Electrochromic photonic crystals (PCs) have been intensively studied in the field of display, sensors, and intelligent materials due to their tunable brilliant structural colors. The mostly studied electrochromic PCs are based on the tunable lattice parameter after electrifying; namely, the electrochromic process is caused by the structural change of PCs. Besides the lattice parameter, the refractive index is another key factor to determine the structural color of PCs. Here, a kind of hollow-SiO2-supported WO3 (H-SiO2/WO3) PCs is designed, where the refractive index of the WO3 portion is changeable under charging. Benefiting from the support effect and tunable thickness of H-SiO2, large-area PC samples with good surface morphology and bright multicolor output are prepared. The reflection peaks of these composite PCs can shift by 30–90 nm, and their corresponding colors changed obviously after the voltage was applied. After being pixelated by laser-marking, the H-SiO2/WO3 PCs can dynamically display different numeric and alphabetic patterns in an electric-driven writing and erasing process. Not only does this composite PC structure broaden the color change range of WO3-based materials but also avoids the structural change in the electrochromic process. This work provides more possibilities for electrochromic PCs in the field of color-changing pattern displays.
Hydrogen peroxide (H 2 O 2 ) is an important oxidant that exists widely in biological systems and the environment, and has been extensively used in medical, environmental, food, and industrial fields. Accurate, rapid, and sensitive detection of H 2 O 2 content is of great significance in the fields of biomedicine, environmental monitoring, food safety, and public safety. In this study, a probe was developed by utilizing Rhodamine 6G (Rh6G), a readily available commercial fluorescent dye, within hollow SiO 2 photonic crystals (HSPCs) to produce an amplified fluorescent signal. Furthermore, I - were incorporated into the system, which can be oxidized to I 2 in the presence of H 2 O 2 . The I 3 - produced can react with Rh6G to form a complex that quenches the fluorescence signal, enabling highly efficient detection of H 2 O 2 . The method does not require complex organic synthesis or modification of fluorescent groups. Additionally, the sensors exhibit good performance in terms of repeated use and can also potentially detect different concentrations of ethanol solutions.
In this paper, using hollow silica microspheres as carriers, we developed a facile one-pot method for the preparation of hollow SiO2@MnO2 composite microparticles. Under a certain proportion of hollow silica microspheres and manganese salt, a novel kind of hollow urchin-like SiO2@γ-MnO2 microparticles was obtained. The structure and morphology of the composite microparticles were characterized by XRD, SEM and TEM. On this basis, using rhodamine B and methyl orange as model molecules, the oxidative degradation ability of the hollow SiO2@γ-MnO2 microparticles for organic dyes in water was investigated through UV-vis analysis technology. The urchin-like SiO2@γ-MnO2 microparticles showed excellent performance for the rapid oxidative degradation of organic dyes under acidic conditions. This study indicated that γ-MnO2 loaded on hollow materials can be used as an efficient tool for treating organic dye wastewater, and shows broad application prospects for solving environmental problems in the related industry.
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