Multiple Structural Coloring of Silk‐Fibroin Photonic Crystals and Humidity‐Responsive Color Sensing

In the biological world, numerous creatures such as butterflies, insects, and birds have exploited photonic structures to produce bicolor reflections with important biofunctions in addition to unique brilliant structural coloration. Although the mimicking of bistructural color reflection is possible, the fabrication involves a process of combined layer deposition techniques, which is complicated and less flexible. Here, a bistructural color mimicking, based on silk fibroin, is reported using a simple and inexpensive self‐assembly method. Silk‐fibroin inverse opals with different spectral positions of bistructural color reflection (i.e., ultraviolet and visible peaks, ultraviolet and near infrared peaks, and visible and near infrared peaks) are obtained by simply controlling their lattice constants. Furthermore, the inline and continuous tuning of the peak positions of bistructural color reflection can be achieved by the humidity‐induced cyclic contraction of silk fibroin. The potential applications of silk‐fibroin photonic structures in eco‐dying and multifunctional silk fabrics are also demonstrated.     

Dimer‐Based Three‐Dimensional Photonic Crystals

The self‐assembly of polystyrene dimer‐ and spherocylinder‐shaped colloids is achieved via controlled drying on glass and silicon substrates. 3D monoclinic colloidal crystal structures are determined from scanning electron microscopy images of sections prepared using focused ion‐beam (FIB) milling. Full photonic bandgaps between the eighth and ninth bands are found for a systematic range of colloidal dimer shapes explored with respect to the degree of constituent lobe fusion and radius ratio. The pseudogap between bands 2 and 3 for spherocylinder‐based monoclinic crystals is also probed using normal incidence reflection spectroscopy.     

Color tunability of upconversion emission in YBO3: Yb, Er inverse opal

Upconversion (C) light-emitting photonic band gap materials (YBO₃: Yb, Er) with inverse opal structure were prepared by a self-assembly technique in combination with a sol-gel method. The effect of the photonic stop-band on the upconversion luminescence of Er³⁺ ions has been investigated in the YBO₃: Yb, Er inverse opals. Significant suppression of the green or red UC emission was detected if the photonic band-gap overlaps with the Er³⁺ ions emission band. We successfully achieved the color tuning of the UC optical properties of the inverse opal by controlling the structure of the photonic crystal.     

2D and 3D photonic crystal materials for photocatalysis and electrochemical energy storage and conversion

This perspective reviews recent advances in inverse opal structures, how they have been developed, studied and applied as catalysts, catalyst support materials, as electrode materials for batteries, water splitting applications, solar-to-fuel conversion and electrochromics, and finally as photonic photocatalysts and photoelectrocatalysts. Throughout, we detail some of the salient optical characteristics that underpin recent results and form the basis for light-matter interactions that span electrochemical energy conversion systems as well as photocatalytic systems. Strategies for using 2D as well as 3D structures, ordered macroporous materials such as inverse opals are summarized and recent work on plasmonic–photonic coupling in metal nanoparticle-infiltrated wide band gap inverse opals for enhanced photoelectrochemistry are provided.     

Rapid Fabrication of an Inverse Opal TiO2 Photoelectrode for DSSC Using a Binary Mixture of TiO2 Nanoparticles and Polymer Microspheres

A rapid fabrication method of highly reflective TiO₂ inverse opal (IO) film exhibiting controllable thickness, high TiO₂ content, and excellent interfacial contact with glass substrate is presented. By inducing accelerated solvent evaporation during the colloidal self‐assembly process, a composite film of polystyrene (PS)/TiO₂ has been directly fabricated on a fluorine doped tin oxide (FTO) glass substrate, which exhibits the highly ordered opaline structure of PS embedded into the TiO₂ matrix. This hybrid fabrication path leads to the formation of layers with the preferred {111} face‐centered cubic (FCC) orientation parallel to the substrate and to produce a 1 cm²‐wide well‐ordered composite colloidal crystal film in less than 30 min. The film showed highly ordered FCC structure, particularly at the upper region, due to the induced solvent evaporation and exhibited a reliable light modulation at a reflectance mode. Regardless of the size of sacrificial PS microspheres, TiO₂ IO films of controllable thickness were successfully formed by varying the moving speed of the fabrication cell. The binary aqueous dispersion of tailor‐made anatase TiO₂ nanoparticles and monodisperse PS microspheres showed a high degree of dispersion stability under basic conditions. Hydrothermal treatment of the TiO₂ dispersion favored the crystallinity of the coated film and provided small volume contraction after thermal calcinations. The high degree of dispersion stability enabled to increase TiO₂ content in a binary mixture, which is more favorable toward the robust and large‐area IO film. The calcined films exhibited excellent mechanical robustness and intimate interfacial contact with the glass substrate. which in turn resulted in higher TiO₂ content near the glass substrate. The TiO₂ IO film was tested as a dye‐sensitized solar cell (DSSC) photoelectrode, and a single cell showed a relatively high photon‐to‐current conversion efficiency of 4.2%. The high TiO₂ content of IO film and its good adhesion to the FTO subratrate remarkably improved in the performance of the solar cell compared to the previous investigations where post‐infiltration of TiO₂ had been employed.     

The Preparation of Carbon Inverse Opal from Heavy Oil

In this study, a porous carbon with three-dimensionally ordered structures, namely, carbon inverse opals, was synthesized by using silica colloidal crystals as templates and three kinds of heavy oils as precursors, which may provide a route toward valuable products from heavy oil. The study shows that the drying process is of importance to the integrity of the framework that resulted in carbon inverse opals.     

垂直沉积法在GaAs衬底上制备有序SiO2胶体晶体

报道了一种利用直径为286nm的单分散SiO2胶体颗粒制备胶体晶体的方法。乙醇悬浮中的SiO2颗粒通过毛细作用力在垂直插入其中的GaAs衬底表面自组装成胶体晶体。扫描电子显微镜（SEM）和紫外-可见分光光度计对胶体晶体的形貌和光学特性进行了表征。结果显示,所得到的胶体晶体膜具有较好的三维有序结构。分析了退火对样品光子带隙的影响。     

中红外完全光子带隙Ge反蛋白石三维光子晶体的制备

采用溶剂蒸发对流自组装法将单分散二氧化硅（SiO2）微球组装形成三维有序胶体晶体模板。以锗烷（GeH4）为先驱体气,用等离子增强化学气相沉积法向胶体晶体的空隙中填充高折射率材料Ge。酸洗去除二氧化硅微球,得到Ge反蛋白石三维光子晶体。通过扫描电镜、X射线衍射仪和傅立叶变换显微红外光谱仪对锗反蛋白石的形貌、成分和光学性能进行了表征。结果表明：Ge在SiO2微球空隙内填充致密均匀,得到的锗为多晶态,锗反蛋白石为三维有序多孔结构。锗反蛋白石的测试光谱图有明显的光学反射峰,表现出光子带隙效应。测试的完全光子带隙位于中红外3.4µm处,测试的光学性能与理论计算基本吻合。     

磷酸盐与氟化物混合乳浊玻璃的研究

介绍了用磷酸盐和氟化物混合乳浊的乳浊玻璃,借助扫描电子显微镜(SEM),X射线衍射(XRD),荧光X射线分析(EDX)技术观察了这些玻璃的分相形貌和显微结构,讨论了乳浊机理及乳浊剂用量与乳浊度的关系,通过熔制试验,也谈到了乳浊玻璃的熔制性能对耐火材料的侵蚀情况。