Are Redox Catalytic Reaction Rates Accelerated in Microdroplets on Electrode Surfaces?

Lawrence, Nathan; Wadhawan, Jay

Abstract

Homogeneous redox catalysis within electrochemically supported microdroplets immobilised on an electrode surface, and bathed by an immiscible electrolyte solution is characterised using finite difference numerical methods, after conformal transformation of the physical problem. This is shown to be a challenging environment to simulate and model, not least due to the confinement of the heterogeneous electron transfer to the droplet/support/electrolyte boundary, and hence leading to acute convergent/divergent diffusion regimes. Reactivity at the triple phase boundary underpins both the spatial and temporal non-uniformity of the reacting droplet environment. Crucially, through comparison with experimental data reported in the literature, it is demonstrated that there is no droplet-induced acceleration of the redox catalytic reaction. Reasons for this discrepancy with literature are suggested. It is recommended that any inference of reaction rate acceleration through increased rate constants in microdroplets on surfaces be re-examined, lest the multi-dimensional dynamics at the three-phase boundary are unaccounted.

Citation

Lawrence, N., & Wadhawan, J. (online). Are Redox Catalytic Reaction Rates Accelerated in Microdroplets on Electrode Surfaces?. Journal of Solid State Electrochemistry, https://doi.org/10.1007/s10008-025-06283-4

• Journal Article Type: Article
• Acceptance Date: Mar 17, 2025
• Online Publication Date: Apr 12, 2025
• Deposit Date: Mar 17, 2025
• Publicly Available Date: Apr 14, 2025
• Print ISSN: 1432-8488
• Electronic ISSN: 1433-0768
• Publisher: Springer
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1007/s10008-025-06283-4
• Keywords: Microdroplets; Three-phase boundary; Redox catalysis; Reaction acceleration; Droplet voltammetry; Triple phase junction
• Public URL: https://hull-repository.worktribe.com/output/5084123