Dhananjay Kumar Sharma

Flexible and lightweight polymer-ceramic composites are actively pursued for mechanical energy harvesting applications. In this work, polyvinylidene fluoride (PVDF)-based composite films incorporating sol-gel synthesized (Ba,Ca)(Sn,Ti)O3 (BCST; Ba0.91Ca0.09Sn0.08Ti0.92O3) ceramic fillers were fabricated using a cost-effective solution-casting method and systematically investigated. Transmission electron microscopy (TEM) confirmed BCST particle sizes in the range of 300–600 nm. Multiscale characterization revealed a significant role of filler–polymer interfacial interactions in governing the functional properties. Microstructural and spectroscopic analyses indicate that BCST particles act as heterogeneous nucleation centers, promoting the formation of electroactive β- and γ-phases in PVDF without requiring additional treatments. The composite films exhibited enhanced dielectric permittivity while maintaining low dielectric loss, governed by dipolar and interfacial polarization mechanisms. Macroscopic ferroelectric hysteresis measurements showed improved polarization behavior, reaching a maximum polarization of ~3.8 μC/cm2 at an optimal filler concentration of 10 wt%. Nanoscale switching and piezoelectric activity were confirmed using piezoresponse force microscopy (PFM). Nanoindentation measurements revealed increased hardness and modulus, indicating improved mechanical robustness due to BCST incorporation. Under low-frequency bending excitation at a resonance frequency of ~ 4.4 Hz, the cantilever-beam-type energy harvester delivered a maximum output voltage of ~ 0.83 V and a volumetric power density of ~ 0.75 μW/cm3 for the composite with 10 wt% BCST. These results demonstrate that BCST is an effective lead-free ferroelectric filler for enhancing the functional properties of PVDF-BCST polymer composites, highlighting their potential for low-frequency, low-power energy harvesting applications.

Among the transition metal dichalcogenides, single layer MoS ₂ has drawn great attention due to its direct bandgap of approximately 1.9 eV at room temperature, exhibiting extremely high excitonic photoluminescence in the visible range, making it a promising material for opto-electronic applications. In this work, we synthesized MoS ₂ on a Si/SiO ₂ substrate using a single-step atmospheric pressure chemical vapor deposition process, successfully yielding bilayer to few layered MoS ₂ films. The layer dependence of the as-grown MoS ₂ layers was analyzed from the peak energy difference (Δ) between the in-plane (E _2g ) and out-of-plane (A _1g ) phonon modes in the Raman spectra to quantify the specific number of layers within the MoS ₂ flake (2–15 layers). Room-temperature photoluminescence characteristics of the excitonic emission exhibited a redshift in energy by 0.04 eV as the number of layers increased in MoS ₂ . An increase in the number of layers exhibited a decreasing dispersion of trion binding energy from a standardized fitting procedure of the PL spectra under appropriate boundary conditions. Henceforth, we observe a thickness dependent inversely related interplay between trion binding energy and electron density ( n ) due to defects in MoS _2, which is crucial for future opto-electronic applications.

Potassium nitrate (KNO₃) is widely utilized in concentrated solar power tower (CSPT) fuels and as an additive to address the issue of lithium dendrite formation in lithium-ion batteries and CSPT systems. This study investigates the influence of boron-doped diamond (BDD) films and their interaction with KNO₃-saturated solutions to enhance these devices’ efficiency and energy capacity. One critical factor in achieving higher energy devices is the electrochemical stability window (ESW). Consequently, this research examines various properties of BDD, including grain size, doping level, conductivity, carbon-sp³/sp² ratio, and electrolyte characteristics such as conductivity and pH. The results demonstrate that a BDD film grown at a B/C ratio of 2000 ppm, a grain size of 1.75 μm and a carbon-sp³/sp² ratio value of 0.31 achieved the broadest ESW of 3.5 V. Advantageously, the properties of the KNO₃ electrolyte, specifically concentration and pH, had minimal impact on the ESW. Controversially, the ionic conductivity of the electrolyte increased with concentration, with a peak value of 204 mS cm^–1 observed in the supersaturated solution (3.78 mol kg^–1).

Understanding how to tune the properties of electroactive materials is a key parameter for their applications in energy storage systems. This work presents a comprehensive study in tailoring polyaniline (PANI) suspensions by acid‐assisted polymerization method and their subsequent deposition on boron‐doped diamond (BDD) supports with low/high B concentrations. The porous or densely packed morphology of PANI is successfully controlled by varying the monomer‐to‐initiator ratio. The interaction between PANI and BDDs leads to the shift in oxidation and reduction potentials, and the high B doping resulted in the reduction of the oxidation potentials. Notably, the highest specific capacitance of 958 F g ⁻¹ , which represents 90% of the theoretical capacitance, is recorded for the support with relatively low B content. Moreover, PANI obtained by slow kinetic has a stronger interaction with the B‐doped diamond support, which is confirmed by electrochemical impedance spectroscopy. This study provides valuable insights for optimizing PANI suspension preparation methods and selecting appropriate boron doping concentrations in nanodiamond supports for composite electrodes in energy storage applications.

The miniaturization of electrochemical supercapacitors (EC‐SCs) requires electrode materials that are both durable and efficient. Boron‐doped diamond (BDD) films are an ideal choice for EC‐SC due to their durability and exceptional electrochemical performance. In this study, nanostructured boron‐doped ultra‐nanocrystalline diamonds (NBUNCD) are fabricated on Si micro‐pyramids (Si _P ) using a simple reactive ion etching (RIE) process. During the etching process, the high aspect ratio and the induction of sp ² graphite in these nanorod electrodes achieved a maximum specific capacitance of 53.7 mF cm ⁻² at a current density of 2.54 mA cm ⁻² , with a 95.5% retention after 5000 cycles. Additionally, the energy density reached 54.06 µW h cm ⁻² at a power density of 0.25 µW cm ⁻² . A symmetric pouch cell using NBUNCD/Si _P exhibited a specific capacitance of 0.23 mF cm ⁻² at 20 µA cm ⁻² , an energy density of 31.98 µW h cm ⁻² , and a power density of 0.91 µW cm ⁻² . These superior EC properties highlight NBUNCD/Si _P ’s potential for advancing miniaturized supercapacitors with high capacitance retention, cycle stability, and energy density.

As nanotechnology gains popularity in medicine, there is a growing concern that small nanoparticles (NPs) could accumulate and penetrate deep into the human body, posing potential risks to various organs. To ensure safe usage and assess potential hazards, it is crucial to conduct a toxicological evaluation of ZnO NPs on human organs such as the kidney. The present study involved the synthesis of ZnO NPs by using the hydrothermal method. Pure and crystalline phase was confirmed by X‐ray diffraction (XRD). The SEM images displayed less agglomerated surface morphology, implying that the NPs were distributed relatively evenly and exhibited a plate‐like shape. Two pathogenic fungi Fusarium incarnatum and Aspergillus niger were isolated from the capsicum and tomato, respectively, and identified through morphological and molecular analysis. The antimycotic property of synthesized ZnO NPs were examined against Fusariumincarnatum (MT682502) and Aspergillus niger (MT675916) and showed decreased microbial growth after 9 days of incubation. The toxicological evaluation of ZnO NPs on a human embryonic kidney (HEK293) cell line showed 88% cell viability with 10 μg/ml, leading to the safe use of ZnO NPs.