【作者】 吴德智；

【导师】 范希梅；

【作者基本信息】 西南交通大学 ， 材料科学与工程， 2012， 硕士

【摘要】 半导体光催化技术,由于其具有“节能”和“环保”的双重意义,因此已经在污水的处理、抑菌杀菌以及环境的净化等领域得到广泛的研究与应用。然而,在半导体光催化剂的研究中,涉及到的多数是宽禁带的半导体材料,如ZnO, TiO2, SnO2等等,这些半导体材料由于本身具有大的带隙能,因此它们对太阳光能的利用率并不高,而且由于光生电子与空穴的复合特性,使单一的半导体光催化剂在开发利用方面受到了限制。因此需要对单一的半导体光催化剂进行改性处理,以达到提高半导体光催化活性的目的。硫化亚铜(Cu2S)是一种窄禁带(乓=1.2-1.24eV)的p型半导体材料,具有良好的化学和热稳定性能,是一种良好的光电材料,在太阳光能利用等领域有着巨大的应用潜能。本论文以纳米Cu2S及其复合材料作为研究对象。采用多元醇法制备样品并通过XRD, FESEM, EDS, XPS, FTIR和UV-Vis DRS的表征方法对样品进行表征,并研究不同因素对样品的结构、形貌以及光催化活性的影响。论文的研究工作分为以下三个部分：1.采用高温多元醇法,以醋酸铜为铜源,一缩二乙二醇(DEG)为溶剂和还原剂,通过改变合成条件,制备出不同结构和形貌的Cu2S纳米材料,并分析不同结构和形貌对样品光催化性能的影响。实验结果表明,当Cu/S摩尔比为1：1.5和1：1时,样品的XRD中出现了CuS的杂质峰；然而,当增大Cu/S摩尔比时,样品的XRD图谱中只存在Cu2S的衍射峰。此外,样品对甲基橙溶液都表现出一定的光催化降解能力。当Cu/S摩尔比为2：1时,样品的平均晶粒尺寸随着体系反应温度的增加而增大,因此样品的光催化性能有所下降。综合样品的结构和形貌,当Cu/S摩尔比为2：1,在反应温度为180℃的条件下,样品的光催化性能最佳。2.以多壁碳纳米管(MWCNTs)为载体,醋酸铜为铜源,聚乙烯毗咯烷酮(PVP)为表面活性剂,采用多元醇法制备Cu2S/MWCNTs纳米复合材料,并研究不同的铜源含量以及不同的PVP含量对样品的结构、形貌以及光催化性能的影响。当铜源含量较小时,负载在MWCNTs管壁上的Cu2S纳米颗粒大小均匀、分散效果较好,因而样品的光催化性能较好；当增加铜源的含量时,特别当铜源含量增加到0.05mol/L时,样品的光催化性能下降。当铜源含量为0.02mol/L时,样品的光催化性能随着PVP含量的增加而增加,并且当PVP的含量增加到0.5g时,负载在MWCNTs管壁上的Cu2S纳米颗粒大小均匀、分散效果最好,因此样品的性能达到最佳；然而,当继续增加PVP的含量时,特别当PVP的含量增加到0.9g时,由于部分的Cu2S纳米颗粒未成功负载在MWCNTs的管壁上,因此导致样品的光催化性能明显下降。此外,在本部分内容中,我们也分析了Cu2S/MWCNTs复合材料的光催化机理。3.同样地,在表面活性剂PVP的辅助下,以醋酸铜为铜源,DEG为溶剂和还原剂,通过高温多元醇法制备Cu2S/T-ZnOw纳米复合光催化剂,并研究不同的Cu/Zn摩尔比以及不同的PVP含量对样品的结构、形貌以及光催化性能的影响。当PVP的含量为0.5g时,Cu2S纳米颗粒的负载量随着Cu/Zn摩尔比的增加而增加；特别当Cu/Zn摩尔比增加到10%时,Cu2S纳米颗粒出现比较大的团聚。当Cu/Zn≤4%时,样品的光催化活性随着Cu/Zn摩尔比的增加而增加；然而,当继续增加Cu/Zn摩尔比时,样品的光催化活性反而下降。在Cu/Zn摩尔比为2%的条件下,当PVP的含量≤0.1g时,PVP含量越高,样品的光催化活性也越高,并且当PVP的含量为0.3g时,Cu2S纳米颗粒的大小均匀、分散效果最佳,因此样品的光催化活性最好；然而,当PVP的含量>0.1g时,样品的光催化性能下降。特别当PVP的含量增加到0.5g时,由于部分的Cu2S纳米颗粒未成功沉积在T-ZnOw表面上,导致样品的光催化活性下降很多,这说明表面活性剂PVP的含量对于样品形貌的控制以及光催化活性都有很大的影响。此外,在本部分内容中,我们也对Cu2S/T-ZnOw复合光催化剂的光催化机理进行了分析。综上所述,本论文采用高温多元醇法成功制备纳米Cu2S以及Cu2S/MWCNTs和Cu2S/T-ZnOw纳米复合材料。实验结果表明,Cu2S/MWCNTs以及Cu2S/T-ZnOw纳米复合材料对甲基橙溶液具有优异的光催化降解性能,这在环境污染物的降解方面将有很大的应用潜能。更多还原

【Abstract】 Due to the double significance of "energy conservation" and "environmental protection", semiconductor photocatalytic technology has been widely studied and used in the fields of wastewater treatment, semiconductor sterilization and the purification of environmental pollutants. Most wide bandgap semiconductors have been studied among these semiconductor photocatalysts, such as ZnO, TiO2, and SnO2. However, due to their large band gap energies, the utilization rate of the sunlight is very low for them. In addition, the recombination property of photogenerated electrons and holes, hindering the pratical applicatons of the single semiconductor. So, in order to enhance the photoactivity of the single semiconductor photocatalyst, we need to take some efficient measures to modify the single photocatalyst. As a new p-type semiconductor material with a bulk band gap in range of1.22-1.24eV, Cu2S has excellent thermal and chemical stability and is a good photoelectric material. So it has great potential applications for the solar photovoltaic and environmental purification.In this thesis, Cu2S nanomaterial and its nanocomposites have been considered as the objects and synthesized by polyol process. The samples are characterized by XRD, FESEM, EDS, XPS, FTIR and UV-Vis DRS. Besides, we studied the effect of various factors on the structure, morphology and the photoactivity of the samples and the detailed contents are as the following three aspects:1. Cu2S nanomaterials with different structure and morphology have been successfully prepared by polyol process under the different reaction conditions. Copper acetate as a precursor and diethylene glycol as both solvent and reducing agent in the polyol process. Besides, we have studied the effect of the different structure and morphology on the photocatalytic activity of the samples. When the Cu/S MRs are1:1.5and1:1, the characteristic peaks of CuS appear in the XRD spectra of the samples. However, when increases the Cu/S MR up to2:1, the XRD spectra of the samples just exhibits the characteristic peaks of Cu2S. Besides, the samples show the ability to photodegrade the methylene orange. Under the2:1Cu/S, the mean particle size of the samples increases with the increasing of the reaction temperatures, which results in decreasing the photocatalytic property. 2. Taking MWCNTs as the carriers and copper acetate as a precursor, we have successfully synthesized the Cu2S/MWCNTs nanocomposites with the assistant of poly(vinyl pyrrolidone)(PVP) by polyol process, we study the influence of the different contents of copper salt and PVP on the structure, morphology and the photoactivity of the samples. When the content of the copper salt is relatively low, the Cu2S nanoparticles are uniformly dispersed on the surface of MWCNTs and the samples exhibit excellent photoactivity. However, the photoactivity of the sample decreases with increasing the content of copper salt. Under the0.02mol/L copper salt, the photoactivity of the sample increases with increasing the PVP contents. In particularly, when increases the PVP content up to0.5g, the Cu2S nanoparticles are uniformly diposited on the surface of MWCNTs and the sample shows the optimum photoactivity. However, further increasing the PVP content, the photoactivity decreases. Expecially, when increases the PVP content up to0.9g, the photoactivity decreases very much. Besides, the photocatalytic mechanism of photoactivity enhancement for the Cu2S/MWCNTs nanocomposites is also discussed.3. Similarly, taking copper acetate as the precursor and DEG as both solvent and reducing agent, we have successfully synthesized the coupled Cu2S/T-ZnOw photocatalysts with the assistant of PVP by polyol process. The effect of Cu/Zn MR and PVP content on the structure, morphology and the photoactivity of the samples are discussed. The results show that the amounts of the Cu2S nanoparticles deposited on the surface of T-ZnOw are gradually increased with increasing the Cu/Zn under the0.5g PVP. Expecially, when increases the Cu/Zn up to10%, some nanoparticles aggregated into large clusters. When the Cu/Zn≤4%, the photoactivity increases with increasing the Cu/Zn. However, further increasing the Cu/Zn, the photoactivity decreases. Under the2%Cu/Zn, when the PVP contents≤0.1g, the photoactivity increases with increasing the PVP contents. When increases the PVP content up to0.3g, the nanoparticles are uniformly loaded on the surface of T-ZnOw and the sample exhibits more excellent photoactivity. However, when the PVP contents＞0.1g, the photoactivity decreases. In particularly, when increases the PVP content up to0.5g, some nanoparticles failed to deposite onto the surface of T-ZnOw and result in decreasing the photoactivity very much. Besides, we also discuss the photocatalytic mechanism of the coupled photocatalysts in this thesis.In this thesis, we have successfully synthesized the nano-Cu2S, Cu2S/MWCNTS and Cu2S/T-ZnOw nanocomposites. The results show that the nanocomposites exhibit excellent photoactivity for the photocatalytic degradation of methyl orange, which demonstrates the samples have good potential applicatons for the purification of environmental pollutants.更多还原