硫化钴—石墨烯复合对电极及其光电性能研究

发布时间：2018-12-06 18:59

【摘要】：染料敏化太阳能电池(Dye-sensitized solar cell, DSSC)由于具有不错的能量转化效率、制造成本低、环境友好等优点，成为非常有吸引力的新一代太阳能电池。对电极是DSSC非常重要的组件之一，Pt是目前为止最常用的对电极材料。然而，Pt是贵金属，且资源有限，使用Pt对电极大大增加了DSSC的成本。因此，开发不含Pt且具有较高效率的对电极材料代替传统Pt电极具有重要意义。由于CoS具有优异的电催化性能、原材料丰富且成本低，，石墨烯具有卓越的导电性、快速的电荷迁移率、高的比表面积及良好的化学和热稳定性，在本文中，我们制备了硫化钴-石墨烯复合对电极，并从以下几个方面进行了研究： (1)通过水热法制备CoS粉体，与石墨烯混合，加入有机粘结剂CMC-Na形成均匀的浆料，采用刮刀法将浆料印刷到FTO玻璃基底上，通过控制浆料中CoS和石墨烯的比例，制备出不同配比的CoS-石墨烯复合对电极； (2)使用XRD、FSEM和EDS表征复合对电极的结构和形貌，结果表明，水热法制备的CoS粉体为六角结构，尺寸约为500nm，大颗粒是由几十纳米的小颗粒聚集而成的。制备的复合对电极，CoS颗粒均匀的分布在对电极薄膜中，石墨烯为片层卷曲结构，不同配比复合对电极薄膜的厚度都控制在13~15μm，且各元素在其中的分布较为均匀； (3)采用CV法测量复合对电极的电催化活性及长期稳定性，结果表明，CoS具有优异的电催化活性，而石墨烯的电催化性能较差。当在石墨烯中加入CoS后，复合对电极的电催化活性显著提高，CoS-石墨烯复合对电极的电催化活性比Pt对电极高，长期稳定性与Pt一样好； (4)采用I-V曲线和EIS表征DSSC的光电性能，结果表明，CoS和石墨烯具有很好的协同效应，复合后，电荷转移阻抗和Nernst扩散阻抗均减小，硫化钴-石墨烯复合对电极DSSC的能量转化效率比硫化钴和石墨烯单独作为对电极时DSSC的能量转化效率高； (5)研究CoS和石墨烯的最佳配比，随着CoS比例的增加，短路电流和填充因子均呈现先增大后减小的趋势。当复合对电极中，CoS的质量比为40%，石墨烯的质量比为60%时，具有最佳的能量转化效率，为6.31%，高于以CoS和石墨烯单独作为DSSC对电极时的效率，分别为3.51%和4.26%，甚至高于以传统Pt作为DSSC对电极的效率，为5.98%。
[Abstract]:Dye-sensitized solar cells (Dye-sensitized solar cell, DSSC) have become an attractive new generation of solar cells due to their good energy conversion efficiency, low manufacturing cost and environmental friendliness. Counter electrode is one of the most important components of DSSC. Pt is the most commonly used counter electrode material so far. However, Pt is a precious metal with limited resources. The use of Pt pair electrodes greatly increases the cost of DSSC. Therefore, it is of great significance to develop Pt free and efficient electrode materials instead of traditional Pt electrodes. Because of its excellent electrocatalytic properties, abundant raw materials and low cost, graphene has excellent electrical conductivity, fast charge mobility, high specific surface area and good chemical and thermal stability. Cobalt-graphene sulphide composite electrode was prepared and studied in the following aspects: (1) CoS powder was prepared by hydrothermal method, mixed with graphene, and organic binder CMC-Na was added to form uniform slurry. The slurry was printed on the FTO glass substrate by scraper method. By controlling the ratio of CoS and graphene in the slurry, the CoS- graphene composite counter electrode with different ratio was prepared. (2) XRD,FSEM and EDS were used to characterize the structure and morphology of the composite opposite electrode. The results showed that the CoS powder prepared by hydrothermal method was hexagonal structure with a size of about 500 nm, and the large particles were composed of dozens of nanometers and small particles. The CoS particles are uniformly distributed in the counter electrode film, and graphene is the crimp structure of the lamellar layer. The thickness of the composite counter electrode film is controlled at 1315 渭 m, and the distribution of the elements in the film is more uniform. (3) the electrocatalytic activity and long-term stability of composite electrode were measured by CV method. The results showed that CoS had excellent electrocatalytic activity, but graphene had poor electrocatalytic activity. When CoS was added into graphene, the electrocatalytic activity of the composite electrode increased significantly. The electrocatalytic activity of the CoS- graphene composite electrode was higher than that of the Pt electrode, and the long-term stability of the composite electrode was as good as that of Pt. (4) the photoelectric properties of DSSC were characterized by I-V curve and EIS. The results show that CoS and graphene have good synergistic effect, and the charge transfer impedance and Nernst diffusion impedance decrease after recombination. The energy conversion efficiency of cobalt sulphide / graphene composite to DSSC is higher than that of DSSC when cobalt sulphide and graphene are used as counter electrodes alone. (5) the optimum ratio of CoS and graphene is studied. With the increase of CoS ratio, the short-circuit current and filling factor increase first and then decrease. When the mass ratio of CoS and graphene is 40 and 60, the optimum energy conversion efficiency is 6.31, which is higher than that when CoS and graphene are used as DSSC pair electrodes alone. It was 3.51% and 4.26% respectively, which was even higher than that of traditional Pt as DSSC electrode, 5.98%.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM914.4

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