is currently based on structures floating on water. [11,13,17,[19][20][21][22] By using graphite membranes, the highest solar thermal efficiency (see Equation (4)) of 85% has been reported under an equivalent solar intensity of 10 suns. [13] One of the main drawback of this approach, besides the large light intensity requirement, lies in the fact that carbon-based systems (both graphite and graphene) are vulnerable to the contamination of pollutants or salt in the water, thus limiting the recyclability of the membrane after prolonged use.In this article, we developed a different approach, which makes use of a flat-optics metasurface [23][24][25][26][27][28] composed of suitably engineered plasmonic nanoparticles. [29,30] Plasmonics structures, thanks to the possibility of localizing light energy at the nanoscale, have demonstrated a great potential in converting light energy into heat for a variety of photothermal applications. [31][32][33][34] In plasmonic steam generation, the best results have been obtained with porous films, which reported efficiencies of ≈60% under 1 sun. [19,20] The efficiency limits of these structures originate from the resonant nature of classical plasmonic materials, which usually harvest energy only at characteristic frequencies of the solar spectrum. In our metasurface, we overcome this problem by using a completely new mechanism of heat generation supported by biomimetic nanoparticles that behave as an almost ideal blackbody. These nanoparticles mimic the shell of an Asian specie of beetle that possesses an exceptional ability in controlling light reflection. [29] Even when these nanoparticles are used in extremely small volumes, they completely absorb input photons at all frequencies and polarizations. By suitably dispersing these nanoparticles in a paper film, we created a metasurface with a remarkable ability in transforming light energy into heat, leading to a dramatic increase of solar thermal generation efficiency if compared to classical structures. Our nanoparticles are fully recyclable from the paper substrate and invulnerable to saline water corrosion, representing an ideal system for solar steam generation. [35] 2. Results Sample Design and Fabrication

Cluster-spin glass and ferroelectric relaxors have been observed in defectcontaining ferromagnetic systems and ferroelectric systems, respectively. However, it is unclear whether or not an analogous glass state exists in the physically parallel ferroelastic (or martensitic) systems. In the 1990s, theoretical studies suggested that premartensitic tweed could be viewed as a strain glass. However, there has been no experimental verification of this hypothesis. In this paper, we provide an experimental test of this hypothesis by measuring the possible glass signatures in two well-known premartensitic tweed systems prior to their martensitic transformation: one Ni 63 Al 37 and the other Ti 50 Ni 47 Fe 3 martensitic alloy. Our experiments show that no glass signatures exist for the premartensitic tweed in both systems. There is no mechanical susceptibility/modulus anomaly in the tweed temperature regime, suggesting no glass transition exists. The tweed remains ergodic, inconsistent with a frozen glass. These two critical experiments show that premartensitic tweed is not a frozen glass state. We demonstrate that strain glass exists in ferroelastic/martensitic systems but only in defect-containing ferroelastic/martensitic systems with defect concentration exceeding a critical value. This strain glass is a mechanical analogue of cluster-spin glass or ferroelectric relaxors, and possesses all the features of a glass. We further show that the tweed is equivalent to an 'unfrozen state' of a strain glass. Finally, we demonstrate that the microscopic origin of the strain glass can be easily understood in analogy with the behavior of a 'defect-containing domino array'.

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Information encryption and security is a prerequisite for information technology, which can be realized by an optical metasurface owing to its arbitrary manipulation over the wavelength, polarization, phase, and amplitude of light. So far information encoding can be implemented by the metasurface in one-dimensional (1D) mode (either wavelength or polarization) only with several combinations of independent channels. Herein, we design dielectric metasurfaces by multiplexing for information encoding in a two-dimensional (2D) mode of both wavelength and polarization. Sixty-three combinations made out of six independent channels by two circular polarization states (RCP and LCP) and three visible wavelengths (633, 532, and 473 nm) are experimentally demonstrated, in sharp contrast with seven combinations by three independent channels in 1D mode. This 2D mode encoding strategy enhances the encryption security dramatically and paves a novel pathway for escalating the security level of information in multichannel information encryption, anticounterfeiting, optical data storage, and information processing.

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Accurate design of high‐performance 3D surface‐enhanced Raman scattering (SERS) probes is the desired target, which is possibly implemented with a prerequisite of quantifying formidable multiple coupling effects involved. Herein, by combining theory and experiments on 3D periodic Au/SiO 2 nanogrid models, a generalized methodology of accurately designing high performance 3D SERS probes is developed. Structural symmetry, dimensions, Au roughness, and polarization are successfully correlated quantitatively to intrinsic localized electromagnetic field (EMF) enhancements by calculating surface plasmon polariton (SPP), localized surface plasmon resonance (LSPR), optical standing wave effects, and their couplings theoretically, which is experimentally verified. The hexagonal SERS probes optimized by this methodology realize over two orders of magnitudes (405 times) improvement of detection limit for Rhodamine 6G model molecules (2.17 × 10 −11 m ) compared to the unoptimized probes with the same number density of hot spots, an enhancement factor of 3.4 × 10 8 , a uniformity of 5.52%, and are successfully applied to the detection of 5 × 10 −11 m Hg ions in water. This unambiguously results from the Au roughness‐independent extra 144% contribution of LSPR effects excited by SPP interference waves as secondary sources, which is very unusual to be beyond the conventional recognition.

In this work, a facile strategy was proposed to prepare a series of brushlike thermoplastic polyurethane (TPU) coatings with mechanically robust, self-cleaning, and icephobic performance. Through a simple multicomponent click reaction of thiolactone with a diamine compound and mono-ethenyl-terminated polydimethylsiloxane (mono-ethenyl-PDMS), a diol with amide groups and flexible PDMS was synthesized, and a novel TPU could be obtained productively by a reaction of isocyanate and diol. The unique chain structure endowed TPU films with ascendant self-stratifying properties. During solvent vapor annealing, flexible PDMS chains migrated and enriched to the surface while urethane linkages with a strong interaction tended to locate at the substrate. Based on this, TPU-PDMS films exhibited mechanically robust property, and the tensile strength value of TPU-PDMS-3 showed a sharp increase to 48.62 MPa. The resultant TPU-PDMS-10 coatings exhibited a water repellent behavior and possessed superior movability of droplet water, and also the dirt on it could be readily removed by rinsing with water without leaving any traces. Furthermore, three different criteria were used to characterize the icephobic performance. The coatings exhibited a significantly lower freezing point (approximately −27 °C) of supercooled water, longer delay-icing time, and less ice adhesion shear strength. Therefore, these novel brushlike TPU coatings have tremendous potential applications.

The direct conversion of solar energy into fuels or feedstock is an attractive approach to address increasing demand of renewable energy sources. Photocatalytic systems relying on the direct photoexcitation of metals have been explored to this end, a strategy that exploits the decay of plasmonic resonances into hot carriers. An efficient hot carrier generation and collection requires, ideally, their generation to be enclosed within few tens of nanometers at the metal interface, but it is challenging to achieve this across the broadband solar spectrum. Here the authors demonstrate a new photocatalyst for hydrogen evolution based on metal epsilon-near-zero metamaterials. The authors have designed these to achieve broadband strong light confinement at the metal interface across the entire solar spectrum. Using electron energy loss spectroscopy, the authors prove that hot carriers are generated in a broadband fashion within 10 nm in this system. The resulting photocatalyst achieves a hydrogen production rate of 9.5 µmol h cm that exceeds, by a factor of 3.2, that of the best previously reported plasmonic-based photocatalysts for the dissociation of H with 50 h stable operation.