scholarly journals Precise Control of Surface Oxygen Vacancies in ZnO Nanoparticles for Extremely High Acetone Sensing Response

2021 ◽  
Author(s):  
Jihyun Lee ◽  
Youngmoon Choi ◽  
Byoung Joon Park ◽  
Jeong Woo Han ◽  
Hyun-Sook Lee ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Oxygen Vacancies ◽  
Surface Defects ◽  
High Sensitivity ◽  
Fast Response ◽  
Oxide Semiconductor ◽  
Surface Oxygen ◽  
Zno Nps ◽  
Precise Control ◽  
Optimal Surface

Abstract ZnO has been studied intensely for chemical sensors due to its high sensitivity and fast response. Here, we present a simple approach to precisely control oxygen vacancy contents to provide significantly enhanced acetone sensing performance of commercial ZnO nanopowders. A combination of H2O2 treatment and thermal annealing produces optimal surface defects with oxygen vacancies on the ZnO nanoparticles (NPs). The highest response of ~27,562 was achieved for 10 ppm acetone in 0.125 M H2O2 treated/annealed ZnO NPs at the optimal working temperature of 400 ℃, which is significantly higher than that of reported so far in various acetone sensors based on metal-oxide-semiconductor (MOS). Furthermore, first-principles calculations indicate that pre-adsorbed O formed on the surface of H2O2-treated ZnO NPs can provide a favorable adsorption energy, especially for acetone detection, due to strong bidentate bonding between carbonyl C atom of acetone molecules and pre-adsorbed O on the ZnO surface. Our study demonstrates that controlling surface oxygen vacancies by H2O2 treatment and re-annealing at optimal temperature is an effective method to improve the sensing properties of commercial MOS materials.

scholarly journals Nanoscaled Electrocatalytic Optically Modulated ZnO Nanoparticles through Green Process ofPunica granatumL. and Their Antibacterial Activities

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Xolile Fuku ◽  
Abdoulaye Diallo ◽  
Malik Maaza
Keyword(s):  
Metal Oxide ◽  
Green Synthesis ◽  
Zno Nanoparticles ◽  
Metal Oxide Nanoparticles ◽  
Antibacterial Activities ◽  
Oxide Semiconductor ◽  
Bacterial Strains ◽  
Zno Nps ◽  
Nanoparticle Biosynthesis ◽  
High Concentrations

Most recently, green synthesis of metal oxide nanoparticles has become an interesting subject of the nanoscience and nanotechnology. The use of plant systems has been deemed a green route and a dependable method for nanoparticle biosynthesis, owing to its environmental friendly nature. The present work demonstrates the bioreductive green synthesis of nanosized zinc oxide (ZnO) using peel extracts of pomegranate. Highly crystalline ZnO nanoparticles (ZnO NPs) which are 5 nm in particle size were characterised by HRTEM and XRD. FT-IR spectra confirmed the presence of the biomolecules and formation of plant protein-coated ZnO NPs and also the pure ZnO NPs. Electrochemical investigation revealed the redox properties and the conductivity of the as-prepared ZnO nanoparticles. The optical band gap of ZnO NPs was calculated to be 3.48 eV which indicates that ZnO NPs can be used in metal oxide semiconductor-based devices. Further, the nanomaterials were also found to be good inhibitors of bacterial strains at both low and high concentrations of 5–10 mg mL−1.

Relationships of surface oxygen vacancies with photoluminescence and photocatalytic performance of ZnO nanoparticles

2005 ◽  
Vol 48 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Liqiang Jing ◽  
Fulong Yuan ◽  
Haige Hou ◽  
Baifu Xin ◽  
Weimin Cai ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Oxygen Vacancies ◽  
Photocatalytic Performance ◽  
Surface Oxygen

scholarly journals A Carbon Nanotube–Metal Oxide Hybrid Material for Visible-Blind Flexible UV-Sensor

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 368
Author(s):  
Pawan Pathak ◽  
Sanghoon Park ◽  
Hyoung Jin Cho
Keyword(s):  
Carbon Nanotube ◽  
Metal Oxide ◽  
Mechanical Stability ◽  
High Sensitivity ◽  
Fast Response ◽  
Oxide Semiconductor ◽  
Smart Devices ◽  
Wearable Electronics ◽  
Sensing Applications ◽  
Multi Walled Carbon Nanotubes

Flexible sensors with low fabrication cost, high sensitivity, and good stability are essential for the development of smart devices for wearable electronics, soft robotics, and electronic skins. Herein, we report a nanocomposite material based on carbon nanotube and metal oxide semiconductor for ultraviolet (UV) sensing applications, and its sensing behavior. The sensors were prepared by a screen-printing process under a low-temperature curing condition. The formation of a conducting string node and a sensing node could enhance a UV sensing response, which could be attributed to the uniform mixing of functionalized multi-walled carbon nanotubes and zinc oxide nanoparticles. A fabricated device has shown a fast response time of 1.2 s and a high recovery time of 0.8 s with good mechanical stability.

Enhanced Effect of Band Bending on Visible Photoluminescence from ZnO Nanoparticles of Smaller Sizes in Ionic Environment

2019 ◽  
Vol 11 (12) ◽  
pp. 1231-1237
Author(s):  
Subhamay Pramanik ◽  
Sumit Mukherjee ◽  
Manoranjan Ghosh ◽  
Sandip Das ◽  
Subal C. De ◽  
...  
Keyword(s):  
Surface Charge ◽  
Zno Nanoparticles ◽  
Oxygen Vacancies ◽  
Relative Number ◽  
Depletion Layer ◽  
Visible Emission ◽  
Zno Nps ◽  
Band Bending ◽  
Visible Photoluminescence ◽  
Ionic Environment

We report a novel approach to control the defect-mediated visible photoluminescence (PL) of small ZnO nanoparticles (NPs) by changing the ionic environment viz. concentration of LiClO4 or NaCl (electrolytes) in the medium in which NPs are dispersed. For both the electrolytes, overall intensity of visible PL emission decreases and the spectral components (∼2.35 eV and ∼2.19 eV) of it shift towards lower energy side with increase in electrolyte concentration. Such changes are more prominent in case of NaCl than LiClO4. We have explained all these observations in the basis of accumulation of surface charge, due to the presence of electrolyte, which controls the band bending in the depletion layer at the surface of the NPs. Furthermore, the band bending results in corresponding change of number of emission centres (here, relative number of singly ionized oxygen vacancies or doubly ionized oxygen vacancies) which predominantly decides the nature of visible emission. An enhancement of this effect has been observed in case of smaller NPs of size comparable to the width of the depletion layer. This study can open up a way to control the visible emission from the ZnO NPs and can be useful for sensing the processes involving surface charge in the fields such as biophysics and biochemistry.

scholarly journals Tin Disulfide-Coated Microfiber for Humidity Sensing with Fast Response and High Sensitivity

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 648
Author(s):  
Aijie Liang ◽  
Jingyuan Ming ◽  
Wenguo Zhu ◽  
Heyuan Guan ◽  
Xinyang Han ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Small Diameter ◽  
High Sensitivity ◽  
Large Change ◽  
Small Variation ◽  
Response Speed ◽  
Fast Response ◽  
Tin Disulfide ◽  
Recovery Times ◽  
Response And Recovery

Breath monitoring is significant in assessing human body conditions, such as cardiac and pulmonary symptoms. Optical fiber-based sensors have attracted much attention since they are immune to electromagnetic radiation, thus are safe for patients. Here, a microfiber (MF) humidity sensor is fabricated by coating tin disulfide (SnS2) nanosheets onto the surface of MF. The small diameter (~8 μm) and the long length (~5 mm) of the MF promise strong interaction between guiding light and SnS2. Thus, a small variation in the relative humidity (RH) will lead to a large change in optical transmitted power. A high RH sensitivity of 0.57 dB/%RH is therefore achieved. The response and recovery times are estimated to be 0.08 and 0.28 s, respectively. The high sensitivity and fast response speed enable our SnS2-MF sensor to monitor human breath in real time.

scholarly journals Antibacterial and Photocatalytic Properties of ZnO Nanoparticles Obtained from Chemical versus Saponaria officinalis Extract-Mediated Synthesis

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2072
Author(s):  
Maria Antonia Tănase ◽  
Maria Marinescu ◽  
Petruta Oancea ◽  
Adina Răducan ◽  
Catalin Ionut Mihaescu ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Zno Nanoparticles ◽  
Model Compound ◽  
Size Composition ◽  
Inorganic Nanoparticles ◽  
Bacterial Strains ◽  
X Ray Diffraction ◽  
Zno Nps ◽  
Reaction Conditions ◽  
Saponaria Officinalis

In the present work, the properties of ZnO nanoparticles obtained using an eco-friendly synthesis (biomediated methods in microwave irradiation) were studied. Saponaria officinalis extracts were used as both reducing and capping agents in the green nanochemistry synthesis of ZnO. Inorganic zinc oxide nanopowders were successfully prepared by a modified hydrothermal method and plant extract-mediated method. The influence of microwave irradiation was studied in both cases. The size, composition, crystallinity and morphology of inorganic nanoparticles (NPs) were investigated using dynamic light scattering (DLS), powder X-ray diffraction (XRD), SEM-EDX microscopy. Tunings of the nanochemistry reaction conditions (Zn precursor, structuring agent), ZnO NPs with various shapes were obtained, from quasi-spherical to flower-like. The optical properties and photocatalytic activity (degradation of methylene blue as model compound) were also investigated. ZnO nanopowders’ antibacterial activity was tested against Gram-positive and Gram-negative bacterial strains to evidence the influence of the vegetal extract-mediated synthesis on the biological activity.

scholarly journals A Full-Range Flexible and Printed Humidity Sensor Based on a Solution-Processed P(VDF-TrFE)/Graphene-Flower Composite

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1915
Author(s):  
Shenawar Ali Khan ◽  
Muhammad Saqib ◽  
Muhammad Muqeet Rehman ◽  
Hafiz Mohammad Mutee Ur Rehman ◽  
Sheik Abdur Rahman ◽  
...  
Keyword(s):  
Active Layer ◽  
Humidity Sensor ◽  
High Reliability ◽  
Full Range ◽  
High Sensitivity ◽  
Fast Response ◽  
Considerable Change ◽  
Relative Humidity Range ◽  
Response And Recovery ◽  
Proportional Relationship

A novel composite based on a polymer (P(VDF-TrFE)) and a two-dimensional material (graphene flower) was proposed as the active layer of an interdigitated electrode (IDEs) based humidity sensor. Silver (Ag) IDEs were screen printed on a flexible polyethylene terephthalate (PET) substrate followed by spin coating the active layer of P(VDF-TrFE)/graphene flower on its surface. It was observed that this sensor responds to a wide relative humidity range (RH%) of 8–98% with a fast response and recovery time of 0.8 s and 2.5 s for the capacitance, respectively. The fabricated sensor displayed an inversely proportional response between capacitance and RH%, while a directly proportional relationship was observed between its impedance and RH%. P(VDF-TrFE)/graphene flower-based flexible humidity sensor exhibited high sensitivity with an average change of capacitance as 0.0558 pF/RH%. Stability of obtained results was monitored for two weeks without any considerable change in the original values, signifying its high reliability. Various chemical, morphological, and electrical characterizations were performed to comprehensively study the humidity-sensing behavior of this advanced composite. The fabricated sensor was successfully used for the applications of health monitoring and measuring the water content in the environment.

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