Understanding electric fields at electrode/electrolyte interfaces strongly influences electrocatalytic processes, yet their characterization at high current densities is often hindered by gas evolution that interferes with physical and electromagnetic probes. Herein, a custom electrochemical flow cell is presented that suppresses bubble nucleation by directing a high-velocity jet of electrolyte toward the electrode surface through an internal nozzle. This enables in situ Raman spectroscopy and determination of electric field strengths at electrode/electrolyte interfaces under elevated current densities relevant to electrolysis and fuel cell applications. Video analysis shows that electrolyte flow reduces hydrogen bubble coverage on platinum (Pt) thin-film electrodes by85–88%. This enables stable Raman measurements at current densities up to 25 mA cm⁻², nearly two orders of magnitude higher than in a stagnant cell. Under reduced bubble coverage, graphene supported on Pt and gold (Au) electrodes exhibits Stark shifts in the graphene G-band corresponding to electric field strengths up to 10⁶ V cm⁻¹. The measurements reveal substrate-dependent behavior, including a ≈0.4 V shift in the graphene charge-neutrality point for Graphene/Pt relative to Graphene/Au. We propose a framework in which substrate work function, proton adsorption, and electrostatic gating collectively govern potential-dependent graphene doping and interfacial electric field strength at the electrode/electrolyte interface
Daniela A. Bushiri, Anvita Bansal, E. Saunders et al.· Journal of the Electrochemic...· 0 citations
Understanding electric fields at electrochemical interfaces is essential for optimizing electrocatalytic processes. However, their measurement under high current densities is limited by gas evolution, which obstructs access to the electrode surface. To address this, we developed a custom flow cell featuring an internal nozzle that directs fluid across the electrode surface. This high-velocity flow suppresses bubble nucleation by limiting local hydrogen supersaturation and thereby preserves optical access to the electrode. This design enables
in situ
Raman spectroscopy and direct quantification of interfacial electric fields under current densities relevant to electrolysis. High-speed optical imaging shows that bubble coverage decreases by 85–88% at 100 mL min⁻¹ relative to stagnant conditions. With this improvement, stable Raman measurements are possible at current densities up to 25 mA cm⁻², which is more than two orders of magnitude higher than in a non-flowing cell. Under these conditions, graphene-encapsulated Pt and Au electrodes exhibit Stark shifts in the graphene G-band. These shifts allow extraction of charge-carrier densities and local interfacial fields up to 3.8 × 10⁶ V cm⁻¹. Differences between graphene/Pt and graphene/Au highlight the substrate-dependent nature of the doping behavior. We propose a framework in which metal work function, proton adsorption, and electrostatic gating collectively determine the potential-dependent graphene doping and the resulting interfacial electric field.
Daniela A. Bushiri, Anvita Bansal, E. Saunders et al.· ECS Meeting Abstracts· 0 citations