Effects of Crystal Orientation on the Corrosion Behavior of Copper in Sodium Hydroxide Solution—Combined Experimental and Computational Density Functional Theory

During the material growth process, nanoscale clusters typically form first. Clusters can continuously adjust their internal atomic arrangement and ultimately evolving into crystal structure. The crystal structure exhibits different crystal orientations, which can lead to changes in the chemical activity and electronic structure of the metal surface, thereby influencing the interaction between metal and corrosive medium. This article thoroughly investigates the impact of crystal orientation on copper corrosion. It provides a foundation for understanding the role of nanoclusters in corrosion processes. The effects of crystal orientation on the corrosion behavior and mechanism of a single crystal copper in a 0.1 M NaOH solution were systematically investigated by conducting experiments and calculations on density functional theory (DFT). Both the electrochemical and calculation results showed that the crystal orientation had a significant effect on the corrosion resistance of Cu. In this study, a single crystal of copper with an exposed surface configuration of (100), (110), and (111) was taken as the research object. Electrochemical methods (potentiodynamic polarization and electrochemical impedance spectroscopy) were employed to investigate the corrosion behavior in a 0.1 M NaOH solution. Both impedance and corrosion current density values were in the following order: Cu(110) > Cu(100) > Cu(111), indicating that the corrosion resistance was in the same order. The density of state, surface energy, work function, and Mulliken charge were calculated through first-principles calculations with DFT to reveal the corrosion mechanism. The calculation results showed that the Mulliken charge distribution was closely related to the corrosion resistance. A higher value of Mulliken charge led to a greater number of electrons participating in the electrochemical reaction, which resulted in a poorer corrosion resistance. The sequence of Mulliken charge values on the first atom was (110) < (100) < (111), and in turn the corrosion resistance sequence was Cu(110) > Cu(100) > Cu(111). Employing simulation calculations in combination with experimental observations to interpret results and explore the corrosion mechanism is an effective research method. Once calculation models are established, they could be used to predict the corrosion behavior under different environmental conditions. Furthermore, it offers new directions for enhancing corrosion resistance by optimizing crystal orientation through studying the properties and behavior of nanoclusters.