Tailoring Electrochemical Properties of PEDOT‐Based Platinum Electrode via Controlled Polymerization in Simulated Physiological Conditions

Abstract Optimizing the polymerization parameters of poly(3,4‐ethylenedioxythiophene) (PEDOT) is vital for enhancing neural electrode performance. This study systematically investigated the effects of 3,4‐ethylenedioxythiophene (EDOT) monomer concentration, the concentrations of dopants, including sodium polystyrene sulfonate (NaPSS) and lithium perchlorate (LiClO₄), and solvent choice (water vs. acetonitrile) on the electrochemical and morphological properties of PEDOT coatings on platinum (Pt) electrodes. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and current‐injection limit (CIL) measurements are used to evaluate performance, while scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM‐EDX) characterizes surface morphology. Results show that 0.01 m EDOT led to more uniform films and lower impedance compared to higher concentrations (0.03 to 0.05 m ). Among dopants, 2.5 mg mL⁻¹ NaPSS in water with 0.01 m EDOT achieved the lowest impedance (5 Ω cm 2 at 1 kHz) and significantly improved charge storage capacity (CSC) and CIL, approximately six and five times greater, respectively, than bare Pt electrodes. Electrodes prepared with 0.1 m LiClO₄ in acetonitrile at EDOT concentrations (0.03 to 0.05 m ) exhibited higher impedance than those using NaPSS. Optimized conditions, consisting of 0.01 m EDOT and 2.5 mg mL⁻¹ NaPSS in water, produced PEDOT film with the highest CSC and CIL values, while maintaining 94 and 96% of their impedance at 10 Hz and 1 kHz, respectively, over 24 h of continuous EIS cycling.