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以重氮化反应将对氨基化学修饰在石墨粉表面上并构建成碳糊电极。在此修饰电极上对-氨基酚表现处电化学催化氧化行为,与裸电极相比,氧化峰电位负移了73mV,氧化峰电流升高了60%。为了从分子水平上深入了解这种催化氧化行为,以38个碳构成的石墨烯片段-对氨基-对氨基酚组成的分子簇模型,MOPAC2012软件包内的PM6半经验分子轨道法研究了真空条件下体系的电化学催化活性。计算结果表明,所有建立的分子簇模型都是热力学稳定的,都具有负的反应吉布斯自由能。前线分子轨道的分析给出了电化学催化诱导下的电子转移过程,并定性地解释了对氨基酚在修饰和未修饰电极上的电化学氧化机理。对氨基酚在修饰电极上的可交换电子量比在未修饰电极上的大了64.8%。此结果恰好与试验结果中的氧化峰电流的升高结果一致;试验结果中的氧化还原峰电位对计算结果中的相应最高占有轨道和最低空轨道能呈现很好的线性关系。
The amino group was chemically modified on the surface of the graphite powder by diazotization to construct a carbon paste electrode. The electrochemical oxidation of p-aminophenol at the modified electrode showed a negative shift of 73mV and a 60% increase of oxidation peak current compared with the bare electrode. In order to deeply understand this catalytic oxidation behavior at the molecular level, a molecular cluster model consisting of a 38-carbon graphene-para-amino-p-aminophenol and a PM6 semi-empirical molecular orbital method in the MOPAC2012 software package were used to study the vacuum conditions Under the system of electrochemical catalytic activity. The calculated results show that all the molecular cluster models established are thermodynamically stable and both have negative Gibbs free energy. The analysis of frontier molecular orbitals gives the electron transfer process induced by electrochemical catalysis and qualitatively explains the electrochemical oxidation mechanism of p-aminophenol on both modified and unmodified electrodes. The amount of exchangeable electrons of p-aminophenol on the modified electrode was 64.8% larger than that on the unmodified electrode. The results are in good agreement with the results of the oxidation peak current. The results show that the redox potential shows a good linear relationship with the corresponding highest occupied orbit and lowest empty orbitals.