A deeper understanding of the effect of chloride on the process of iron initial corrosion could reveal the detailed mechanism of the Cl^--induced acceleration corrosion of steel. In light of the difficulty to unravel the intricacies of H₂O-O₂-Cl^- interactions in experiments, this study conducted the molecular study on the effect of H₂O, O₂ and Cl^- coadsorption and interactions on the electrochemical corrosion process of Fe (100) surface by DFT method, and the electron-correlation functional is GGA-PW91. It is discovered that the adsorption of H₂O, O₂ and Cl^- all promote the electrochemical corrosion of iron. The electrochemical corrosion rate of iron surface rises as the Cl^-/H₂O concentration ratio increasing, while decrease with the Cl^-/O₂ concentration ratio increasing. The transition state search found that the presence of Cl^- assists the dissociation of H₂O on the iron surface, while the interaction between Cl^- and O₂ could be ignored. Moreover, the successive reaction of Cl^-, H₂O and O₂ with iron surface were further investigated. When the Cl^- reacts with H₂O ahead of O₂, the Cl^- promotes the iron oxidation via promoting the dissociation of H₂O. While O₂ and Cl^- firstly coadsorb on iron surface, Cl^- accelerates iron oxidation by exacerbating the iron surface losing electrons. These findings could facilitate the development of anti-corrosion techniques for steel in chloride environment.

中文翻译：

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H2O-O2-Cl- 吸附和反应对钢初始电化学腐蚀影响的分子见解


更深入地了解氯化物对铁初始腐蚀过程的影响可以^{揭示 Cl 诱导}钢加速腐蚀的详细机制。鉴于实验中难以解开 H₂O-O_2-Cl^- 相互作用的复杂性，本研究采用 DFT 方法对 H₂O、O₂ 和 Cl^- 共吸附和相互作用对 Fe （100） 表面电化学腐蚀过程的影响进行了分子研究，电子相关泛函为 GGA-PW91。研究发现，H₂O、O₂ 和 Cl^- 的吸附都促进了铁的电化学腐蚀。铁表面的电化学腐蚀速率随 Cl^-/H₂O 浓度比的增加而增加，而随着 Cl^-/O₂ 浓度比的增加而降低。过渡态搜索发现，Cl^- 的存在有助于 H₂O 在铁表面的解离，而 Cl^- 和 O₂ 之间的相互作用可以忽略不计。此外，进一步研究了 Cl^-、H₂O 和 O₂ 与铁表面的连续反应。当 Cl^- 在 O₂ 之前与 H₂O 反应时，Cl^- 通过促进 H₂O 的解离来促进铁氧化。O₂ 和 Cl^- 首先共吸附在铁表面，而 Cl^- 通过加剧铁表面失去电子来加速铁的氧化。这些发现有助于开发氯化物环境中钢的防腐技术。