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•Same concentration of C3N and Graphene better for lowering the value of average OCV.•Charge transfer between Li and host depends on interface and site, helps to increase the ...stability and specific capacity.•Higher order structure shows the metallic behaviour.•Specific capacities in the range of 558 to 423 mAh-gm−1.•Low interlayer diffusion energy of Li-ion.
The design and development of new and light weight two-dimensional (2D) heterostructures as anode materials to enhance the electrochemical properties for Li-ion batteries (LIB’s) is a challenge. In this work, using first-principles study, we have demonstrated that the ratio of two-dimensional polyaniline (C3N) and graphene in the multilayer heterostructures plays a major role to define the Li storage properties and to provide metallicity for easy conduction of electrons. We have found that charge transfer between Li and the host depends on the interface and site, which helps in the improvement in specific capacity. The proposed heterostructures shows specific capacity varies from 558 mAh/gm to 423 mAh/gm. The specific capacity is high for heterostructures with more graphene in ratio which is correlated to higher charge accumulation in the host. Also, graphene helps to minimize the open-circuit voltage (OCV) of C3N and maintained an average of 0.4 V. The volume expansion for fully lithiated heterostructures is within 22 %. Li diffusion barrier energy varies in the range of 0.57 to 0.25 eV. The proposed 2D heterostructures could be a future material for anode in LIB’s and the description of the interface effect on Li storage properties will help for further development of 2D heterostructure materials.
In this study, we garnered three important factors simultaneously, namely, wormhole mesoporosity of TiO2 with well-designed interfaces for effective charge transfers, precise loading of MoS2 for ...plasmon induction, and increased surface area with exposed surface atoms and active sites. The controlled loading of MoS2 on porous TiO2 (MPT) forms a heterojunction that effectively modulates the interface engineering and thereby greatly enhances hydrogen evolution. The synthesis of a photocatalyst is based on a simple hydrothermal process that is well characterized. The resulting composite materials were tested for hydrogen evolution reactions. At optimum loading, MPT10 induced a maximum hydrogen evolution rate of 1376 μmol h–1 g–1 with 2.28% apparent quantum yield (AQY), which was 10-fold higher compared to the MCT10 (MoS2-commercial TiO2) H2 evolution rate of 138 μmol h–1 g–1 with 0.23% AQY under similar reaction conditions. The shorter decay component, lower emission intensity, and higher estimated lifetime of MPT10 suggest its superiority over other materials. Density functional theory (DFT) calculations have further revealed the active sites of MPT and hierarchical porous TiO2 (HPT) to support the experimental hydrogen evolution reaction (HER). This study suggests an avenue to design an efficient noble-metal-free photocatalyst for solar fuel productions.
The composition of two different categories of anode materials, i.e. layered and alloy type is the future of anode material in Li-ion batteries. In our work, using First-principles approach, we ...proposed multilayer heterostructure of graphene/graphite (layered type) with silicon monolayer (Si-ML) (origin is alloy type), as a potential anode material for LiB’s. The synergetic effect of the delocalized π electron of carbon and localized π electron of Si-ML plays a crucial role in maintaining the electron and ion conductivity increases the stability and specific capacity with moderate open circuit voltage. The model structures proposed in this work shows high specific capacities in the range of 748 to 438 mAh-gm−1. This indicates that we can tune the specific capacity using the different ratio of carbon and silicon layers. The localized π electron helps to restrict the volume expansion within 15% for a fully lithiated model structure. The low interlayer diffusion energy of Li-ion makes all the heterostructure as a potential anode material. The proposed study will help to understand the Li storage properties of the carbon/silicon based composite to develop the anode materials with a certain approach.
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•Localized π electron of Si-ML helps to increase the stability and specific capacity.•Lower the concentration of Si would be better for lowering the value of average OCV.•Specific capacities in the range of 748 to 438 mAh-gm−1.•Low interlayer diffusion energy of Li-ion.
The main challenges impeding the widespread use of organic–inorganic lead halide perovskites in modern-day technological devices are their long-term instability and lead contamination. Among other ...environmentally convivial and sustainable alternatives, Cs2SnX6 (X = Cl, Br, and I) compounds have shown promise as ambient-stable, lead-free materials for energy harvesting, and optoelectronic applications. Additionally, they have demonstrated tremendous potential for the fabrication of self-powered nanogenerators in conjunction with piezoelectric polymers like polyvinylidene-fluoride (PVDF). We report on the fabrication of composites constituting solvothermally synthesized Cs2SnX6 nanostructures and PVDF. The electroactive phases in PVDF were boosted by the incorporation of Cs2SnX6, leading to enhanced piezoelectricity in the composites. First-principles density functional theory (DFT) studies were carried out to understand the interfacial interaction between the Cs2SnX6 and PVDF, which unravels the mechanism of physisorption between the perovskite and PVDF, leading to enhanced piezoresponse. The halide ions in the inorganic Cs2SnX6 perovskites were varied systematically, and the piezoelectric behaviors of the respective piezoelectric nanogenerators (PENGs) were investigated. Further, the dielectric properties of these halide perovskite-based hybrids are quantified, and their piezoresponse amplitude, piezoelectric output signals, and charging capacity are also evaluated. Out of the several films fabricated, the optimized Cs2SnI6_PVDF film shows a piezoelectric coefficient (d 33) value of ∼200 pm V–1 and a remanent polarization of ∼0.74 μC cm–2 estimated from piezoresponse force microscopy and polarization hysteresis loop measurement, respectively. The optimized Cs2SnI6_PVDF-based device produced an instantaneous output voltage of ∼167 V, a current of ∼5.0 μA, and a power of ∼835 μW across a 5 MΩ resistor when subjected to periodic vertical compression. The output voltage of this device is used to charge a capacitor with a 10 μF capacitance up to 2.2 V, which is then used to power some commercial LEDs. In addition to being used as a pressure sensor, the device is employed to monitor human physiological activities. The device demonstrates excellent operational durability over a span of several months in an ambient environment vouching for its exceptional potential in application to mechanical energy harvesting and pressure sensing applications.
The main challenges impeding the widespread use of organic-inorganic lead halide perovskites in modern-day technological devices are their long-term instability and lead contamination. Among other ...environmentally convivial and sustainable alternatives, Cs
SnX
(X = Cl, Br, and I) compounds have shown promise as ambient-stable, lead-free materials for energy harvesting, and optoelectronic applications. Additionally, they have demonstrated tremendous potential for the fabrication of self-powered nanogenerators in conjunction with piezoelectric polymers like polyvinylidene-fluoride (PVDF). We report on the fabrication of composites constituting solvothermally synthesized Cs
SnX
nanostructures and PVDF. The electroactive phases in PVDF were boosted by the incorporation of Cs
SnX
, leading to enhanced piezoelectricity in the composites. First-principles density functional theory (DFT) studies were carried out to understand the interfacial interaction between the Cs
SnX
and PVDF, which unravels the mechanism of physisorption between the perovskite and PVDF, leading to enhanced piezoresponse. The halide ions in the inorganic Cs
SnX
perovskites were varied systematically, and the piezoelectric behaviors of the respective piezoelectric nanogenerators (PENGs) were investigated. Further, the dielectric properties of these halide perovskite-based hybrids are quantified, and their piezoresponse amplitude, piezoelectric output signals, and charging capacity are also evaluated. Out of the several films fabricated, the optimized Cs
SnI
_PVDF film shows a piezoelectric coefficient (
) value of ∼200 pm V
and a remanent polarization of ∼0.74 μC cm
estimated from piezoresponse force microscopy and polarization hysteresis loop measurement, respectively. The optimized Cs
SnI
_PVDF-based device produced an instantaneous output voltage of ∼167 V, a current of ∼5.0 μA, and a power of ∼835 μW across a 5 MΩ resistor when subjected to periodic vertical compression. The output voltage of this device is used to charge a capacitor with a 10 μF capacitance up to 2.2 V, which is then used to power some commercial LEDs. In addition to being used as a pressure sensor, the device is employed to monitor human physiological activities. The device demonstrates excellent operational durability over a span of several months in an ambient environment vouching for its exceptional potential in application to mechanical energy harvesting and pressure sensing applications.
The use of smartphone is increasing day by day for personal as well as professional purpose. They are becoming a more suitable tool for advancing education in developing countries. Mobile access to ...information and many applications are successfully harnessed in health care. Smartphones are also becoming popular as an effective educational tool.
The present study was conducted to evaluate the use of smartphones as an educational tool amongst the medical students. The study also aimed at identifying the common medical application used by the students.
It was an observational cross-sectional study carried out amongst medical students of private medical institute in India. A validated 16 point, structured, open-ended, questionnaire regarding ownership and use of smart phones was self-administered to 446 medical students. Data were analysed using SPSS and open ended questions were analysed by summative content analysis.
Among the study population, 96% owned a smartphone -Android based 72.4%, i phone 13.0%, Windows based Nokia phones 7% and Blackberry 3.6%. Common medical applications used by the students were Anatomy and Medical Dictionary in First MBBS; Medical Dictionary, Medscape and Google/Wikipedia in Second MBBS; and Medscape, Google/Wikipedia and Prognosis/Diagnosis in Third MBBS. More than 90% students, reported to have technological skills to use smartphones, for medical education, communication and instant access during bedside teaching. Advertently, 37.2% students felt if smartphones are used for clinical purposes, they will need to spend less time with patients. Almost 79.4% felt that smartphones should be introduced in MBBS course.
Smartphone use amongst medical students as learning aid for various medical applications is rapidly advancing. But it will be worthwhile to study whether use of smartphones has any impact on the grades of the students before introducing them in medical schools.
Defect engineering through modification of their surface linkage is found to be an effective pathway to escalate the solar energy conversion efficiency of metal-organic frameworks (MOFs). Herein, ...defect engineering using controlled decarboxylation on the NH2-UiO-66 surface and integration of ultrathin NiCo-LDH nanosheets synergizes the hydrogen evolution reaction (HER) under a broad visible light regime. Diversified analytical methods including positron annihilation lifetime spectroscopy were employed to investigate the role of Zr3+-rich defects by analyzing the annihilation characteristics of positrons in NH2-UiO-66, which provides a deep insight into the effects of structural defects on the electronic properties. The progressively tuned photophysical properties of the NiCo-LDH@NH2-UiO-66-D-heterostructured nanocatalyst led to an impressive rate of HER (∼2458 μmol h-1 g-1), with an apparent quantum yield of ∼6.02%. The ultrathin NiCo-LDH nanosheet structure was found to be highly favored toward electrostatic self-assembly in the heterostructure for efficient charge separation. Coordination of Zr3+ on the surface of the NiCo-LDH nanosheet support through NH2-UiO-66 was confirmed by X-ray absorption spectroscopy and electron paramagnetic resonance spectroscopy techniques. Femtosecond transient absorption spectroscopy studies unveiled a photoexcited charge migration process from MOF to NiCo-LDH which favorably occurred on a picosecond time scale to boost the catalytic activity of the composite system. Furthermore, the experimental finding and HER activity are validated by density functional theory studies and evaluation of the free energy pathway which reveals the strong hydrogen binding over the surface and infers the anchoring effect of the ultrathin layered double hydroxide (LDH) in the vicinity of the Zr cluster with a strong host-guest interaction. This work provided a novel insight into efficient photocatalysis via defect engineering at the linker modulation in MOFs.
BiFeO3-based composite materials are important due to their versatile multiferroic properties which can be further tuned upon doping. 0.5BiNdxFe1-xO3-0.5PbZrO3 (x = 0.05, 0.1, and 0.2) ...polycrystalline ceramic samples were prepared by solid-state reaction technique at high temperature. X-ray diffraction (XRD) and Rietveld refinement process confirm the presence of mainly rhombohedral (R3c) phase. Dielectric studies reveal the presence of Maxwell-Wagner type polarization. Electric impedance and modulus values of the samples were studied over a wide range of temperature and frequency. Complex impedance and modulus studies shows the presence of non-Debye type of relaxation in the materials. ac conductivity results can be fitted with Jonscher's power law and indicates the dominance of correlated barrier hopping mechanism in charge transport. Furthermore, density of states calculated from ac conductivity shows variation as a function of dopant content which is further corroborated from density functional theory-based results.
•Synthesis of Nd-doped BFO-PZO composites.•Rietveld refinement confirming rhombohedral (R3c) phase.•Complex impedance spectroscopy for understanding conduction mechanism.•CBH model for conduction, DOS, and hopping length calculation.•Bader charge calculation with Nd doping using DFT.
Trirutile NiTa2O6 has been studied under high pressure by in situ Raman and angle-dispersive synchrotron X-ray diffraction techniques. It undergoes a new quenchable phase at high pressures above 11.8 ...GPa accompanied by softening of the internal modes ν1(A1g), ν1(Eg), and ν6(Eg), and it is denser by 15% compared with its ambient phase. Various Raman-active modes of NiTa2O6 diminished at high pressures due to the distortion of edge-sharing TaO6 octahedra, which was further confirmed by X-ray diffraction and density functional theory results. The equation of state has been determined using the second-order Birch–Murnaghan equation, and the obtained bulk modulus is 199(4) GPa. The pressure and volume dependence of optical lattice vibrational frequencies and their corresponding Grüneisen parameters are calculated, indicating the inconsistency of the trirutile structure at high pressures, which was accompanied by the strong deformation of TaO6 octahedra. Pressure-induced structural metamorphosis and soft-mode-driven displacive transition related to the mechanical instability of NiTa2O6 are examined and decompression results recommend the transition is irreversible.
Widely used precious metal (i.e., Pt, or Pd) electrocatalysts need to be replaced with other cost-effective and earth-abundant materials for economical water splitting applications. Recently, ...two-dimensional (2D) transition metal dichalcogenides (MoS2, VS2, WS2, etc.) have emerged as ideal electrocatalysts for the hydrogen evolution reaction (HER) due to their tunable physicochemical properties and rich catalytic active sites. In this regard, we propose a strategy to achieve improved HER performance of VS2 by fabricating a hybrid material with transition metal (Zn and Cd)-based sulfides. A facile hydrothermal approach is employed to prepare a VS2/ZnS/CdS hybrid catalyst that exhibits remarkable electrocatalytic performance for the HER in acidic media with a small overpotential of 86 mV at 10 mA/cm2 and a Tafel slope of 74.4 mV/dec. This inferred the Volmer–Heyrovsky mechanism with electrochemical desorption of hydrogen as the rate-limiting step. High performance is attributed to the abundance of catalytically active sites and the synergistic interactions between the materials. Theoretical calculations reveal that the VS2/ZnS/CdS hybrid shows favorable HER activity owing to its low hydrogen adsorption free energy of about 0.35 eV. We believe that this work on designing 2D VS2/ZnS/CdS will offer a new pathway to discover an efficient H2 generation electrocatalyst.
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