School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
J Chem Phys. 2011 Jun 21;134(23):234706. doi: 10.1063/1.3599090.
Corrosion is a fundamental problem in electrochemistry and represents a mode of failure of technologically important materials. Understanding the basic mechanism of aqueous corrosion of metals such as Cu in presence of halide ions is hence essential. Using molecular dynamics simulations incorporating reactive force-field (ReaxFF), the interaction of copper substrates and chlorine under aqueous conditions has been investigated. These simulations incorporate effects of proton transfer in the aqueous media and are suitable for modeling the bond formation and bond breakage phenomenon that is associated with complex aqueous corrosion phenomena. Systematic investigation of the corrosion process has been carried out by simulating different chlorine concentration and solution states. The structural and morphological differences associated with metal dissolution in the presence of chloride ions are evaluated using dynamical correlation functions. The simulated atomic trajectories are used to analyze the charged states, molecular structure and ion density distribution which are utilized to understand the atomic scale mechanism of corrosion of copper substrates under aqueous conditions. Increased concentration of chlorine and higher ambient temperature were found to expedite the corrosion of copper. In order to study the effect of solution states on the corrosion resistance of Cu, partial fractions of proton or hydroxide in water were configured, and higher corrosion rate at partial fraction hydroxide environment was observed. When the Cl(-) concentration is low, oxygen or hydroxide ion adsorption onto Cu surface has been confirmed in partial fraction hydroxide environment. Our study provides new atomic scale insights into the early stages of aqueous corrosion of metals such as copper.
腐蚀是电化学中的一个基本问题，也是技术上重要材料失效的一种模式。因此，理解在卤素离子存在下金属（如 Cu）的水相腐蚀的基本机制是至关重要的。本研究采用包含反应力场（ReaxFF）的分子动力学模拟，研究了铜基底与水中氯的相互作用。这些模拟纳入了水相质子转移的影响，适用于模拟与复杂水相腐蚀现象相关的键形成和键断裂现象。通过模拟不同的氯浓度和溶液状态，对腐蚀过程进行了系统的研究。利用动力学相关函数评估了在氯离子存在下金属溶解相关的结构和形态差异。通过分析原子轨迹，我们对电荷状态、分子结构和离子密度分布进行了研究，以了解水相条件下铜基底腐蚀的原子尺度机制。研究发现，较高的氯浓度和环境温度会加速铜的腐蚀。为了研究溶液状态对 Cu 耐腐蚀性的影响，我们配置了水中质子或氢氧根的部分分数，并观察到在氢氧根环境下的腐蚀速率更高。当 Cl(-)浓度较低时，在部分分数氢氧根环境下已经证实了氧或氢氧根离子在 Cu 表面的吸附。本研究为金属（如铜）的水相腐蚀的早期阶段提供了新的原子尺度见解。
