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•Synthesis of Polyaniline/graphene nanocomposites by simple chemical method.•Analysis of Electromagnetic shielding effectiveness.•Superior Shielding effectiveness (64 dB) with ...polyaniline/graphene nanocomposite.•Detailed analysis of dielectric properties of polyaniline/graphene nanocomposite.
Polyaniline (PANI) and its nanocomposites with graphene have been synthesized using simple chemistry based method and are utilized to mitigate the problem of electromagnetic pollutions in high-frequency range (X-band: 8.2–12.4 GHz) of the microwave region. The PANI/graphene nanocomposites showed total shielding effectiveness as high as 64 dB with 8 wt% loading of graphene in PANI. The EMI shielding effectiveness via absorption for all the samples dominates over the reflective part due to high dielectric losses in bulk of sample. The enhancement in shielding effectiveness properties are occurred due to strong polarization, charge propagation and formation of conducting pathways due to encapsulation of graphene in PANI. Moreover, the high dielectric losses (ɛ″ ≈ 35–175) and total ac conductivities (σm ≈ 11–102 S/m) contribute in enhanced shielding effectiveness. The very high values of shielding effectiveness for these samples make them suitable materials for industrial as well as defense/aerospace applications.
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•Growth of single crystalline Zn0.98X0.02O (X = Fe, Ga, Ni) Thin Films by PLD Technique.•Diluted magnetic semiconducting (DMS) properties of doped ZnO Thin Films.•Systematic Analysis ...of mechanism of magnetic behavior of ZnO thin films.
Structural, optical and diluted magnetic semiconducting properties of pristine ZnO, Fe-doped (Zn0.98Fe0.02O), Ga-doped (Zn0.98Ga0.02O) and Ni-doped (Zn0.98Ni0.02O) ZnO thin films deposited by pulsed laser deposition technique have been studied. X-ray diffraction (XRD) studies reveal the nanocrystalline nature in single wurtzite phase of all the films. Optical bandgap of the films found to depend upon the transition/post-transition metal doping and has a maximum value (∼3.65 eV) for Zn0.98Ga0.02O film and lowest value (∼3.23 eV) for Zn0.98Ni0.02O film. SQUID-vibrating sample magnetometer studies confirm the ferromagnetic nature of all the films with well defined field dependent magnetization (M−H) curves and temperature dependent zero field cooled (ZFC) and field cooled (FC) curves. The origin of ferromagnetism in the present films has been analyzed under bound magnetic polarons (BMPs) and grain boundary specific area models. The present films are found to follow the grain boundary specific area model for the origin of ferromagnetism.
Ammonia, a ubiquitous gas with diverse industrial applications, demands reliable and cost-effective sensing technologies for monitoring and control. In this context, this study presents the ...development of a novel ternary nanocomposite comprised of porous polyaniline (PANI), hybrid phase molybdenum disulfide (MoS2), and phosphorus-doped graphene (PGO) for the realization of highly efficient room temperature ammonia sensors. The synergistic combination of these three materials leverages their individual properties, such as high surface area, excellent electrical conductivity, and enhanced catalytic activity, to create a robust sensing platform. The PANI/1 T-2 H MoS2/PGO nanocomposites were synthesized by a combination of solvothermal processing and in-situ polymerization techniques. The morphological and structural characteristics of the PANI/1 T-2 H MoS2/PGO nanocomposites were conducted using advanced analytical techniques, that include, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Raman spectroscopy, Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS), and Brunauer-Emmett-Teller method (BET). The enhanced surface area of PANI/1 T-2 H MoS2/PGO (54.72 m2/g) compared to PANI (31.8 m2/g) has a positive impact on the sensing characteristics of PANI/1 T-2 H MoS2/PGO. The PANI/1 T-2 H MoS2/PGO nanocomposite sensor has shown sensing response values of ∼1070 %, response time of 12 s, recovery time of 30 s towards 100 ppm of NH3, and detection limit is 0.01 ppm (10 ppb). A highly linear gas response of the PANI/1 T-2 H MoS2/PGO sensor is observed in a range of 10–100 ppm ammonia concentration. The development of the PANI/1 T-2 H MoS2/PGO nanocomposite sensor aims to meet the increasing need for temperature-efficient, cost-effective, and energy-efficient gas sensing technologies that can be used in various fields including environmental monitoring and industrial safety.
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•1T-2H MoS2 /PGO composite was synthesized by solvothermal approach.•Novel PANI/1T-2HMoS2/PGO composite synthesized by in-situ polymerization method.•The sensor has shown sensing response ∼1070 %, detection limit of 10 ppb.•Response time 12 s and recovery time 30 s.•The synthesized composite showed excellent sensitivity toward NH3 vapors.
The effect of ambient environment on the temperature-dependent space charge-limited current conduction behavior of the n-ZnO/p-Si
++
hetero-junction device has been reported. The nanocrystalline ZnO ...thin film has been deposited by simple thermal evaporation technique on the heavily doped p-type silicon substrate. The crystalline structural analysis of the deposited thin film has been carried out using x-ray diffraction (XRD) studies. The crystallite size, lattice parameter ‘
c
,’ stress, and strain estimated through XRD studies are found to have values of 22.50 nm, 5.25 Å, 2.14 × 10
−3
Pa, and 1.60 × 10
−3
, respectively. The surface morphological analysis has been done through field emission scanning electron microscopy, which reveals the distribution of ZnO nanoparticles of size ~ 110 nm on the surface film. The mechanism of charge transport in the fabricated n-ZnO/p-Si
++
hetero-junction device has been analyzed through current–voltage characteristics recorded at different operating temperatures in the range from 298 to 423 K in air and hydrogen ambient environments. A trap states-assisted space charge-limited current conduction mechanism has been observed for the fabricated hetero-junction device both in the air as well as in hydrogen environments. The reduction of rectification ratio from ~ 40.05 to 1.75 in air ambient and from 187.10 to 5.82 in hydrogen ambient environment, and reduction of ideality factor from 2.848 to 2.513 and increase of junction potential from 0.384 to 0.403 eV with increasing the device operating temperature from 298 to 423 K further support the trap states-assisted current conduction in the fabricated hetero-junction device.
Ni-doped ZnS nanoparticles are synthesized by simple hydrothermal process for the utilization in UV photodetectors. Surface morphology of the prepared samples is investigated through high resolution ...transmission electron microscopy (HRTEM), which reveals that the prepared nanoparticles are smaller than 20 nm. The well visualized selected area electron diffraction rings suggests the nanocrystalline nature of the prepared nanoparticles with (hkl) planes (111), (220) and (311). The structural analysis is done by x-ray diffraction (XRD) studies; which reveal the decrease in crystallite size with increase in Ni-doping concentration. The device performance of the photodetectors is tested under UV-A light (wavelength ≈365 nm) and found that the ability of the prepared devices increases with increase in Ni-doping concentration. This can be attributed to the enhanced surface to volume ratio and increase in charge carrier concentration. The adsorption-desorption of oxygen molecules on the nanoparticles' surface is considered to be the mechanism for UV photodetection.
•Synthesis of Ni-doped ZnS Nanoparticles.•Effect of Ni-doping on UV photodetection ability of ZnS nanoparticles.•Understanding UV photodetection mechanism through oxygen adsorption/desorption.
Polypyrrole (PPy) nanoparticles have been synthesized by chemical oxidation method in the presence of anionic surfactant (sodium dodecyl sulphate). The prepared nanoparticles have a diameter of ...~28 nm. The low-frequency and temperature-dependent dielectric properties of these nanoparticles have been studied in the temperature range of 77-350 K. Due to absence of the saturated loss peaks, modulus approach has been used for the further insight on the dielectric properties of prepared nanoparticles. The behaviour of the dielectric modulus suggests the Debye-type behaviour of the prepared nanoparticles, where the measured ac conductivity follows the classical hopping conduction mechanism.
In the present study, we report the fabrication of n-ZnO/p-Si
++
hetero-junction devices for the detection of hydrogen leakage in ambient air environment. For the fabrication of n-ZnO/p-Si
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...hetero-junction devices, high quality ZnO thin films are grown by controlled thermal evaporation technique on the highly doped p-type silicon substrates at 400
o
C. The two sets of films deposited at 400
o
C are further annealed at 500 and 600
o
C to examine the effect of annealing temperature on the structural, morphological, electrical and gas sensing properties of the deposited films. It is revealed from the x-ray diffraction studies that the crystallite size, and the density of the films increase from 22.55 to 24.95 nm, and from 5.65 to 5.68 g/cm
3
, respectively, on increasing the fabrication temperature from 400 to 600
o
C. In contrast to this, the grain boundary specific surface area decreases from 8.79 × 10
7
to 7.88 × 10
7
m
−1
on changing the fabrication temperature from 400 to 600
o
C. The hydrogen gas sensing responses of the fabricated devices have also been recorded at different operating temperatures and different hydrogen concentrations (200 to 1000 ppm) in air ambient. It is found that the gas sensing responses of the fabricated devices increase with increase in operating temperature up to 100
o
C and decease beyond this temperature. The gas sensing responses of the devices fabricated at 400, 500 and 600
o
C are found to be 97.22, 64.23 and 40.77 % respectively at 1000 ppm of hydrogen. A decrease in gas sensing response with fabrication temperature is attributed to the increase in crystallite size (quantum size effect), density of film (i.e. lower penetration) and decrease in grain boundary specific surface area (i.e. active sites) with annealing temperature. The mechanism of the gas sensing in these devices has also been systematically analyzed under different models.
Polypyrrole (PPy) nanomaterials have been synthesized with varying concentrations (10–40 mM) of anionic surfactant camphor sulphonic acid (CSA) using the chemical polymerization method, and then ...utilized for electromagnetic interference (EMI) shielding applications in the X-band of the microwave frequency range (8.2–12.4 GHz). An observable systematic change in the morphology of the prepared PPy has been noted, with highly aggregated globules transforming into fibular-like structures with an average diameter of approximately 80–120 nm as the CSA concentration increased. Raman and Fourier-transform infrared (FTIR) measurements indicate an increase in the relative intensities of the bipolaronic to polaronic bands, suggesting an improved conjugation of PPy with increasing CSA concentration. The electrical conductivity at room temperature has also been found to increase significantly, from 2.55 S/cm to 35.80 S/cm, as the concentration of CSA surfactant increased from 10 mM to 40 mM. Additionally, the shielding effectiveness (SE) for reflection (SE
R
), SE for absorption (SE
A
), and total SE (SE
T
) have been found to increase with increasing CSA concentration in PPy. The SE
T
values have been found exceeding 35 dB throughout the X-band of the microwave region in PPy nanomaterials with CSA concentrations ≥ 20 mM. It has been observed that CSA-directed polypyrrole exhibits high electrical conductivity, where the SE for absorption (SE
A
) dominates over the SE for reflection (SE
R
). This study suggests that the properties of PPy can be easily tailored for its potential utilization in the fabrication of various EMI shielding devices with improved performance.
In the present study, polyaniline (PAni) thin films have been deposited on glass substrates by in-situ chemical polymerization method using simple dip-coating technique and their opto-electrical ...properties have been studied. The structure of deposited films have been analysed with Fourier transform infrared (FTIR) and Raman spectroscopic techniques to investigate the effect of deposition times on the conjugation length, polaron/bipolaron concentrations and other molecular structure conformations. FTIR and Raman spectroscopy studies reveal increase in both the conjugation length and the polaron/bipolaron carrier concentration with increasing deposition time of the prepared PAni films. The optical properties and optical band-gap of the deposited films have been estimated through UV–visible spectroscopy. The optical band-gap of the deposited films has been found to decrease from 3.31 eV to 3.13 eV with increase in deposition time from 1.5 h to 2.5 h, and further it has been increased slightly to 3.19 eV for the PAni film deposited for 3 h. The electrical conductivity of the deposited films has been found to increase with decrease in optical band gap. The parameters estimated from FTIR, Raman, UV–visible spectroscopy and electrical measurements are in good agreement with each other. It has been observed that the optical and electrical properties of the deposited films depend on the conjugation length of PAni. The polymerization time of 2.5 h has been found to be optimum for obtaining PAni thin films with good electrical conductivity and low optical band gap.
•Polyaniline (PAni) thin films have been grown on glass substrates using in-situ polymerization method for different dipping times.•The effect of polymerization time on optical, electrical and structural properties of the PAni films has been investigated.•Observed optical and electrical properties have been well correlated to the induced structural changes of the PAni films.•Such opto-electrical behaviour suggest the possible utilization of prepared PAni films for various opto-electronic devices.
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•PNGN was synthesized by hydrothermal approach.•PANI/PNGN 15% composite synthesized by in-situ polymerization method.•The sensor has shown sensing response ∼810 %, detection limit of ...0.012 ppm.•Response time and recovery time are 21 s and 56 s.•PANI/PNGN 15% exhibits a remarkable specific capacitance of 750.41 F g−1 at 5 Ag−1.
In the pursuit of developing advanced materials with multifunctional capabilities, the integration of polymers and graphene-based materials has garnered significant attention. In the quest for the synergy between polyaniline (PANI) and phosphorus, nitrogen dual co-doped graphene (PNGN) has emerged as a promising avenue for multifunctional applications in supercapacitors and gas sensing devices. The PANI/PNGN 15 % nanocomposites were synthesized by a combination of hydrothermal processing and in-situ polymerization techniques. The synthesized nanocomposites were characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies. The PANI/PNGN 15 % nanocomposite sensor has shown sensing response values of ∼810 %, the response time of 21 s, recovery time of 56 s, and a detection limit of 0.082 ppm. The PANI/PNGN 15 % nanocomposite achieved a remarkable specific capacitance of 750.41 F g−1 at a current density of 5 A g−1. Moreover, the symmetrical supercapacitor exhibits remarkable rate capability, achieving (∼82.14 % at 5 Ag−1), while also maintaining excellent cycling stability. The synergistic effects of PANI and PNGN contribute to the development of high-performance devices, paving the way for advancements in the fields of supercapacitors and gas sensing technologies.
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