生长助剂对微纳米级二氧化钛颗粒形貌和光吸收性能的影响

以钛酸丁酯为钛源,氟化氢(HF)为形貌控制剂,溶剂(乙酸乙酯、乙酸和异丙醇)为生长助剂,通过溶剂热法合成了不同形貌的二氧化钛(TiO2).利用X射线衍射谱(XRD)分析样品的物相,扫描电子显微镜(SEM)表征TiO2颗粒的形貌,氮气吸附-脱附实验测量样品的比表面积,紫外可见吸收光谱测试样品的光吸收能力.结果表明:乙酸乙酯、乙酸和异丙醇作为生长助剂时,相应地得到球形、片状和比表面积高达155.58m2 ·g-1的花状结构.乙酸乙酯对样品形貌的影响大于HF.乙酸和异丙醇对HF具有协同作用,不同形貌的TiO2颗粒的紫外光吸收的强弱顺序为醇-TiO2,酸-TiO2,酯-TiO2.     

纳米TiO_2半导体催化活性的研究进展

纳米TiO2半导体催化技术具有广阔的应用前景,近年来半导体光催化已成为功能陶瓷材料、光化学、环境保护、生物技术等领域的研究热点之一。本文简要介绍了近年来国内外纳米TiO2半导体光催化剂的研究进展,主要包括纳米TiO2光催化剂的作用机理及结构的影响;提高催化活性的方法,指出了表面贵金属沉积、复合半导体、金属离子掺杂和表面光敏化是提高催化活性和催化效率的有效途径。     

Conductive Transparent TiNx/TiO2 Hybrid Films Deposited on Plastics in Air Using Atmospheric Plasma Processing

The successful deposition of conductive transparent TiN_x/TiO₂ hybrid films on both polycarbonate and silicon substrates from a titanium ethoxide precursor is demonstrated in air using atmospheric plasma processing equipped with a high‐temperature precursor delivery system. The hybrid film chemical composition, deposition rates, optical and electrical properties along with the adhesion energy to the polycarbonate substrate are investigated as a function of plasma power and plasma gas composition. The film is a hybrid of amorphous and crystalline rutile titanium oxide phases and amorphous titanium nitride that depend on the processing conditions. The visible transmittance increases from 71% to 83% with decreasing plasma power and increasing nitrogen content of the plasma gas. The film resistivity is in the range of ～8.5 × 10¹ to 2.4 × 10⁵ ohm cm. The adhesion energy to the polycarbonate substrate varies from ～1.2 to 8.5 J/m² with increasing plasma power and decreasing plasma gas nitrogen content. Finally, annealing the film or introducing hydrogen to the primary plasma gas significantly affects the composition and decreases thin‐film resistivity.     

Fe/TiO_2纳米复合物的制备、表征及其性能

采用溶胶-凝胶结合氢气还原方法,制备了Fe与TiO2两相共存的纳米复合物。透射电子显微镜(TEM)图片显示,纳米复合物的颗粒大小为100~300nm,且具有明显的核/壳结构。X射线衍射结果表明,纳米复合物中存在a-Fe与金红石型TiO2结构,未发现其他杂相。振动样品磁强计(VSM)的测量结果表明,样品具有较高的比饱和磁化强度。研究表明,通过控制前驱物的用量,能有效改变样品的磁性。热重分析(TGA)结果表明,样品具备很好的抗氧化性。复合介电谱和磁谱表明,在测量的微波频率范围内,样品的介电损耗大于磁损耗。     

TiO_2可见光光催化的研究进展

扩展TiO2催化的响应光谱范围,已成为目前TiO2光催化最具挑战性的课题之一。从TiO2体相掺杂、表面敏化等方面对近年来实现TiO2可见光光催化的途径和方法进行了简要总结。要进一步提高光催化效率还需:深入理解现有TiO2可见光体系的光催化机理;发现更高效的体相掺杂剂和表面敏化剂;设计和控制掺杂剂和表面敏化剂存在形态。     

Enhanced Ionic/Electronic Transport in Nano‐TiO2/Sheared CNT Composite Electrode for Na+ Insertion‐based Hybrid Ion‐Capacitors

Ion‐insertion capacitors show promise to bridge the gap between supercapacitors of high power densities and batteries of high energy densities. While research efforts have primarily focused on Li⁺‐based capacitors (LICs), Na⁺‐based capacitors (SICs) are theoretically cheaper and more sustainable. Owing to the larger size of Na⁺ compared to Li⁺, finding high‐rate anode materials for SICs has been challenging. Herein, an SIC anode architecture is reported consisting of TiO₂ nanoparticles anchored on a sheared‐carbon nanotubes backbone (TiO₂/SCNT). The SCNT architecture provides advantages over other carbon architectures commonly used, such as reduced graphene oxide and CNT. In a half‐cell, the TiO₂/SCNT electrode shows a capacity of 267 mAh g^?1 at a 1 C charge/discharge rate and a capacity of 136 mAh g^?1 at 10 C while maintaining 87% of initial capacity over 1000 cycles. When combined with activated carbon (AC) in a full cell, an energy density and power density of 54.9 Wh kg^?1 and 1410 W kg^?1, respectively, are achieved while retaining a 90% capacity retention over 5000 cycles. The favorable rate capability, energy and power density, and durability of the electrode is attributed to the enhanced electronic and Na⁺ conductivity of the TiO₂/SCNT architecture.     

Creating an Air‐Stable Sulfur‐Doped Black Phosphorus‐TiO2 Composite as High‐Performance Anode Material for Sodium‐Ion Storage

With the increasing demand for low cost, long lifetime, high energy density storage systems, an extensive amount of effort has recently been focused on the development of sodium‐ion batteries (SIBs), and a variety of cathode materials have been discovered. However, looking for the most suitable anode material for practical application is a major challenge for SIBs. Herein, a high capacity sulfur‐doped black phosphorus‐TiO₂ (TiO₂‐BP‐S) anode material for SIBs is first synthesized by a feasible and large‐scale high‐energy ball‐milling approach, and its stability in air exposure is investigated through X‐ray photoelectron spectroscopy. The morphology of TiO₂‐BP‐S is characterized using transmission electron microscopy, indicating that the TiO₂ nanoparticles produce P? Ti bonds with BP. The TiO₂‐BP‐S composite with P? S and P? Ti bonds exhibits excellent stability in air and the superior electrochemical performance. For example, the discharge specific capacity is up to 490 mA h g^?1 after 100 cycles at 50 mA g^?1, and it remains at 290 mA h g^?1 after 600 cycles at 500 mA g^?1. Meanwhile, the scientific insight that the formation of stable P? S and P? Ti bonds can provide a guide for the practical large‐scale application of SIBs in other titanium base and black phosphorus materials is looked forward.     

Metal–Organic Framework Derived Narrow Bandgap Cobalt Carbide Sensitized Titanium Dioxide Nanocage for Superior Photo‐Electrochemical Water Oxidation Performance

Despite recent progress in photo‐electrochemical (PEC) water oxidation systems for TiO₂‐based photoanodes, PEC performance improvement is still seriously hampered due to poor carrier transport efficiency and sluggish surface water oxidation kinetics of pristine TiO₂. Herein, for the first time a brand new metal–organic framework (MOF)‐derived Co₃C nanosheet with narrow bandgap energy is demonstrated, to effectively sensitize TiO₂ hollow cages as a heterostructure photoanode for PEC water oxidation. It is found that MOF‐derived Co₃C nanosheet with narrow bandgap characteristic can simultaneously accelerate the surface water oxidation kinetics and extend the light harvesting range of pristine TiO₂. Meanwhile, a uniquely matched type‐II heterojunction constructed between MOF‐derived Co₃C and TiO₂ results in an evidently spontaneous e^?/h⁺ separation. MOF‐derived Co₃C/TiO₂ heterostructure photoanodes bring about drastically improved PEC water oxidation performance. Specifically, MOF‐derived Co₃C‐3/TiO₂ photoanode with an optimized content of Co₃C achieves the highest photocurrent density and charge separation efficiency of 2.6 mA cm^?2 and 92.6% at 1.23 V versus reversible hydrogen electrode, corresponding to 201% and 152% improvement compared with pristine TiO₂ nanocages. The ingeniously prepared MOF‐derived Co₃C carbide with narrow bandgap energy as a cocatalyst paves new way to construct potentially high performance solar‐energy conversion system.     

Photosensitization of TiO2 Nanostructures with CdS Quantum Dots: Particulate versus Tubular Support Architectures

TiO₂ nanotube arrays and particulate films are modified with CdS quantum dots with an aim to tune the response of the photoelectrochemical cell in the visible region. The method of successive ionic layer adsorption and reaction facilitates size control of CdS quantum dots. These CdS nanocrystals, upon excitation with visible light, inject electrons into the TiO₂ nanotubes and particles and thus enable their use as photosensitive electrodes. Maximum incident photon to charge carrier efficiency (IPCE) values of 55% and 26% are observed for CdS sensitized TiO₂ nanotube and nanoparticulate architectures respectively. The nearly doubling of IPCE observed with the TiO₂ nanotube architecture is attributed to the increased efficiency of charge separation and transport of electrons.