMC/PMC13720869},
note = {CC BY},
}
RIS
TY - JOUR
TI - Electrodeposited bismuth nanomaterials as binder free and scalable catalysts for highly selective CO2 to formate conversion
AU - Anil Kumar Sihag
AU - Yashraj Kumar Singh
AU - Esraa Kotob
AU - Sarah Zulfa Khairunnisa
AU - Markus Ostermann
AU - Olga Guselnikova
AU - Markus Valtiner
AU - Maryam Abdinejad
AU - Christian M. Pichler
PY - 2026
DA - 2026/10/12
JO - Journal of materials chemistry. A
DO - 10.1039/d6ta04799h
UR - https://europepmc.org/article/PMC/PMC13720869
AB - The design of binder-free catalyst materials that can be manufactured in a scalable manner and utilized in gas diffusion electrodes (GDEs) remains a critical bottleneck for further advancement of CO2-to-formate electrolysis. Here, direct chronopotentiometric electrodeposition from a choline chloride:ethylene glycol deep eutectic solvent (DES) was applied to manufacture conformal, nanowire-like bismuth catalyst layers on commercial GDE substrates (Bi/GDE). These materials demonstrate a significantly improved catalytic activity per mass, compared with the conventional aqueous deposition method, as they showed uncompromised catalytic activity at a 6-times lower mass loading. Insight into the electrochemical surface restructuring mechanism was gained by combining ICP-MS dissolution analysis with in situ Raman spectroscopy. It could be shown that both DES and aqueous-derived catalysts undergo an identical Bi2O3 → Bi2O2CO3 → Bi0 restructuring sequence, converging to a common hierarchical nanoflower active phase morphology with equivalent charge-transfer resistance, demonstrating that the activated state, not the initial morphology, governs selectivity. Both catalysts deliver high formate faradaic efficiencies at 100 mA cm−2 (96.8% for the DES- and 93.7% for the aqueous-derived electrode), with the DES electrode achieving a mass-normalised activity for formate production of 166.9 mA mgBi−1. The electrodeposition process could be scaled to 150 cm2 substrates while maintaining a formate faradaic efficiency of 95.5%. Operation at 100 mA cm−2 is extended to 48 h of total elapsed time, corresponding to 32 h of cumulative electrolysis, through a periodic electrolysis swing protocol that mitigates GDE flooding, identified as the primary degradation pathway, while intrinsic catalyst stability showed no decline. This work establishes DES electrodeposition directly on GDEs as a material-efficient and inherently scalable route to high-performance Bi/GDE catalysts, and reveals electrochemical activation history as the key design parameter for CO2-to-formate conversion.
SN - 2050-7488
SN - 2050-7496
ER -