Flexible and water-insoluble regenerated silk materials have caught considerable interest due to their mechanical properties and numerous potential applications in medical fields. In this study, regenerated Mori (China), Thai, Eri, Muga, and Tussah silk films were prepared by a formic acid-calcium chloride (FA) method, and their structures, morphologies, and other physical properties were comparatively studied through Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray scattering (WAXS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). FTIR results demonstrated that the secondary structures of those five types of silk films are different from those of their respective natural silk fibers, whose structures are dominated by stacked rigid intermolecular β-sheet crystals. Instead, intramolecular β-sheet structures were found to dominate these silk films made by FA method, as confirmed by WAXS. We propose that silk I-like structures with intramolecular β-sheets lead to water insolubility and mechanical flexibility. This comparative study offers a new pathway to understanding the tunable properties of silk-based biomaterials.

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Abstract

Electrical switching of ferroelectric domains and subsequent domain wall motion promotes strong piezoelectric activity, however, light scatters at refractive index discontinuities such as those found at domain wall boundaries. Thus, simultaneously achieving large piezoelectric effect and high optical transmissivity is generally deemed infeasible. Here, it is demonstrated that the ferroelectric domains in perovskite Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 domain‐engineered crystals can be manipulated by electrical field and mechanical stress to reversibly and repeatably, with small hysteresis, transform the opaque polydomain structure into a highly transparent monodomain state. This control of optical properties can be achieved at very low electric fields (less than 1.5 kV cm−1) and is accompanied by a large (>10 000 pm V−1) piezoelectric coefficient that is superior to linear state‐of‐the‐art materials by a factor of three or more. The coexistence of tunable optical transmissivity and high piezoelectricity paves the way for a new class of photonic devices.

Herein, we demonstrate photocatalytic hydrogen generation and the role of sacrificial agents using multifunctional DyCrO 3 nanoparticles by virtue of built-in electric field (BIEF) which helps in increasing charge separation efficiency. DyCrO 3 nanoparticles synthesized by the low-cost reverse micellar approach showed high surface area (17.9 m 2 / g) and band-gap (2.01 eV) in visible region. Sacrificial agent assisted photocatalytic H 2 production of DyCrO 3 nanoparticles exhibited higher selectivity towards Na 2 S/Na 2 SO 3 by produc-ing H 2 evolution of 347 μmol h À 1 g À 1 cat and apparent quantum yield of 6.8% than ethylene glycol and triethanolamine, respectively. The oxygen defects (observed in X-ray photoelectron spectroscopic studies) and BIEF both synergistically helped in enhancing photocatalytic activity. Moreover, the multifunctional competence of DyCrO 3 nanoparticles was observed in electrocatalytic water splitting. DyCrO 3 nanoparticles found to be active HER and OER electrocatalyst with low overpotential and great durability.