Abstract The inhibition performance and mechanism of nicotinic acid (NA), nicotinic acid amide (NAA) and 4-methoxypyridine (MP) for the corrosion of mild steel in 0.5 M HCl solution were investigated and compared by means of experimental tests, including potentiodynamic polarization and electrochemical impedance spectroscopy measurements, surface analyses and quantum chemistry calculation. The electrochemical results show that the inhibition efficiencies of the three inhibitors increase with the concentration and decrease with the temperature. The NAA and MP inhibitors exhibit the highest and lowest efficiency and activation energy for the corrosion process, respectively, which is confirmed by the corrosion morphology observation. Fourier transform infrared analysis and X-ray photoelectron spectroscopy (XPS) analysis confirm the spontaneous adsorption of all three inhibitors on the surface. The adsorption analysis demonstrates that the adsorption process follows Langmuir model and consists of both physisorption and chemisorption. The quantum chemistry calculation correlates the molecular structures and charge density distributions with the corrosion inhibition efficiencies of NAA, NA and MP inhibitors, and further proves that the good inhibition performance of NAA inhibitor originates its high adsorption ability.

中文翻译：

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烟酸衍生物作为盐酸溶液中低碳钢的缓蚀剂：实验和计算化学研究

摘要 通过动电位极化等实验测试比较了烟酸（NA）、烟酰胺（NAA）和4-甲氧基吡啶（MP）对低碳钢在0.5 M HCl溶液中腐蚀的抑制性能和机理。和电化学阻抗谱测量、表面分析和量子化学计算。电化学结果表明，三种抑制剂的缓蚀效率均随浓度升高而升高，随温度升高而降低。NAA 和 MP 抑制剂分别在腐蚀过程中表现出最高和最低的效率和活化能，这通过腐蚀形貌观察得到证实。傅里叶变换红外分析和 X 射线光电子能谱 (XPS) 分析证实了所有三种抑制剂在表面上的自发吸附。吸附分析表明吸附过程遵循朗缪尔模型，由物理吸附和化学吸附组成。量子化学计算将分子结构和电荷密度分布与NAA、NA和MP抑制剂的缓蚀效率相关联，进一步证明NAA缓蚀剂良好的缓蚀性能源于其高吸附能力。