Influence of surface pre-treatment and thermal annealing on the electrochemical and wettability behavior of copper

Abstract

This study investigates how different surface pre-treatments—acid etching, argon plasma exposure, and gold sputtering—combined with thermal annealing affect the wettability and electrochemical behavior of high-purity copper. Contact angle measurements showed a clear transition from hydrophobic copper (97°) to highly hydrophilic surfaces (down to 7.1°) after oxidation. Plasma-treated surfaces showed variable wettability depending on treatment time and gas flow, ranging from hydrophobic to moderately hydrophilic. Cyclic voltammetry and electrochemical impedance spectroscopy confirmed that these surface modifications changed redox activity and charge transfer resistance, mainly due to altered surface oxide structure and energy levels. Thermal annealing further influenced the oxide growth, making it more uniform and stable, which in turn affected the electrochemical response. Such thermal treatment after surface modification helped to stabilize the oxide layer and tune its electronic properties. These combined effects suggest that a proper sequence of surface pre-treatment and annealing can be used to control the copper surface for better performance in electrochemical systems. This may be useful for applications in sensing, catalysis, or corrosion protection, where both wetting properties and electrochemical stability are critical. The results highlight the importance of understanding how surface oxide properties, wettability, and charge transfer processes are linked, and how they can be engineered in a controlled way. Further work is needed to study the long-term durability and repeatability of these modified copper surfaces under practical conditions.