Facet-dependent dopamine electrochemistry at Pd-NPs/Tyr/Naf hybrid interfaces

Understanding how electrodeposition conditions govern the interplay between electrocatalytic and enzymatic pathways is crucial for the rational design of dopamine (DA)-sensitive electrochemical biosensors. Herein, a one-step electrodeposition approach was employed to fabricate Pd nanoparticles/tyrosinase/Nafion (Pd-NPs/Tyr/Naf) hybrid layers on screen-printed electrodes. Although the hybrid electrodes prepared at room temperature (20 ± 2 °C) and from an electrolyte pre-heated to 40 ± 5 °C exhibited comparable Pd loading and electroactive surface areas, they displayed distinct electrochemically active facet fingerprints corresponding to fundamentally different dominant crystallographic surface architectures. Consequently, the electrodes showed different redox behavior toward dopamine (DA), the substrate, and enzymatically generated quinone (Q), the reaction product. These findings demonstrate that electrodeposition provides an effective means to control facet populations in hybrid bioelectrocatalytic interfaces and establish a foundation for the development of biosensors with enhanced reaction-pathway selectivity.