A Bioinspired Ag Nanoparticle/PPy Nanobowl/TiO2 Micropyramid SERS Substrate

In this paper, the micropyramid structure was transferred to the TiO₂ substrate by soft imprinting. Then, the PPy nanobowls were assembled onto the surface of the TiO₂ micropyramids through the induction of the PS template. Finally, a layer of Ag nanoparticles was deposited on the surface of PPy nanobowls to form a novel Ag nanoparticle/PPy nanobowl/TiO₂ micropyramid SERS substrate. Its structure is similar to the bioinspired compound eyes. This substrate exhibited excellent antireflection, ultra-sensitivity, excellent uniformity, and recyclability. The concentration of R6G molecules can be detected as low as 10^-9 mol/L, and the Raman enhancement factor can reach 3.4 × 10⁵. In addition, the excellent catalytic degradation performance of the substrate ensures recyclability. This work proves that the micropyramid structure can be applied to other SERS materials besides silicon by the above methods, which broadens the selection range of composite SERS materials.

A novel photothermal, self-healing and anti-reflection water evaporation membrane

For the solar water evaporation system, there are no reports on the self-healing support, which is crucial for the sustainable use of solar evaporation membrane. In this work, a self-healing hydrogel is prepared via free radical copolymerization with covalent cross-linking and coordination cross-linking and is used as a photothermal water evaporation support. The photothermal material is then introduced into the hydrogel by physically doping acetylene carbon black. At the same time, inverted micro-pyramids are fabricated on the surface of the hydrogel by soft imprint to increase the utilization efficiency of incident light. The water evaporation rate of the composite membrane can reach 1.58 kg m-2 h-1, and the breaking elongation is 1580%. It can self-heal after it is completely broken, and can still be stretched 3 times its original length. The design of this self-healing photothermal membrane will provide a new idea for its application in a harsh outdoor environment.

Light-Trapping SERS Substrate with Regular Bioinspired Arrays for Detecting Trace Dyes

Recently, few studies have focused on the light-trapping surface-enhanced Raman scattering (SERS) substrate combined with Si micropyramids and Ag (or Au). However, the Si micropyramids possess no ordered period, which not only affects the repeatability of the SERS signal but also affects the theoretical exploration. Here, the ordered micropyramids with strong light-trapping capability were fabricated by utilizing unconventional nanosphere lithography and anisotropy wet etching technique. Then, the Ag nanobowls were assembled on the ordered micropyramids to form the SERS substrate with bioinspired compound-eyes structure by utilizing the liquid-solid interface self-assembly and transfer technique. Especially, the evidence for the contribution of antireflective Si micropyramids to Raman enhancement was first presented. For this bioinspired SERS substrate, the lowest concentration of R6G that can be detected is 10^-13 M with the level of a single molecule, and the relative standard deviation (RSD) is 3.68%. Meanwhile, the quantitative analysis and qualitative analysis can be realized. Especially, simultaneous trace detection of four common dyes (R6G, CV, MG, and MB) in food can be realized, suggesting that this SERS substrate will have a good application prospect in the field of optical sensors.

Bioinspired Microstructured Materials for Optical and Thermal Regulation

Precise optical and thermal regulatory systems are found in nature, specifically in the microstructures on organisms' surfaces. In fact, the interaction between light and matter through these microstructures is of great significance to the evolution and survival of organisms. Furthermore, the optical regulation by these biological microstructures is engineered owing to natural selection. Herein, the role that microstructures play in enhancing optical performance or creating new optical properties in nature is summarized, with a focus on the regulation mechanisms of the solar and infrared spectra emanating from the microstructures and their role in the field of thermal radiation. The causes of the unique optical phenomena are discussed, focusing on prevailing characteristics such as high absorption, high transmission, adjustable reflection, adjustable absorption, and dynamic infrared radiative design. On this basis, the comprehensive control performance of light and heat integrated by this bioinspired microstructure is introduced in detail and a solution strategy for the development of low-energy, environmentally friendly, intelligent thermal control instruments is discussed. In order to develop such an instrument, a microstructural design foundation is provided.