【作者】 刘勇；

【导师】 朱卫华；

【作者基本信息】 江苏大学 ， 化学， 2025， 硕士

【摘要】 近十年来新能源的发展极为迅速,无论是将电能直接储存或是转化为氢能进行储存都是当下的主要研究方向。在石油裂解制氢、天然气转化制氢以及电解水来制氢等诸多方法中,以电解水的方式更符合环境保护与新能源发展的趋势。作为电解中必不可少的一环,电极的研究十分广泛。随着分子导电性能测试技术的愈发成熟,更多有机分子的导电性质通过金电极得到研究。金电极同样在电解催化方面有着大量研究。在电解水的过程中选择合适的催化剂很重要,其中导电分子在电极表界面如何进行有效的电荷传输、催化位点的活性、基底的稳定性等都是主要影响因素。作为多功能分子的卟啉由于自身化学性质多用于催化领域,而卟啉在金电极表面功能化和性能改善的文章还较少。因此本文立足于单分子电子学和电化学催化的交叉领域,着重于金电极表界面分子的电荷传输以及电化学催化。本文从分子不同结构的导电性能中筛选良好的导电结构的角度,以及改善卟啉电荷传输性质、催化位点活性的角度和将卟啉在金电极表面形成亲水性的自组装分子膜（SAMs）等角度出发,探究了金电极在电荷传输和能量转换领域的不同应用。主要研究内容如下:（1）以4-甲硫基苯基作为锚定基团,通过脱水缩合制备了8种氨基酸连接的金属配位卟啉,通过“Au-S”键将其修饰至金电极的表面,使用还原解析的方法计算电极表面化合物的覆盖量。在酸性以及模拟海水环境中对比测试了不同个数的酰胺键、不同配位金属卟啉以及引入酰胺键的过程中氨基酸的手性对析氢性能的影响。发现随着酰胺键的增多,表界面的亲水性提高,与其他SAMs性能相比1d-SAM在0.5 M硫酸和模拟海水环境中塔菲尔斜率分别为111和228 m V/dec,表现出较好的析氢性能。对比氨基酸的手性,发现氨基酸的手性对析氢性能无显著影响。（2）通过以氨基酸与氨基卟啉进行脱水缩合完成一步酰胺化的同时引入亲水基和锚定基,合成了两种含硫氨基酸卟啉。以镍为配位金属,进一步研究了亲水性对催化剂析氢性能的影响。用还原解析法对金电极的表面化合物覆盖量进行计算。在酸性以及模拟海水中测试了析氢性能对比发现随着酰基的引入,催化剂的表界面亲水性得到提升,2a-SAM在0.5 M H₂SO₄环境和模拟海水环境中塔菲尔斜率分别为122和225 m V/dec,均低于2b-SAM的斜率,这表明引入酰基使析氢性能得到改善。同时催化剂在较宽的p H范围内表现出优良的普适性。（3）利用铃木偶联反应设计和制备了12种导电小分子。将设计的分子通过与金基底和金针之间形成MMM型（金属-分子-金属）的分子结,使用STM-BJ方法来测定分子的导电性质。由于测试需要,设计的这些分子都具有两个含硫基团。通过固定苯环为研究对象,改变含硫的锚定基团,对比了4-甲硫基苯基、2-噻吩基以及3-噻吩基作为锚定基团对分子电导性质的影响。同时通过固定对甲硫基苯基为锚定基团,改变芳香环结构,研究了苯环、蒽环、萘环及芘环的导电性能,以及通过改变分子的导电路径,研究分子的电导性质的变化。实验发现4-甲硫基苯基作为锚定基团更佳,以及以4-甲硫基苯基为锚定基团时苯环的导电性能比其他芳香环更好。此外发现同侧双取代的萘分子3-2d具有高达81.15 ns的π-π堆积产生电导值。随着分子导电路径变长,单分子的导电性能逐渐降低。更多还原

【Abstract】 In the past decade,the development of new energy has been extremely rapid,and whether it is direct storage of electric energy or conversion into hydrogen energy for storage is the main research direction at present.In various methods of hydrogen gas production,such as oil cracking,natural gas conversion,and water electrolysis.The way of water electrolysis is more in line with the trends of environmental protection and the development of new energy.As an indispensable part of electrolysis,the research on electrodes has been extensive.With the maturity of molecular conductivity testing technology,the conductivity properties of more organic molecules have been studied through gold electrodes.It has also been widely explored in the field of electrolytic catalysis.In this process,the selection of appropriate catalyst is very important.Among them,the effective charge transfer of conductive molecules at the electrode interface,the activity of catalytic sites,and the stability of the substrate are the main influencing factors.As a multifunctional molecule,porphyrins are widely utilized in the field of catalysis due to their chemical characteristics.However,there are relatively few studies on the functionalization and performance improvement of porphyrins on gold electrode surfaces.Therefore,this paper focuses on the intersection of single-molecule electronics and electrochemical catalysis,with particular emphasis on the charge transfer of molecules at the interface of gold electrodes and electrochemical catalysis.In this paper,the different applications of gold electrodes in the fields of charge transport and energy conversion from the perspectives of selecting good conductive structures from different molecular structures,the improvement of charge transfer properties of porphyrins,the activity of catalytic site,and the hydrophilicity of porphyrin self-assembled molecular films on the surface of electrode were discussed.The main research are as follows:（1）Eight kinds of amide-bonded metalloporphyrins were prepared with p-methylthiophenyl as the anchoring group by using dehydration condensation reaction.These porphyrins were modified and used as catalyst on the surface of the gold electrode via an"Au-S"bond,and the quantity of catalyst on the electrode surface was calculated by using the reduction desorption method.The effects of the numbers of amide bonds,the coordinated of different metalloporphyrins,and the chirality of amino acids during the introduction of amide bonds on the hydrogen evolution performance were tested in both acidic and simulated seawater environments.It was observed that as the number of amide bonds increased,the hydrophilicity at the interface increased.Compared with the performance of other SAMs,the Tafel slopes of 1d-SAM in acidc and simulated seawater environments were 111 and 228 m V/dec respectively,showing better hydrogen evolution performance.By comparing the chirality of amino acids,it was found that the chirality of amino acids had no significant effect on the hydrogen evolution performance.（2）On the basis of（1）,two sulfur-containing amide-bonded metalloporphyrins were synthesized via a one-step amidation process,involving dehydration condensation of amino acids and amino porphyrins,while incorporating both hydrophilic and anchoring groups.Nickel was used as the coordination metal,the influence of hydrophilic properties on hydrogen evolution performance of the catalyst was further investigated.The coverage of the catalyst on the gold electrode surface was calculated by using the reduction desorption method.The comparison of hydrogen evolution performance was tested in acidic and simulated seawater.It was found that with the introduction of acyl groups,the hydrophilicity of the surface and interface of the catalyst was improved.The Tafel slopes of 2a-SAM in the 0.5 M H₂SO₄ environment and the simulated seawater environment were 122 and 225 m V/dec respectively,both of which were lower than the slopes of 2b-SAM.This indicates that the introduction of acyl groups improves the hydrogen evolution performance.Meanwhile,the catalyst exhibits excellent universality within a wide p H range.（3）Twelve examples of conductive molecules were prepared by using the Suzuki coupling reaction.The designed molecule was used to form MMM（metal-molecule-metal）molecular junctions between gold substrates and gold needles,and the conductivity properties of the molecules were measured using the STM-BJ method.Due to the requirements of the test,each designed molecule contains two sulfur-containing groups.By fixing the benzene ring as the research object and changing the sulfur-containing anchoring group,the effects of using p-methylthiophenyl,2-thiophenyl and 3-thiophenyl as anchoring groups on the electrical conductivity of the molecules were compared.Additionally,the conductive properties of benzene,anthracene,naphthalene and pyrene rings were examined by fixing p-methylthiophenyl as the anchoring group and changing the structure of the aromatic ring.The experiment found that 4-methylthiophenyl is better as the anchoring group,and when 4-methylthiophenyl is used as the anchoring group,the electrical conductivity of the benzene ring is better than that of other aromatic rings.In addition,it was found that the ipsilateral disubstituted naphthalene molecules 3-2d had the highestπ-πstacking of81.15 ns,generating conductivity values.As the conductive path of molecules becomes longer,the conductive performance of single molecules gradually decreases.更多还原