Mechanistic Modeling of Electrochemical Gold Transfer from Gold Leaf to Screen-Printed Electrodes.

Electrochemical deposition of gold onto screen-printed electrodes (SPEs) typically relies on soluble gold precursors, which limits the scalability of low-cost, disposable sensing platforms. Here, we present a mechanistic modeling framework for solid-source electrochemical gold transfer, in which nanometric gold leaf (100-200 nm) serves as the precursor for electrodeposition. The process is described as a sequential system involving potentiostatic anodic dissolution of gold leaf, followed by electrodeposition onto carbon SPEs. The model integrates Butler-Volmer interfacial kinetics with diffusive transport of chloroaurate species, enabling quantitative analysis of how dissolution conditions govern the generation of electroactive species and subsequently control deposition behavior. Simulations reveal that the applied potential dictates the dissolution flux and resulting gold concentration, which directly determines the electrodeposition driving force. The gold transfer efficiency increases with deposition kinetics but exhibits a clear saturation behavior, indicating a transition from kinetically controlled to source-limited conditions. A dimensionless Damköhler-type analysis further demonstrates that system performance is governed by the interplay between reaction kinetics and mass transport, with a well-defined transition between kinetic and transport-limited regimes. This work establishes a predictive framework for solid-precursor electrochemical metal transfer and provides design guidelines for scalable, low-cost fabrication of gold-modified electrochemical sensors.