基于氧化钛纳米片的复合材料及其光催化、储能性能研究

发布时间：2018-04-14 08:09

  本文选题：二维纳米材料 + 二氧化钛　； 参考：《南京大学》2017年博士论文

【摘要】：自2004年石墨烯的发现以来,具有原子级厚度和高度各向异性的超薄二维纳米材料引起了人们广泛关注。这类独特维度尺寸受限结构具有的量子限域效应和表面效应使其表现出与普通体相材料不同的物理化学性质,在催化、电化学、吸附、分离、电学、光学、磁学等诸多领域具有巨大的应用潜力,引发了全球范围内的研究热潮。氧化钛纳米片在环境、储能、催化等诸多方面具有重要的的应用前景,对其结构调控、组装及性能研究尚少见报道,大量制备厚度1nm左右的高质量、结构明确的氧化钛超薄纳米片仍是一个挑战。本文主要以超薄TiO2纳米片材料为研究对象,通过液相剥离的方法制备了单层钛酸盐纳米片(TiONS),并进一步研究其转晶、组装、复合结构调控以及其光催化、电化学储能等性能,取得了如下研究成果:1.发展了超薄纳米片负载纳米颗粒避免其堆叠复合的方法。通过液相剥离的方法成功制备了钛酸盐纳米片、α-ZrP纳米片、氧化石墨烯、镁铝水滑石纳米片等溶胶。(1)以单层钛酸盐纳米片(TiONS)为载体,于液相中负载Pd,得到湿状Pd/TiONS,将其直接用于液相苯酚选择性加氢制备环已酮反应。载体TiONS不发生过度堆叠复合,纳米片厚约0.9nm,Pd颗粒约1.9nm,具有高比表面积,该催化剂表现出较干燥Pd/TiONS更高的活性;(2)将液相剥离的超薄纳米片与14nm大小的SiO2纳米颗粒复合,通过SiO2纳米颗粒的支撑保护,有效地避免纳米片在进一步的干燥及热处理中发生堆叠烧结,得到了 SiO2纳米颗粒支撑超薄纳米片的复合材料。2.超薄二氧化钛纳米片的制备及结构与性能研究。在前一工作的基础上,通过精细的调变,优化了有效保持钛酸盐纳米片超薄结构的最低SiO2用量。进一步将钛酸盐纳米片500℃热处理使其由纤铁矿型结构钛酸盐转变为锐钛矿结构二氧化钛,氧化钛纳米片厚约0.6nm,主要暴露高能(116)晶面,且带隙值较块体锐钛矿增大了约0.4 eV,在催化紫外光降解罗丹明B反应中表现出优异的性能。在获得的锐钛矿纳米片-Si02纳米颗粒复合材料的基础上,通过NaOH溶液除去SiO2,进一步的酸化脱Na+再煅烧,获得比表面积达200 m2 g~(-1)自支撑的锐钛矿二氧化钛纳米片。3.TiO2@carbon复合材料的控制合成与锂离子电池储能应用。我们将液相剥离的TiONS与有机碳源作用并原位碳化控制合成了炭层紧密包覆的TiO2@carbon核壳型纳米片,TiO2纳米片的厚度约1.1nm,炭层的厚度约为2.2 nm,超薄的氧化钛纳米片缩短了锂离子的运动路程,有利于锂离子的快速嵌入/脱出,包覆的炭层有效地提高了材料整体的导电性,同时炭的引入使其本身的容量贡献极大地提高了材料整体的容量,并进一步提高了二维结构的稳定性。将该材料用作锂离子电池负极材料,在0.23 Ag~(-1)的电流密度下循环300次后,可逆容量高达549 mAh g~(-1),在4.6 A g~(-1)的高倍率下循环2000次后,可逆容量仍高达385 mAh g~(-1)。
[Abstract]:Since the discovery of graphene in 2004, ultrathin two-dimensional nanomaterials with atomic thickness and high anisotropy have attracted much attention.The quantum confinement and surface effects of this unique dimensional size limited structure exhibit physical and chemical properties different from those of ordinary bulk materials in catalysis, electrochemistry, adsorption, separation, electricity, optics,Many fields, such as magnetism, have great application potential, which has triggered a worldwide research boom.Titanium oxide nanocrystals have important applications in environment, energy storage, catalysis and so on. There are few reports on the structure control, assembly and performance of titanium oxide nanocrystals, and a large amount of high quality 1nm with thickness is prepared.Clearly structured titanium oxide nanocrystals remain a challenge.In this paper, ultrathin TiO2 nanocrystals were prepared by liquid phase stripping method, and their properties of transprystallization, assembly, composite structure control, photocatalytic and electrochemical energy storage were studied.The following research results have been achieved: 1.The method of loading nanocrystalline particles to avoid stacking and recombination was developed.TIO _ 3 nanocrystals, 伪 -ZrP, graphene oxide and magnesia-aluminum hydrotalcite nanoparticles were successfully prepared by liquid-phase stripping method. The monolayer titanate nanoparticles (TiONSs) were used as the support.The wet PD / TiONSs were obtained by loading PD in liquid phase, which was directly used for selective hydrogenation of phenol to cyclohexanone in liquid phase.There was no excessive stacking of the supported TiONS, and the thickness of the nanoparticles was about 0.9 nm, with a high specific surface area. The catalyst showed a higher activity than dry Pd/TiONS.Through the support and protection of SiO2 nanoparticles, the stacking sintering of nanocrystalline particles in further drying and heat treatment was avoided, and the composite material. 2. 2 of SiO2 nanoparticles supported ultrathin nanocrystals was obtained.Preparation, structure and Properties of ultrathin Titanium dioxide nanoparticles.On the basis of the previous work, the minimum amount of SiO2 was optimized to keep the ultrathin structure of titanate nanocrystals by fine-tuning.The titanate nanocrystalline was further heat treated at 500 鈩，

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