基于量子化学计算优化的氮掺杂碳量子点缓蚀剂制备及其缓蚀性能

Preparation and corrosion performance of nitrogen-doped carbon quantum dots as corrosion inhibitors based on quantum chemical calculation

[目的]氮掺杂碳量子点(N-CQDs)作为一种绿色高效的新型缓蚀剂,在腐蚀控制领域具有巨大的应用潜力。但由于其结构无法精确调控,很难对制备N-CQDs的众多前驱体进行筛选。[方法]依据密度泛函理论(DFT),通过Fukui指数计算各前驱体分子的优先反应活性位点,确定前驱体分子间一步脱水缩合反应产物的分子结构,并进行全局参量和局部参量的计算,分析了采用柠檬酸分别与乙二胺、尿素和氨基胍盐酸盐作为前驱体所合成的3种N-CQDs的缓蚀性能,再通过称重法对水热法合成的3种N-CQDs的缓蚀性能进行验证,优选出缓蚀性能最佳的缓蚀剂。采用紫外可见吸收光谱、荧光光谱和高分辨率场发射透射电镜表征优选缓蚀剂的荧光性能和表面形貌,并以电化学方法和表面分析方法研究此缓蚀剂对Q235碳钢在0.5 mol/L硫酸溶液中的缓蚀机理。[结果]以柠檬酸和氨基胍盐酸盐为前驱体制备的N-CQDs-3缓蚀性能最佳,且试验结果和理论计算结果一致。N-CQDs-3在紫外激发光下显示蓝绿光,平均粒径为(2.5±0.8)nm。该缓蚀剂是一种混合型缓蚀剂,主要通过物理和化学吸附同时抑制金属在酸溶液中腐蚀反应的发生,其对Q235碳钢在0.5 mol/L硫酸溶液中的缓蚀效率最高可达95.3%。[结论]通过量子化学计算方法对制备N-CQDs所用的前驱体进行筛选,提前预测其缓蚀性能,可提高试验效率。

[Introduction]Nitrogen-doped carbon quantum dots(N-CQDs),as a novel type of green and efficient corrosion inhibitor,have great potential for application in the field of corrosion control.However,due to the inability to precisely regulate its structure,it is difficult to screen numerous precursors for the preparation of N-CQDs.[Method]Based on density functional theory(DFT),the priority reaction active sites of each precursor molecule were calculated using the Fukui index to determine the molecular structure of the reaction product of one-step dehydration condensation between precursor molecules.Global and local parameters were calculated,and the corrosion inhibition performance of three N-CQDs synthesized using citric acid with ethylenediamine,urea,and aminoguanidine hydrochloride,respectively,as precursors was analyzed.Further verification of the corrosion inhibition performance of the three N-CQDs synthesized by hydrothermal method was carried out through weight loss method,and the N-CQDs with the best corrosion inhibition performance was selected.The fluorescence emission property and surface morphology of the best corrosion inhibitor were characterized by ultraviolet-visible(UV-vis)absorption spectroscopy,fluorescence spectroscopy,and high-resolution field emission transmission electron microscopy(HRTEM).The corrosion inhibition mechanism of this inhibitor on Q235 carbon steel in 0.5 mol/L sulfuric acid solution was studied by electrochemical method and surface analysis techniques.[Result]The results showed that N-CQDs-3 prepared with citric acid and aminoguanidine hydrochloride as precursors had the best corrosion inhibition performance,and the experimental results were consistent with the theoretical calculations.N-CQDs-3 exhibits blue-green light under ultraviolet excitation,with an average particle size of(2.5±0.8)nm.It is a mixed-type inhibitor that mainly inhibits the occurrence of metal corrosion reactions in acid solutions through physical and chemical adsorption.Its corrosion inhibition efficiency for Q235 carbon steel reached up to 95.3%in 0.5 mol/L sulfuric acid solution.[Conclusion]By using quantum chemical calculation methods to screen the precursors used in the preparation of N-CQDs and predict their corrosion inhibition performance in advance,the experimental efficiency can be improved.