【作者】 王宇飞；

【导师】 张荻； 熊定邦；

【作者基本信息】 上海交通大学 ， 材料科学与工程， 2016， 硕士

【摘要】 作为一种常见的半导体光催化材料,二氧化钛（TiO₂）因为具有成本低、无污染、来源广泛等优越性能而备受关注,成为解决生态环境与能源匮乏的有效手段之一。然而,随着社会各行各业的迅猛发展以及科学技术的不断变革,人们对TiO₂的光催化效率和能源利用率提出了更高的要求。与此同时,由于TiO₂自身存在的一些性能缺陷,如禁带宽度较大、量子效率偏低等,成为了影响其进一步发展的桎梏。因而,如何提高TiO₂的光催化性能,拓宽TiO₂半导体在可见光范围内的光响应范围,成为了当下半导体光催化研究领域的重中之重。启迪于大自然丰富的生物结构,本文提出以具有光响应特性的蝴蝶翅膀为生物模板,借助于不同蝶翅模板,利用溶胶-凝胶法制备系列遗态TiO₂样品,并分析结构尺寸对其光响应波段的影响规律。同时,以异型紫斑蝶为生物模板制备合成遗态光子晶体结构Au/TiO₂材料,并通过一系列表征手段,分析遗态光子晶体结构慢光效应和贵金属金纳米颗粒对TiO₂光催化性能的调控作用,以及两者之间的耦合作用,为改善和提高半导体光催化功能材料的催化效率提供新的研究思路和实验依据。主要研究内容以及结果如下:1、基于改进参数后的溶胶-凝胶法,以蝴蝶翅膀为生物模板,制备合成了遗态TiO₂材料。该方法可以较好地复制蝶翅的周期性分级结构,包括脊结构、肋结构以及脊背上的薄肋结构。2、以具有类似周期性分级结构的紫斑环蝶、枯叶蝶和异型紫斑蝶为模板,制备合成系列遗态TiO₂。通过表征它们的微观形貌、结构尺寸以及光学性能,分析研究尺寸因素对遗态周期性分级结构在可见光范围内光学行为的影响。研究结果表明,只有异型紫斑蝶结构TiO₂在可见光范围内有良好的光学行为,分别在420nm与600nm处有明显的反射峰。随着“窗口”结构尺寸的增加,其可调控的波段发生红移。同时,脊背上多层薄肋,也可以对光起调控作用。3、在异型紫斑蝶形貌TiO₂基础上,制备合成遗态光子晶体结构Au/TiO₂材料（Biomorphic Au/TiO₂ photonic crystal,缩写为Au/TiO₂-BMPC）。Au/TiO₂-BMPC较好地复制了蝶翅的周期性分级结构。Au纳米颗粒尺寸约为9nm,在TiO₂基体上均匀分布。研究表明,Au/TiO₂-BMPC材料在550nm处具有较强的光吸收性能,主要归功于遗态光子晶体的慢光效应对入射光的调控作用。慢光效应使特定波段的入射光在晶体内部的传播速度减缓,且波段范围恰好覆盖了样品中Au纳米颗粒的SPR吸收峰位,使两者产生共振,从而增强了Au纳米颗粒的SPR吸收强度。4、通过光催化降解甲基橙（Methyl orange）实验,测试Au/TiO₂-BMPC样品的光催化活性。研究表明,Au/TiO₂-BMPC在240min内完全降解甲基橙,其催化速率是不具备光子晶体结构样品crushed Au/TiO₂-BMPC的5倍,是商用催化剂Au/TiO₂-P25的7倍。Au/TiO₂-BMPC样品的高光催化性能主要来源于光子晶体结构对Au纳米颗粒的SPR吸收强度的增加。除此之外,蝶翅生物模板的分级多孔结构也为光催化反应提供更为丰富的反应活性中心,提高了Au/TiO₂-BMPC样品的光催化活性。更多还原

【Abstract】 As a common photocatalyst,titanium dioxide（TiO₂）is one of the most promising material because of its outstanding properties,such as low cost,nontoxicity and chemical stability.TiO₂ could help to solve the problems of energy shortage and enviornment pollution,which are becoming more and more severe all around the world.However,with the rapid pace of industry development and technology revolution,the requirements and demands of photocatalysts are increasingly higher.Moreover,some of the drawbacks of typical photocatalysts,such as large band gap and low energy transfer efficiency,are imposing restrictions on the development of TiO₂ in the photocatalysis field.Consequently,how to enhance TiO₂’s photaocatalysis efficiency and broaden its light response range under visible-light become a focus of current research.Inspired by the abundant biomorphic structures in nature,this study raises a concept concerning biomorphic template.Based on different butterfly wings,a series biomorphic TiO₂ are fabricated by sol-gel method.The obtained samples are also detected to find out how the dimensions of periodic structure affect the photonic performance of these samples respectively.Meanwhile,gold nanoparticles are dispersed into the biomorphic TiO₂ photonic crystal（TiO₂-BMPC）to fabricate Au/TiO₂-BMPC on the basis of Euploea mulciber butterfly as template.According to the results of charaterizations,the properties and photonic performance and photocatalytic efficiency are detected,which could be used to analyze how the slow photon effect of photonic structure helps to enhance the SPR intensity of gold nanoparticles.All the work we done could offer us new sights and models for the studies of photocatalytic materials.The main contents and results are as follows:1.Based on a modified sol-gel method,biomorphic TiO₂ material is fabricated using butterfly wings as templates.The obtained samples own a well-replicated structure of butterfly wing scales,including ridges,struts and ribs.2.On the basis of Thaumantis diores,Kallima inachus and Euploea mulciber butterfly wings who have similar periodic hierachical structures,a series of biomorphic TiO₂ are synthesized.Some detections and analysis have been done to find out the connection between the dimensions and photonic performance of periodic hierachical structures under visible-light.The results show that only the sample templated from Euploea mulciber butterfly wings gives a good photonic performance,with the existance of reflection spectra at 420nm and 600nm respectively.With the increasement of the size“window”structure,the wavelength of the reflection spectrum will have a red shift.Meanwhile,the more ribs it have,the more possiblely the structure will give a good photonic performance under visible-light.3.Using Euploea mulciber butterfly wings as biomorphic template,biomorphic Au/TiO₂ photonic crystal sample（Au/TiO₂-BMPC）is obtained.The results show that the original structures of butterfly wing scales are well-replicated in the Au/TiO₂-BMPC samples.Gold nanoparticles are well-dispersed on the TiO₂ matrix,with an average size of 9 nm.It is convinced that there is an enhenced light harvesting under visible-light,due to the slow photon effect of photonic structure,which happens when the wavelength of slow photon effect matches the SPR wavelength of gold nanoparticles.As a result,the SPR intensity of gold nanoparticles could be enhanced under visible-light irradiation.4.The degradation of methyl orange test is used to detect the photocatalytic efficiency of Au/TiO₂-BMPC samples.The results show that Au/TiO₂-BMPC is able to degrade MO completely within 240 min.Compared to the contrast samples,the photocatalytic rate of Au/TiO₂-BMPC is 5 times than that of crused Au/TiO₂-BMPC,and 7times than that of Au/TiO₂-P25.The enhanced photocatalytic property could mainly ascribed to the co-work of photonic structures and gold nanoparticles.Furthermore,the hierarchical porous structures of butterfly wings offer more active sites for the photocatalysis process,which could also help increase the photocatalytic efficiency of Au/TiO₂-BMPC samples.更多还原