Synthesis and Characterization of Polydopamine Coatings on Carbon Surfaces

Polydopamine (PDA) has emerged as a versatile material for surface modification, particularly in enhancing carbon-based electrodes used in electrochemical applications. In our study, we investigated the synthesis and deposition of PDA on carbon felt (CF) electrodes using two distinct methods: self-polymerization and hydrothermal synthesis using an autoclave. In the self-polymerization approach, dopamine (DA) monomers were spontaneously oxidized in a weak alkaline solution achieved by using Tris(hydroxymethyl)aminomethane (Tris), leading to uniform PDA coating on the CF. Conversely, the hydrothermal method involved the use of an autoclave to achieve controlled polymerization and deposition at elevated temperatures. The resulting PDA-coated electrodes were characterized using X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). These techniques provided insights into the atomic composition, chemical structure, and surface morphology of the modified electrodes. Our findings indicate that both methods result in the successful deposition of PDA, with notable differences in coating uniformity and thickness. The self-polymerization method produced a thinner, more homogeneous layer, while the hydrothermal synthesis led to a thicker, but slightly less uniform coating. These differences in coating characteristics have significant implications for the electrochemical performance of the electrodes. The PDA solutions were also tested by using Ultra Violet- Visible (UV-Vis) Spectroscopy and Hydrogen Nuclear Magnetic (H-NMR) Spectroscopy. These methods provided a better understanding of the polymerization process in the solution and an attempt to track the formation of the intermediates present in the polymerization process of DA into PDA was made. In conclusion, the choice of synthesis method influences the properties of PDA coatings on carbon substrates, which in turn affects their potential applications in fields such as energy storage, sensors, and catalysis. This study provides valuable insights for optimizing PDA deposition techniques to tailor carbon surfaces for specific electrochemical applications.