We report the intercalation and characterization of pravastatin and fluvastatin drugs in Mg(II)/Al(III) layered double hydroxides (LDHs) to form novel nanohybrid hydroxides through the coprecipitation technique. powder X-ray diffraction, Fourier transform infrared spectroscopy, and thermal analysis techniques reveal that the drugs are accommodated within the brucite layers. Structural characterization, computed results, and atomic force microscopy image analysis demonstrate that the fluvastatin anions are attached with the brucite as a monolayer, whereas the pravastatin anions form a multilayer. The shift in the stretching frequency of carboxylate anion of statin drugs provides evidence that the drugs are electrostatically bonded to LDHs. X-ray diffraction and thermal analysis studies performed after keeping the nanohybrid particles at 75 +/- 10% relative humidity atmosphere, indicate their physical stability due to proper confinement of drugs within the layers. In-vitro release study of developed nanohybrid particles suggests that the significant reduction in release rate of fluvastatin anions from fluvastatin intercalated LDHs is due to its hydrophobic nature and it can be further controlled by varying the concentration in physiological medium. After release, the data were fitted to the dissolution-diffusion kinetic model. The mechanism of drugs diffusion in hydrophobic nanohybrid is probably due to heterogeneous diffusion via anion exchange, while in a hydrophilic nanohybrid, it is due to intraparticle diffusion via anion exchange with the anions in the physiological medium.

Metal halide-based perovskites have emerged as a potential candidate for optoelectronic applications because of their impressive performance achieved by tuning the optical/electrical properties through tailoring the perovskite nanostructures. Herein, we report the synthesis of composite nanostructures by incorporation of ZnO (∼6 nm) into the CsPbBr 3 (CPB) perovskite framework, which shows significant enhancement of photocurrent because of efficient interfacial charge separation and reduced dielectric loss. Detailed steady-state and time-resolved photoluminescence studies have been carried out to understand charge transfer dynamics in the CsPbBr 3 /ZnO nanostructure composite system. Femtosecond transient absorption and broadband dielectric spectroscopy studies were carried out to determine the charge carrier relaxation and transfer mechanism. The redox energy-level diagram suggests that the photoexcited electron from the conduction band (CB) of CPB can be transferred to the CB of ZnO NP because of thermodynamic viability. Ultrafast studies reveal that the electron transfer takes place from the perovskite nanostructures to ZnO NP within ∼500 fs and limits the recombination process by efficient charge separation and charge accumulation at the interfaces. Dielectric studies also reveal reduced charge leakage in composite nanostructures with efficient charge separation by facilitating the charge accumulation at the interfaces. Overall, the efficient charge transfer and slow carrier recombination with reduced dielectric losses significantly improved the photocurrent behavior in the CsPbBr 3 /ZnO nanostructure composite system as desired for optoelectronic devices.

In-situ homogeneous dispersion of noble metals in three-dimensional graphene sheets is a key tactic for producing macroscopic architecture, which is desirable for practical applications, such as electromagnetic interference shielding and catalyst. We report a one-step greener approach for developing porous architecture of 3D-graphene/noble metal (Pt and Ag) nanocomposite monoliths. The resulting graphene/noble metal nanocomposites exhibit a combination of ultralow density, excellent elasticity, and good electrical conductivity. Moreover, in order to illuminate the advantages of the 3D-graphene/noble metal nanocomposites, their electromagnetic interference (EMI) shielding and electrocatalytic performance are further investigated. The as-synthesized 3D-graphene/noble metal nanocomposites exhibit excellent EMI shielding effectiveness when compared to bare graphene; the effectiveness has an average of 28 dB in the 8.2–12.4 GHz X-band range. In the electro-oxidation of methanol, the 3D-graphene/Pt nanocomposite also exhibits significantly enhanced electrocatalytic performance and stability than compared to reduced graphene oxide/Pt and commercial Pt/C.

Radial zinc oxide (ZnO) was prepared using a new user-friendly chemical process, and the surface was modified by adsorbing polyaniline (PANI) as a charge carrier. The modified ZnO (PZnO) was used to prepare poly(vinylidene fluoride) (PVDF)–PZnO nanocomposites with improved dielectric properties. The structural morphology of the fillers was examined using powder X-ray diffraction and then correlated with observations from high-resolution transmission electron microscopy. A new characterization technique was used to study the maximum adsorption limit by performing solvent relaxation nuclear magnetic resonance experiments, and the results suggested that a maximum of 10% PANI is adsorbed onto the ZnO. The adsorbed PANI acted as an interface and stabilized the ZnO in PVDF solution due to strong interactions between the matrix and fillers. An electron spin resonance (ESR) study was carried out to characterize the spin resonance of ZnO and PZnO. The adsorption of PANI onto ZnO generated charge carriers, and hence, under the influence of a magnetic field, the samples exhibited dissimilar resonance behavior. Dielectric studies of the PVDF–PZnO composites were performed, and the PVDF–ZnO composites and pure PVDF were compared over a wide range of frequencies (0.01 Hz–1 MHz) and temperatures (25–90 °C). The results suggest that the PVDF–7.5PZnO composite showed a significantly improved dielectric constant with a decrease in dielectric loss (0.2), most likely because the adsorption of PANI onto ZnO led to strong interactions between the matrix and fillers and enhanced the interfacial polarization in PVDF.

Developments of new and highly effective multifunctional materials have been shown great interest in recent years. Herein, we report a simple, cost efficient, one-step, surfactant-free cellular 3D-graphene/Ag nanocomposite using the freeze-casting method and explore it further for supercapacitor, catalytic, and antibacterial applications. FE-SEM and HRTEM analyses of nanocomposites revealed a 3D-cellular network structure having continuous micrometer size open pores with uniformly decorated Ag nanoparticles of an average size of 25 nm. An electrochemical study exhibited the highest specific capacitance at 845 Fg −1 at 5 mV s −1 and excellent cyclic retention ∼97% even after 1000 cycles. Further, 3D-graphene/Ag nanocomposites are applied as catalyst to reduce methylene blue using NaBH 4 . A rate of reduction above 99% was attained for 3D-graphene/Ag (40%) nanocomposites, which is significantly higher than that of pristine 3D-graphene. The network like structure of the 3D-graphene/Ag nanocomposite filtered out 37% of the population from total bacterial strains. Also, the 3D-graphene/Ag nanocomposite killed almost 100% of the bacterial strains after 3 h of incubation due to a merging effect of Ag ions and 3D-graphene.

In this study, a novel composite of Fe3O4 nanofiller-decorated single-layer graphene-assembled porous carbon (SLGAPC) with polyvinyl alcohol (PVA) having flexibility and a density of 0.75 g cm(-3) is explored for its dielectric and electromagnetic interference (EMI) response properties. The composite is prepared by the solution casting method and its constituents are optimized as 15 wt% SLGAPC and 20 wt% Fe3O4 through a novel solvent relaxation nuclear magnetic resonance experiment. The PVA-SLGAPC-Fe3O4 composite shows high dielectric permittivity in the range of 1 Hz-10 MHz, enhanced by a factor of 4 as compared to that of the PVA-SLGAPC composite, with a reduced loss by a factor of 2. The temperature dependent dielectric properties reveal the activation energy behaviour with reference to the glass transition temperature (80 °C) of PVA. The dielectric hysteresis with the temperature cycle reveals a remnant polarization. The enhanced dielectric properties are suggested to be the result of improvement in the localized polarization of the integrated interface system (Maxwell-Wagner-Sillars (MWS) polarization) formed by the uniform adsorption of Fe3O4 on the surface of SLGAPC conjugated with PVA. The EMI shielding property of the composite with a low thickness of 0.3 mm in the X-band (8.2-12.4 GHz) shows a very impressive shielding efficiency of ∼15 dB and a specific shielding effectiveness of 20 dB (g cm(-3))(-1), indicating the promising character of this material for flexible EMI shielding applications.

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