<i>In Situ</i> Conductance Monitoring of Electrochemical Reduced Graphene Oxide Film Formation on Microstructured Electrodes

Electrochemical reduction of graphene oxide (GO) is widely used to generate conductive reduced graphene oxide (rGO) films on microstructured electrodes, yet the evolution of electrical transport during the reduction process remains poorly understood. Here, we present a fully automated operando platform that enables time-resolved conductance monitoring during electrochemical GO reduction and correlates electrical transport with capacitive and structural changes. By integrating electrical two- and four-point measurements with impedance spectroscopy, we directly follow the emergence and in-plane expansion of electrochemically reduced GO domains. Raman spectroscopy identifies the reduction onset at approximately −0.6 V vs. Ag/AgCl, while operando measurements reveal potential-dependent growth kinetics and a strong correlation between conductance, capacitance, and film coalescence. Despite the intrinsic heterogeneity of drop-cast GO films, normalized conductance trajectories exhibit excellent reproducibility and reveal that the overpotential dictates the kinetic profile of rGO formation. The ability to directly resolve the emergence of rGO films and their formation kinetics provides a new level of process control for electrochemically fabricated rGO devices.