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Ultraviolet patterns of flowers revealed in polymer replica – caused by surface architecture
摘要： Angiosperms and their pollinators are adapted in a close co-evolution. For both the plants and pollinators, the functioning of the visual signaling system is highly relevant for survival. As the frequency range of visual perception in many insects extends into the ultraviolet (UV) region, UV-patterns of plants play an important role in the flower–pollinator interaction. It is well known that many flowers contain UV-absorbing pigments in their petal cells, which are localized in vacuoles. However, the contribution of the petal surface microarchitecture to UV-reflection remains uncertain. The correlation between the surface structure and its reflective properties is also relevant for biomimetic applications, for example, in the field of photovoltaics. Based on previous work, we selected three model species with distinct UV-patterns to explore the possible contribution of the surface architecture to the UV-signaling. Using a replication technique, we transferred the petal surface structure onto a transparent polymer. Upon illumination with UV-light, we observed structural-based patterns in the replicas that were surprisingly comparable to those of the original petals. For the first time, this experiment has shown that the parameters of the surface structure lead to an enhancement in the amount of absorbed UV-radiation. Spectrophotometric measurements revealed up to 50% less reflection in the UV-absorbing regions than in the UV-reflecting areas. A comparative characterization of the micromorphology of the UV-reflecting and UV-absorbing areas showed that, in principle, a hierarchical surface structure results in more absorption. Therefore, the results of our experiments demonstrate the structural-based amplification of UV-reflection and provide a starting point for the design of bioinspired antireflective and respectively strongly absorbing surfaces.
关键词： hierarchical structures,biomimetics,light absorption,light harvesting,light reflection
更新于2025-10-22 19:40:53
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Ultrafast methanol sensing properties of nano-spindle like In2O3 hierarchical structures with oxygen vacancies
摘要： Unique nano-spindle like In2O3 hierarchical structures have been successfully prepared using a simplified solvothermal method. The micromorphology and crystalline structure of the as-obtained are characterized by SEM, TEM, and XRD. Morphology analysis reveals that the nano-spindle like In2O3 hierarchical structures are composed of numerous ordered nanorods. The optical properties of the samples are also studied, and it is confirmed that the presence of a large amount of oxygen vacancies in the as-synthesized samples. The as-synthesized nano-spindle like In2O3 hierarchical structures are used for the detection of the methanol gas. The sensing properties of the as-manufactured sensor are carefully discussed and the sensor shows outstanding methanol sensing performance, especially ultrafast response time (<1 s). The sensing mechanism is also discussed. This work offers the possibility to manufacture low-cost, high-performance methanol sensor based on the as-synthesized nano-spindle like In2O3 hierarchical structures.
关键词： Oxygen vacancies,Methanol sensing performance,Hierarchical structures,Nano-spindle like In2O3
更新于2025-09-23 15:22:29
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Synthesis and photocatalytic activity of BiOBr hierarchical structures constructed by porous nanosheets with exposed (110) facets
摘要： BiOBr hierarchical structures were successfully synthesized through a solvothermal process assisted with citric acid using methanol as a solvent. The as-synthesized BiOBr hierarchical structures have diameters of ca. 1 μm, and assembled by numerous porous nanosheets with exposed (110) facets. Results indicated that the crystal growth and morphology structures of BiOBr were significantly influenced by the amount of citric acid, the solvothermal time and the solvent used in reaction. In addition, the as-synthesized BiOBr hierarchical structures exhibited high photocatalytic activity on the degradation of methyl orange under either UV light or simulated sunlight illumination, due to the larger specific surface area and unique hierarchical structures assembled by numerous BiOBr porous nanosheets.
关键词： photocatalytic,citric acid,hierarchical structures,solvothermal,BiOBr
更新于2025-09-23 15:22:29
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Oriented ZnmIn2Sm+3@In2S3 heterojunction with hierarchical structure for efficient photocatalytic hydrogen evolution
摘要： It remains a great challenge to design and prepare highly efficient semiconductor-based photocatalysts for water splitting. To achieve this goal, the design of oriented heterojunctions for efficient carrier transport and separation is a new strategy based on their conductive anisotropy. Herein, a novel oriented J-J type ZnmIn2Sm+3@In2S3 heterojunction photocatalyst with hierarchical structures is fabricated with the assistance of oxalic acid. The hierarchical structures consist of ‘flower-like’ hollow ZnmIn2Sm+3 microspheres with epitaxially grown quantum confined In2S3 along the petal rims (J-J type heterojunction). This heterojunction improves the transport and separation of the photoexcited carriers, and extends the visible-light response range. Thus, the heterojunction photocatalyst exhibits significantly enhanced photocatalytic activity with a hydrogen evolution rate of 330 μmol h-1, which is about 4 times higher than that of single ZnIn2S4. The findings provide new insights to construct efficient oriented heterojunctions for anisotropic semiconductors.
关键词： ZnmIn2Sm+3,hierarchical structures,oxalic acid,oriented heterjunctions,In2S3
更新于2025-09-23 15:21:21
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Directed Emission from Self‐Assembled Microhelices
摘要： Bottom-up assembly can organize simple building blocks into complex architectures for light manipulation. The optical properties of self-assembled polycrystalline barium carbonate/silica double helices are studied using fluorescent Fourier and Mueller matrix microscopy. Helices doped with fluorescein direct light emission along the long axis of the structure. Furthermore, light transmission measured normal and parallel to the long axis exhibits twist sense-specific circular retardance and waveguiding, respectively, although the measurements suffer from depolarization. The helices thus integrate highly directional emission with enantiomorph-specific polarization. This optical response emerges from the arrangement of nanoscopic mineral crystallites in the microscopic helix, and demonstrates how bottom-up assembly can achieve ordering across multiple length scales to form complex functional materials.
关键词： bioinspired materials,optical microscopy,hierarchical structures,polarimetry,self-assembly
更新于2025-09-12 10:27:22
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Enhanced CH4 sensitivity of porous nanosheets-assembled ZnO microflower by decoration with Zn2SnO4
摘要： In recent years, design and synthesis of heterostructured nanomaterials with high gas-sensing performance for detection of flammable and toxic gases has attracted much research interest. In this paper, pristine and Zn2SnO4-decorated ZnO microflowers with the size about 2?5 μm and assembled by porous nanosheets of about 15 nm in thickness were successfully synthesized via a simple solvothermal method and subsequent calcination process. The methane (CH4) sensing properties of the prepared Zn2SnO4/ZnO were investigated and compared with that of the pure ZnO counterpart. It was found that after decorating with a small amount of Zn2SnO4, the ZnO sensor showed an improved gas sensing properties to CH4. At optimum operating temperature of 250 oC, the sensor based on SZ2 (Zn2SnO4/ZnO composite with the optimal Zn2SnO4 contend) shows a response as high as 27.2 to 1000 ppm CH4, which is about 3.2 times higher than that of SZ0 (pristine ZnO) sensor. Meanwhile, the SZ2 sensor also shows a fast response and recover characteristic, low detection limit (1.48 ppm), good repeatability and long-term stability. The Zn2SnO4/ZnO heterostructures related CH4 sensing mechanism was discussed.
关键词： CH4,Zn2SnO4,Hierarchical structures,Gas sensor,Heterostructures
更新于2025-09-12 10:27:22
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Gas Sensing Performances of ZnO Hierarchical Structures for Detecting Dissolved Gases in Transformer Oil: A Mini Review
摘要： Power transformer is one of the critical and expensive apparatus in high voltage power system. Hence, using highly efficient gas sensors to real-time monitor the fault characteristic gases dissolved in transformer oil is in pressing need to ensure the smooth functionalization of the power system. Till date, as a semiconductor metal oxide, zinc oxide (ZnO) is considered as the promising resistive-type gas sensing material. However, the elevated operating temperature, slow response, poor selectivity and stability limit its extensive applications in the field of dissolved gases monitoring. In this respect, rigorous efforts have been made to offset the above-mentioned shortcomings by multiple strategies. In this review, we first introduce the various ZnO hierarchical structures which possess high surface areas and less aggregation, as well as their corresponding gas sensing performances. Then, the primary parameters (sensitivity, selectivity and stability) which affect the performances of ZnO hierarchical structures based gas sensors are discussed in detail. Much more attention is particularly paid to the improvement strategies of enhancing these parameters, mainly including surface modification, additive doping and ultraviolet (UV) light activation. We finally review gas sensing mechanism of ZnO hierarchical structure based gas sensor. Such a detailed study may open up an avenue to fabricate sensor which achieve high sensitivity, good selectivity and long-term stability, making it a promising candidate for transformer oil monitor.
关键词： ZnO,sensitivity,gas sensors,hierarchical structures,stability,gas sensing mechanism,selectivity
更新于2025-09-10 09:29:36