Maryam Bonyani - Academia.edu (original) (raw)

Papers by Maryam Bonyani

Processing and Application of Ceramics, 2016

The extensive use of piezoelectric ceramics such as lead zirconate titanate (PZT) in different ap... more The extensive use of piezoelectric ceramics such as lead zirconate titanate (PZT) in different applications became possible with the development of donor or acceptor dopants. Therefore, studies on the effect of dopants on the properties of PZT ceramics are highly demanded. In this study undoped and 2.4 mol% Nb-doped PZT (PZTN) powders were successfully obtained by a solid-state reaction and calcination at 850°C for 2 h. Crystallinity and phase formation of the prepared powders were studied using X-ray diffraction (XRD). In order to study morphology of powders, scanning electron microscopy (SEM) was performed. The crystalline PZT and Nb-doped PZT powders were pelleted into discs and sintered at 1100, 1150 and 1200°C, with a heating rate of 10°C/min, and holding time of 1-6 h to find the optimum combination of temperature and time to produce high density ceramics. Microstructural characterization was conducted on the fractured ceramic surfaces using SEM. Density measurements showed that maximal density of 95% of the theoretical density was achieved after sintering of PZT and PZTN ceramics at 1200°C for 2 h and 4 h, respectively. However, the results of dielectric measurements showed that PZTN ceramics have higher relative permittivity (ε r ∼17960) with lower Curie temperature (∼358°C) relative to PZT (ε r = 16000 at ∼363°C) as a result of fine PZTN structure as well as presence of vacancies. In addition, dielectric loss (at 1 kHz) of PZT and PZTN ceramics with 95% theoretical density was 0.0087 and 0.02, respectively. The higher dielectric loss in PZTN was due to easier domain wall motions in PZTN ceramics.

Chemosensors

Ternary systems are less studied for sensing applications due to complex synthesis procedures. Ho... more Ternary systems are less studied for sensing applications due to complex synthesis procedures. However, they have more sources of resistance modulation, leading to an enhanced gas response. In this study, a ternary system, namely Au-decorated ZnO-polyaniline (PANI) composite nanofibers with different amounts of PANI (10, 25, and 50 wt.%) were synthesized for NO2 gas sensing studies. First, ZnO nanofibers were synthesized by electrospinning, and then an Au layer (9 nm) was coated on the ZnO nanofibers. Finally, PANI was coated onto the prepared Au-decorated ZnO nanofibers. NO2 gas sensing investigations indicated that the sensor with 25 wt.% PANI had the best response to NO2 gas at 300 °C. In addition, the optimized sensor exhibited high selectivity to NO2 gas. The improved performance of the optimal gas sensor was attributed to the role of Au, the formation of ZnO-PANI heterojunctions, and the optimal amount of PANI. The promising effect of this ternary system for NO2 sensing was de...

Sensors and Actuators B: Chemical

Lecture Notes in Electrical Engineering, 2017

In this paper is reported the development of microstrip resonators working in the frequency range... more In this paper is reported the development of microstrip resonators working in the frequency range of 3–6 GHz and their employment in the investigation of the sensing properties of nanostructured materials towards gas. The materials are deposited as films on the gap of the resonators by drop coating aqueous solutions of Ag@α-Fe2O3 nanocomposite having a core–shell structure. Here are reported sensing data about humidity monitoring in the range from 0 to 70%. The increase of humidity value brings to a large frequency shift of the resonance one. The good characteristics of the fabricated device suggest its promising use as humidity sensor.

In this paper, stable water solution using a Pechini sol-gel process was prepared. The solution w... more In this paper, stable water solution using a Pechini sol-gel process was prepared. The solution was used for the direct printing of iron oxide precursor on alumina substrates. To convert the precursor to the desired iron oxide phase, an annealing step was carried out at elevated temperatures (>450 °C). In this work a α-Fe2O3 thin film-based chemoresistive sensors for ethanol detection in air were fabricated. The device developed was investigated for evaluate the sensing characteristics such sensitivity, selectivity and stability.

TrAC Trends in Analytical Chemistry, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Asian Journal of Atmospheric Environment, 2020

Resistive-based gas sensors built through the combination of semiconducting metal oxides and cond... more Resistive-based gas sensors built through the combination of semiconducting metal oxides and conducting polymers (CPs) are widely used for the detection of diverse gaseous components. In light of the great potential of each of these components, electrospun CPs produced by a facile electrospinning method can offer unique opportunities for the fabrication of sensitive gas sensors for diverse gaseous compounds due to their large surface area and favorable nanomorphologies. This review focuses on the progress achieved in gas sensing technology based on electrospun CPs. We offer numerous examples of CPs as gas sensors and discuss the parameters affecting their sensitivity, selectivity, and sensing mechanism. This review paper is expected to offer useful insights into potential applications of CPs as gas sensing systems.

International Journal of Hydrogen Energy, 2019

Hydrogen has captured a lot of attention in recent years because its abundance, cleanness and one... more Hydrogen has captured a lot of attention in recent years because its abundance, cleanness and one of the most promising sources of green energy. However, hydrogen has an explosive nature. Accordingly, detection of hydrogen leaks is important from a safety point of view. In this review paper, we use numerous examples to explain how Pd-decoration on the surfaces of nanomaterials can lead to enhancements in response and selectivity toward hydrogen gas. First, we describe the importance of hydrogen detection, then the properties of Pd and PdH x are reviewed, and metallic Pd hydrogen gas sensors are discussed. Finally, we comprehensively review different semiconducting gas sensors decorated with Pd with more emphasis on the sensing mechanism. This review paper provides a simple yet informative background for researchers working in this hot field.

Optik, 2018

ZnO/reduced graphene oxide (RGO) heterostructures were fabricated using a simple two-step wet che... more ZnO/reduced graphene oxide (RGO) heterostructures were fabricated using a simple two-step wet chemical technique and post-annealing treatment. ZnO nanoparticles with different sizes (20-200 nm) and shapes were randomly distributed on mono-and/or multilayered RGO sheets. The microstructures of the ZnO/RGO composites examined using transmission electron microscopy indicated that the heterostructures are polycrystalline in nature, implying the possibilities of diverse defects present in the samples. The photoluminescence spectra examinations revealed the enhancement of defect-level emission peaks observed at a relatively long wavelength ranges (i.e., 779 nm, 666 nm, and 574 nm) as compared with the band to band transition observed at relatively short wavelengths (i.e., 378 nm).

Current Applied Physics, 2018

MoO 3 eZnO coreeshell nanorods were synthesized by a simple two-step process. MoO 3 nanorods were... more MoO 3 eZnO coreeshell nanorods were synthesized by a simple two-step process. MoO 3 nanorods were synthesized by a hydrothermal method, which was followed by atomic layer deposition of a ZnO shell. The phase and crystallinity of the synthesized products were examined by X-ray diffraction, and the morphological features were studied by scanning electron microscopy. Gas sensing tests were performed on both pristine MoO 3 nanorods and MoO 3 eZnO coreeshell nanorods. Sensors containing the pristine MoO 3 nanorods and MoO 3 eZnO coreeshell nanorods showed responses (R a /R g where R a and R g are the electrical resistances of the sensors in air and the target gas, respectively) of 1.15 and 7.6, respectively, to 200 ppm ethanol at 350 C. Therefore, the response of the MoO 3 eZnO coreeshell nanorod sensors to ethanol gas was significantly better than that of pristine MoO 3 nanorods. The underlying mechanisms for the enhanced sensing performance are discussed in detail.

Applied Surface Science, 2017

Highlights  Pristine WO3 nanorods and Cr2O3-functionalized WO3 nanorods were synthesized.  The ... more Highlights  Pristine WO3 nanorods and Cr2O3-functionalized WO3 nanorods were synthesized.  The Cr2O3-functionalized WO3 nanorod sensor showed a stronger response to these gases than the pristine WO3 nanorod sensor.  The former sensor showed a shorter response and recovery time than the latter one.  The Cr2O3-functionalized WO3 nanorods sensor showed good selectivity toward ethanol.  The underlying mechanisms for the enhanced sensing performance of the functionalized sensor are discussed in detail.

Chemosensors, 2016

The development of an electrochemical dissolved oxygen (DO) sensor based on a novel Cu(II) comple... more The development of an electrochemical dissolved oxygen (DO) sensor based on a novel Cu(II) complex-modified screen printed carbon electrode is reported. The voltammetric behavior of the modified electrode was investigated at different scan rates and oxygen concentrations in PBS (pH = 7). An increase of cathodic current (at about´0.4 vs. Ag/AgCl) with the addition of oxygen was observed. The modified Cu(II) complex electrode was demonstrated for the determination of DO in water using chronoamperometry. A small size and low power consumption home-made portable electrochemical analyzer based on custom electronics for sensor interfacing and operating in voltammetry and amperometry modes has been also designed and fabricated. Its performances in the monitoring of DO in water were compared with a commercial one.

Measurement, 2016

Abstract AgNPs/PMA hybrid nanocomposite materials with different Ag loadings have been synthesize... more Abstract AgNPs/PMA hybrid nanocomposite materials with different Ag loadings have been synthesized using a simple chemical route assisted by UV irradiation. The hybrid composites were characterized by means of SEM and TEM, UV–vis spectroscopy and XPS. The as synthesized hybrid samples, composed of small Ag nanoparticles (AgNPs) embedded within the PMA (poly-methacrylic-acid) matrix, have been used to modify the working electrode of disposable screen printed carbon electrodes (SPCEs). It has been observed that hybrid composite with the lowest Ag loading forms dendritic silver structures on the surface of working electrode, whereas at higher loadings massive structures were formed. The electrocatalytic properties of the AgNPs/PMA/SPCEs were investigated toward the reduction of nitrate at neutral pH. Based on these modified electrodes, both voltammetric and amperometric sensors were developed for the electrochemical sensing of nitrate. Voltammetric sensor showed a wide linear range (0–20 mM) and high sensitivity (130 μA mM −1 cm −2 ).

Ceramics International, 2016

Abstract In the present work, α-Fe2O3 nanoparticles were successfully synthesized by Pechini sol–... more Abstract In the present work, α-Fe2O3 nanoparticles were successfully synthesized by Pechini sol–gel (PSG) method following annealing at 550 °C. The morphology and microstructure of the prepared α-Fe2O3 nanoparticles were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman analysis. The electrical and sensing properties were also investigated. The α-Fe2O3 based sensor showed good sensitivity and selectivity towards ethanol at the optimal temperature of 225 °C. Moreover, the sensor displayed good electrical and sensing stability. These results suggest the potential applications of α-Fe2O3 synthesized by Pechini sol–gel method as a sensor material for ethanol detection.

Journal of Nanoscience and Nanotechnology, 2017

Journal of Nanostructure in Chemistry, 2016

In this study, the size-controlled synthesis of silver nanoparticles (Ag NPs) via chemical reduct... more In this study, the size-controlled synthesis of silver nanoparticles (Ag NPs) via chemical reduction method by NaBH 4 as a reducing agent and poly(vinyl pyrrolidone) or PVP as a stabilizing agent is reported. Changing of ratios between reducing agent and stabilizing agent relative to AgNO 3-optimized conditions for synthesis of stable Ag NPs was studied. The formation of Ag NPs was tracked by UV-Vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. Particle size distribution was studied by particle size analyzer, and the morphology was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical properties of the synthesized Ag NPs were also investigated. The optimized Ag NPs were very stable even after 1 month that was due to effective stabilization by PVP molecules. The mechanism of Ag NPs formation and stabilization is discussed in detail.

Ceramics International, 2016

Abstract In this communication, Ag/Fe 2 O 3 nanocomposites were successfully synthesized by reduc... more Abstract In this communication, Ag/Fe 2 O 3 nanocomposites were successfully synthesized by reduction of silver nitrate with NaBH 4 and subsequent coating of Fe 2 O 3 by a simple Pechini sol-gel method. Synthesized powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Gas sensing properties of Ag/Fe 2 O 3 nanocomposites and pristine Fe 2 O 3 were studied at different temperature and in the presence of different gases. It was found that Ag/Fe 2 O 3 sensor even can detect 500 ppb NO 2 gas at 150 °C, whereas pristine Fe 2 O 3 sensor showed no significant response to NO 2 . The possible mechanisms of NO 2 sensing by Ag/Fe 2 O 3 are discussed in detail.

IOP Conference Series: Materials Science and Engineering, 2015

Processing and Application of Ceramics, 2016

The extensive use of piezoelectric ceramics such as lead zirconate titanate (PZT) in different ap... more The extensive use of piezoelectric ceramics such as lead zirconate titanate (PZT) in different applications became possible with the development of donor or acceptor dopants. Therefore, studies on the effect of dopants on the properties of PZT ceramics are highly demanded. In this study undoped and 2.4 mol% Nb-doped PZT (PZTN) powders were successfully obtained by a solid-state reaction and calcination at 850°C for 2 h. Crystallinity and phase formation of the prepared powders were studied using X-ray diffraction (XRD). In order to study morphology of powders, scanning electron microscopy (SEM) was performed. The crystalline PZT and Nb-doped PZT powders were pelleted into discs and sintered at 1100, 1150 and 1200°C, with a heating rate of 10°C/min, and holding time of 1-6 h to find the optimum combination of temperature and time to produce high density ceramics. Microstructural characterization was conducted on the fractured ceramic surfaces using SEM. Density measurements showed that maximal density of 95% of the theoretical density was achieved after sintering of PZT and PZTN ceramics at 1200°C for 2 h and 4 h, respectively. However, the results of dielectric measurements showed that PZTN ceramics have higher relative permittivity (ε r ∼17960) with lower Curie temperature (∼358°C) relative to PZT (ε r = 16000 at ∼363°C) as a result of fine PZTN structure as well as presence of vacancies. In addition, dielectric loss (at 1 kHz) of PZT and PZTN ceramics with 95% theoretical density was 0.0087 and 0.02, respectively. The higher dielectric loss in PZTN was due to easier domain wall motions in PZTN ceramics.

Chemosensors

Ternary systems are less studied for sensing applications due to complex synthesis procedures. Ho... more Ternary systems are less studied for sensing applications due to complex synthesis procedures. However, they have more sources of resistance modulation, leading to an enhanced gas response. In this study, a ternary system, namely Au-decorated ZnO-polyaniline (PANI) composite nanofibers with different amounts of PANI (10, 25, and 50 wt.%) were synthesized for NO2 gas sensing studies. First, ZnO nanofibers were synthesized by electrospinning, and then an Au layer (9 nm) was coated on the ZnO nanofibers. Finally, PANI was coated onto the prepared Au-decorated ZnO nanofibers. NO2 gas sensing investigations indicated that the sensor with 25 wt.% PANI had the best response to NO2 gas at 300 °C. In addition, the optimized sensor exhibited high selectivity to NO2 gas. The improved performance of the optimal gas sensor was attributed to the role of Au, the formation of ZnO-PANI heterojunctions, and the optimal amount of PANI. The promising effect of this ternary system for NO2 sensing was de...

Sensors and Actuators B: Chemical

Lecture Notes in Electrical Engineering, 2017

In this paper is reported the development of microstrip resonators working in the frequency range... more In this paper is reported the development of microstrip resonators working in the frequency range of 3–6 GHz and their employment in the investigation of the sensing properties of nanostructured materials towards gas. The materials are deposited as films on the gap of the resonators by drop coating aqueous solutions of Ag@α-Fe2O3 nanocomposite having a core–shell structure. Here are reported sensing data about humidity monitoring in the range from 0 to 70%. The increase of humidity value brings to a large frequency shift of the resonance one. The good characteristics of the fabricated device suggest its promising use as humidity sensor.

In this paper, stable water solution using a Pechini sol-gel process was prepared. The solution w... more In this paper, stable water solution using a Pechini sol-gel process was prepared. The solution was used for the direct printing of iron oxide precursor on alumina substrates. To convert the precursor to the desired iron oxide phase, an annealing step was carried out at elevated temperatures (>450 °C). In this work a α-Fe2O3 thin film-based chemoresistive sensors for ethanol detection in air were fabricated. The device developed was investigated for evaluate the sensing characteristics such sensitivity, selectivity and stability.

TrAC Trends in Analytical Chemistry, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Asian Journal of Atmospheric Environment, 2020

Resistive-based gas sensors built through the combination of semiconducting metal oxides and cond... more Resistive-based gas sensors built through the combination of semiconducting metal oxides and conducting polymers (CPs) are widely used for the detection of diverse gaseous components. In light of the great potential of each of these components, electrospun CPs produced by a facile electrospinning method can offer unique opportunities for the fabrication of sensitive gas sensors for diverse gaseous compounds due to their large surface area and favorable nanomorphologies. This review focuses on the progress achieved in gas sensing technology based on electrospun CPs. We offer numerous examples of CPs as gas sensors and discuss the parameters affecting their sensitivity, selectivity, and sensing mechanism. This review paper is expected to offer useful insights into potential applications of CPs as gas sensing systems.

International Journal of Hydrogen Energy, 2019

Hydrogen has captured a lot of attention in recent years because its abundance, cleanness and one... more Hydrogen has captured a lot of attention in recent years because its abundance, cleanness and one of the most promising sources of green energy. However, hydrogen has an explosive nature. Accordingly, detection of hydrogen leaks is important from a safety point of view. In this review paper, we use numerous examples to explain how Pd-decoration on the surfaces of nanomaterials can lead to enhancements in response and selectivity toward hydrogen gas. First, we describe the importance of hydrogen detection, then the properties of Pd and PdH x are reviewed, and metallic Pd hydrogen gas sensors are discussed. Finally, we comprehensively review different semiconducting gas sensors decorated with Pd with more emphasis on the sensing mechanism. This review paper provides a simple yet informative background for researchers working in this hot field.

Optik, 2018

ZnO/reduced graphene oxide (RGO) heterostructures were fabricated using a simple two-step wet che... more ZnO/reduced graphene oxide (RGO) heterostructures were fabricated using a simple two-step wet chemical technique and post-annealing treatment. ZnO nanoparticles with different sizes (20-200 nm) and shapes were randomly distributed on mono-and/or multilayered RGO sheets. The microstructures of the ZnO/RGO composites examined using transmission electron microscopy indicated that the heterostructures are polycrystalline in nature, implying the possibilities of diverse defects present in the samples. The photoluminescence spectra examinations revealed the enhancement of defect-level emission peaks observed at a relatively long wavelength ranges (i.e., 779 nm, 666 nm, and 574 nm) as compared with the band to band transition observed at relatively short wavelengths (i.e., 378 nm).

Current Applied Physics, 2018

MoO 3 eZnO coreeshell nanorods were synthesized by a simple two-step process. MoO 3 nanorods were... more MoO 3 eZnO coreeshell nanorods were synthesized by a simple two-step process. MoO 3 nanorods were synthesized by a hydrothermal method, which was followed by atomic layer deposition of a ZnO shell. The phase and crystallinity of the synthesized products were examined by X-ray diffraction, and the morphological features were studied by scanning electron microscopy. Gas sensing tests were performed on both pristine MoO 3 nanorods and MoO 3 eZnO coreeshell nanorods. Sensors containing the pristine MoO 3 nanorods and MoO 3 eZnO coreeshell nanorods showed responses (R a /R g where R a and R g are the electrical resistances of the sensors in air and the target gas, respectively) of 1.15 and 7.6, respectively, to 200 ppm ethanol at 350 C. Therefore, the response of the MoO 3 eZnO coreeshell nanorod sensors to ethanol gas was significantly better than that of pristine MoO 3 nanorods. The underlying mechanisms for the enhanced sensing performance are discussed in detail.

Applied Surface Science, 2017

Highlights  Pristine WO3 nanorods and Cr2O3-functionalized WO3 nanorods were synthesized.  The ... more Highlights  Pristine WO3 nanorods and Cr2O3-functionalized WO3 nanorods were synthesized.  The Cr2O3-functionalized WO3 nanorod sensor showed a stronger response to these gases than the pristine WO3 nanorod sensor.  The former sensor showed a shorter response and recovery time than the latter one.  The Cr2O3-functionalized WO3 nanorods sensor showed good selectivity toward ethanol.  The underlying mechanisms for the enhanced sensing performance of the functionalized sensor are discussed in detail.

Chemosensors, 2016

The development of an electrochemical dissolved oxygen (DO) sensor based on a novel Cu(II) comple... more The development of an electrochemical dissolved oxygen (DO) sensor based on a novel Cu(II) complex-modified screen printed carbon electrode is reported. The voltammetric behavior of the modified electrode was investigated at different scan rates and oxygen concentrations in PBS (pH = 7). An increase of cathodic current (at about´0.4 vs. Ag/AgCl) with the addition of oxygen was observed. The modified Cu(II) complex electrode was demonstrated for the determination of DO in water using chronoamperometry. A small size and low power consumption home-made portable electrochemical analyzer based on custom electronics for sensor interfacing and operating in voltammetry and amperometry modes has been also designed and fabricated. Its performances in the monitoring of DO in water were compared with a commercial one.

Measurement, 2016

Abstract AgNPs/PMA hybrid nanocomposite materials with different Ag loadings have been synthesize... more Abstract AgNPs/PMA hybrid nanocomposite materials with different Ag loadings have been synthesized using a simple chemical route assisted by UV irradiation. The hybrid composites were characterized by means of SEM and TEM, UV–vis spectroscopy and XPS. The as synthesized hybrid samples, composed of small Ag nanoparticles (AgNPs) embedded within the PMA (poly-methacrylic-acid) matrix, have been used to modify the working electrode of disposable screen printed carbon electrodes (SPCEs). It has been observed that hybrid composite with the lowest Ag loading forms dendritic silver structures on the surface of working electrode, whereas at higher loadings massive structures were formed. The electrocatalytic properties of the AgNPs/PMA/SPCEs were investigated toward the reduction of nitrate at neutral pH. Based on these modified electrodes, both voltammetric and amperometric sensors were developed for the electrochemical sensing of nitrate. Voltammetric sensor showed a wide linear range (0–20 mM) and high sensitivity (130 μA mM −1 cm −2 ).

Ceramics International, 2016

Abstract In the present work, α-Fe2O3 nanoparticles were successfully synthesized by Pechini sol–... more Abstract In the present work, α-Fe2O3 nanoparticles were successfully synthesized by Pechini sol–gel (PSG) method following annealing at 550 °C. The morphology and microstructure of the prepared α-Fe2O3 nanoparticles were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman analysis. The electrical and sensing properties were also investigated. The α-Fe2O3 based sensor showed good sensitivity and selectivity towards ethanol at the optimal temperature of 225 °C. Moreover, the sensor displayed good electrical and sensing stability. These results suggest the potential applications of α-Fe2O3 synthesized by Pechini sol–gel method as a sensor material for ethanol detection.

Journal of Nanoscience and Nanotechnology, 2017

Journal of Nanostructure in Chemistry, 2016

In this study, the size-controlled synthesis of silver nanoparticles (Ag NPs) via chemical reduct... more In this study, the size-controlled synthesis of silver nanoparticles (Ag NPs) via chemical reduction method by NaBH 4 as a reducing agent and poly(vinyl pyrrolidone) or PVP as a stabilizing agent is reported. Changing of ratios between reducing agent and stabilizing agent relative to AgNO 3-optimized conditions for synthesis of stable Ag NPs was studied. The formation of Ag NPs was tracked by UV-Vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. Particle size distribution was studied by particle size analyzer, and the morphology was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical properties of the synthesized Ag NPs were also investigated. The optimized Ag NPs were very stable even after 1 month that was due to effective stabilization by PVP molecules. The mechanism of Ag NPs formation and stabilization is discussed in detail.

Ceramics International, 2016

Abstract In this communication, Ag/Fe 2 O 3 nanocomposites were successfully synthesized by reduc... more Abstract In this communication, Ag/Fe 2 O 3 nanocomposites were successfully synthesized by reduction of silver nitrate with NaBH 4 and subsequent coating of Fe 2 O 3 by a simple Pechini sol-gel method. Synthesized powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Gas sensing properties of Ag/Fe 2 O 3 nanocomposites and pristine Fe 2 O 3 were studied at different temperature and in the presence of different gases. It was found that Ag/Fe 2 O 3 sensor even can detect 500 ppb NO 2 gas at 150 °C, whereas pristine Fe 2 O 3 sensor showed no significant response to NO 2 . The possible mechanisms of NO 2 sensing by Ag/Fe 2 O 3 are discussed in detail.

IOP Conference Series: Materials Science and Engineering, 2015