基于氮化碳光电材料构建及其光电性能研究

发布时间：2019-05-29 00:56

【摘要】：在大力提倡发展社会经济,更新科学技术的时代下,能源危机和生态环境污染问题始终是人们不可避免的两大难题。光电化学研究在实现高效率光电转换,改善能源危机和解决环境污染等难题方面贡献巨大。氮化碳作为一类具有优异的热稳定性和化学稳定性的新型半导体材料,在光催化降解污染物,光催化分解水制氢和电催化氧还原等领域有广泛应用。然而,因其比表面积小、活性位点少、光利用率不高难以发挥其在光电化学领域的重要作用。因此,对氮化碳材料进行改性以改善其光电化学性能尤为重要。本文主要设计在氮化碳表面负载金属,期望通过引入金属增强氮化碳的光电化学性能,并且经过一系列的表征测试分析,如XRD、XPS、PL等手段探讨了金属对氮化碳光电性能的影响,以及成功构建检测酚类及抗生素的光电化学传感器。本论文首先选择了三种不同制备方法合成的氮化碳材料,即以二氰二胺为原料,通过两步煅烧法热聚合制备氮化碳BCN;在此基础上将其通过强酸(盐酸)室温搅拌处理得到质子化氮化碳CNH;最后将三聚氯氰(cyanuric chloride)、三聚氰胺(melamine)在溶剂热条件下合成氮化碳GCN,并对上述三种氮化碳进行光电性能的考察。经过对三种氮化碳材料进行光电流测试,结果表明,CNH光生电流响应能力最强,说明CNH材料内部电子与空穴对的分离速率均高于其他两种氮化碳(BCN,GCN),其光电化学性能优于BCN,GCN材料。而且,在加入相同浓度的酚类有害物质4-氯苯酚(4-CP)后,CNH材料的光生电流响应增幅最大。因此,构建了基于CNH检测4-CP的光电化学传感器,CNH检测4-CP的线性范围是6.1-13.5μM,检测限为2.1μM。其次,设计将金属与CNH材料进行复合以进一步调控氮化碳的光电化学性能。选用传统的柠檬酸三钠化学还原氯金酸(HAuCl4·4H2O)的方法,在CNH表面上负载金属Au。经过表征分析得出,Au是以Au单质(Au0)的形式均匀分布在CNH的表面。经过质子化的CNH表面有大量的H+,可定向的与AuCl4-结合,提高Au单质在CNH表面的分散性。Au的引入大幅度提高CNH的光吸收能力和扩宽光响应范围。通过光电流测试结果表明,10 wt%Au/CNH具有最佳光电化学性能。由于Au的等离子体(SPR)效应能诱导氮化碳CNH内部导带上的电子快速迁移至电极表面,能有效分离电子-空穴对,促进光生电流的增强。因此,Au的引入大幅提高CNH的光电化学性能。另外将Au/CNH复合纳米光电材料构建检测4-CP的光电化学传感器,相比单体CNH材料,Au/CNH能高效灵敏检测4-CP,检测限低至0.08μM。最后,通过铜基离子液体([C_(16)mim]_2CuCl_4)辅助溶剂热法,在GCN的表面原位引入金属Cu,并考察Cu的引入对GCN光电性能的影响。紫外-可见漫反射(DRS)光谱和光致发光光谱(PL)表征结果表明,Cu/GCN复合纳米光电材料其光吸收范围明显扩宽,且发光强度远低于GCN材料,表明Cu/GCN复合材料的电子-空穴复合率大幅降低,表现出优异的光化学性能。而且对其进行光电流测试发现,经Cu改性后的GCN材料,由于Cu优异的捕获电子和导电子能力,使Cu/GCN电子-空穴对的分离速率增强,从而提高光电流响应。而且,5 wt%Cu/GCN表现出最优的光电化学性能。同样的,将5 wt%Cu/GCN构建光电化学传感器测试对BPA的光电检测性能,其检测下限低至0.012μM。因此,将金属与氮化碳材料进行复合,不仅大幅度提高光电化学响应信号,而且对构建光电化学传感器检测酚类及抗生素等一些有害物质具有实际性的指导意义。
[Abstract]:In the era of vigorously promoting the development of the social economy and updating the science and technology, the energy crisis and the ecological environmental pollution have always been the two main problems that people are inevitable. Photoelectrochemical research has made great contributions to the problems of high efficiency photoelectric conversion, energy crisis and environmental pollution. As a new type of semiconductor material with excellent thermal stability and chemical stability, carbon nitride is widely used in the fields of photocatalytic degradation of pollutants, photocatalytic decomposition of water, and electrocatalytic oxygen reduction. However, because of its small specific surface area, less active site and low light utilization rate, it is difficult to exert its important role in the field of photochemistry. Therefore, it is particularly important to modify the carbon nitride material to improve the photoelectric chemical properties thereof. This paper is mainly designed on the surface of carbon nitride, and it is expected to enhance the photoelectrochemical performance of the carbon nitride by introducing the metal, and through a series of characterization test and analysis, such as XRD, XPS and PL, the effect of the metal on the photoelectric properties of the carbon nitride is discussed. And successfully constructing a photoelectric chemical sensor for detecting the phenols and the antibiotics. In this paper, three kinds of carbon nitride materials, which are synthesized by three different preparation methods, are selected as raw materials, and the carbon nitride BCN is prepared by the thermal polymerization of the two-step two-step sintering method, and the protonated carbon nitride CNH is obtained by stirring at room temperature with strong acid (hydrochloric acid) at room temperature. Finally, cyanuric chloride (cyanuric chloride) and melamine (Melamine) were synthesized into carbon nitride (GCN) under the condition of solvent, and the photoelectric properties of the three kinds of carbon nitride were investigated. The photo-current test of three carbon nitride materials shows that the response capability of CNH is the strongest, and the separation rate of the electron and hole pairs in the CNH material is higher than that of the other two kinds of carbon nitride (BCN, GCN), and the photoelectrochemical performance is better than that of the BCN and GCN materials. Moreover, after the addition of 4-chlorophenol (4-CP) with the same concentration of phenol, the photo-generated current response of the CNH material is the largest. Therefore, a photoelectric chemical sensor based on CNH for 4-CP is constructed. The linear range of the CNH detection 4-CP is 6.1-13.5. m u.M, and the detection limit is 2.1. m u.M. Secondly, the metal is combined with the CNH material to further control the photoelectrochemical performance of the carbon nitride. The traditional method for the chemical reduction of chloroauric acid (HAuCl4 路 4H2O) by trisodium citrate is used to load the metal Au on the surface of the CNH. It is found that Au is uniformly distributed on the surface of CNH in the form of Au (Au0). The protonated CNH surface has a large number of H +, orientable and AuCl4-binding, and the dispersion of the simple substance on the surface of the CNH is improved. The introduction of Au greatly improves the light absorption capacity and the light response range of CNH. The results of photocurrent test show that 10 wt% Au/ CNH has the best photoelectrochemical performance. Since the plasma (SPR) effect of Au can induce the rapid migration of electrons on the conduction band of the carbon CNH to the surface of the electrode, the electron-hole pair can be effectively separated, and the enhancement of the photo-generated current can be promoted. Therefore, the introduction of Au greatly improves the photoelectrochemical performance of the CNH. in addition, the Au/ CNH composite nanometer photoelectric material is used for constructing a photoelectric chemical sensor for detecting 4-CP, compared with the monomer CNH material, the Au/ CNH can efficiently and sensitively detect the 4-CP, and the detection limit is low to 0.08. mu; M; and finally, the metal Cu is introduced in situ on the surface of the GCN by a copper-based ionic liquid ([C _ (16) mim] _ 2CuCl _ 4) as the auxiliary solvothermal method, The influence of the introduction of Cu on the photoelectric properties of the GCN is also investigated. The results of ultraviolet-visible diffuse reflection (DRS) and photoluminescence (PL) show that the light absorption range of the Cu/ GCN composite nano-electro-optical material is obviously widened, and the luminescence intensity is much lower than that of the GCN material, indicating that the electron-hole recombination rate of the Cu/ GCN composite material is greatly reduced, Showing excellent photochemical properties. It was found that after Cu-modified GCN material, the separation rate of Cu/ GCN electron-hole pair was enhanced, and the photocurrent response was improved. Furthermore, the 5 wt% Cu/ GCN exhibited the optimum photoelectrochemical performance. In the same way, the photoelectric detection performance of the photoelectric chemical sensor test on the BPA is constructed by the 5 wt% Cu/ GCN, the lower limit of the detection is as low as 0.012. m u.M, therefore, the metal and the carbon nitride material are compounded, so that the photoelectric chemical response signal is greatly improved, But also has the guiding significance for building a photoelectric chemical sensor to detect some harmful substances such as phenols and antibiotics.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657

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