Thin Films, Materials Surface & Interfaces
Bruna Laís Pereira da Silva; Leonardo Barbosa da Silva; Letícia Dias dos Anjos Gonçalves; Rogério Valentim Gelamo; Vitor Tomaz Guimarães Naves; Lucas Donizete Silva; Emiliane Andrade Araújo Naves Naves
Abstract
The microbial adhesion of pathogens on surfaces, followed by the formation of biofilms, constitute one important causes of diseases transmitted by foods. Biofilm control in the food industry is critical since biofilm removal is challenging. Thus, the functionalization of surfaces has been a strategy ...
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The microbial adhesion of pathogens on surfaces, followed by the formation of biofilms, constitute one important causes of diseases transmitted by foods. Biofilm control in the food industry is critical since biofilm removal is challenging. Thus, the functionalization of surfaces has been a strategy to prevent the multiplication of bacteria. This study aimed to functionalize stainless steel surfaces with zinc and niobium oxides and to analyze its antimicrobial capacity of Escherichia coli. In addition, the roughness surface was also investigated. The free energy of hydrophobic interaction was calculated by measuring the contact angle. The results showed that surface functionalization with metallic oxides efficiently controlled E. coli adhesion, achieving more than two decimal reductions in the initial population. It was found that the deposition of oxides modified the hydrophobicity of the stainless steel surface, making it hydrophilic, which may have added to the effect of functionalization for the antimicrobial efficiency of the obtained surface. The surfaces functionalized with zinc and niobium oxides had the highest roughness. Thus, surfaces with Nb and Zn oxides can be a promising alternative for application in the food industry to help control adhesion and obtain the final product of microbiological quality.
Arnab Sankar Bhattacharyya; Ritambhara Dash
Abstract
The rGO-ZnO composite was found promising improvement over the photocatalytic ability of pure ZnO and is useful for other Opto-chemical applications. ZnO/rGO composite was synthesized by the sol-gel method. The morphology of rGO caused better dispersion of the ZnO crystallites The reducing agent ammonia ...
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The rGO-ZnO composite was found promising improvement over the photocatalytic ability of pure ZnO and is useful for other Opto-chemical applications. ZnO/rGO composite was synthesized by the sol-gel method. The morphology of rGO caused better dispersion of the ZnO crystallites The reducing agent ammonia was varied in concentration during the synthesis. A reduction in the crystallization was observed for lower concentrations (0 – 1%) of ammonia which got stabilized in higher concentrations (>1%). The crystalline morphology showed variations from being close to amorphous to 38 nm. The average crystallite size was 15 nm. The rGO induced nonradiative phononic modes in the optical transition process when present in lower concentration but interestingly aided the crystallization process in a preferential crystallographic orientation which however got lowered in intensity for >2% ammonia concentration. The defect states formed in the rGO/ZnO composite in the form of oxygen vacancies, zinc interstitials, and vacancies caused a decrease in band gap due to indirect transitions. The role of ammonia in the performance of the composites was found to be significant
G.A. Suganya Josephine; K. Jayaprakash; A. Sivasamy
Abstract
Heterogeneous semiconductor nanomaterials are widely employed nowadays as efficient photocatalysts for selective organic transformation reactions. A co-precipitation technique was employed for the preparation of ZnO doped dysprosium oxide from the respectivemetal nitrates and characterization studies ...
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Heterogeneous semiconductor nanomaterials are widely employed nowadays as efficient photocatalysts for selective organic transformation reactions. A co-precipitation technique was employed for the preparation of ZnO doped dysprosium oxide from the respectivemetal nitrates and characterization studies were conductedby FT-IR, X-Ray Differaction, UV-Visible-DRS and FE-SEM analysis. XRD showed the prepared nanomaterial to be in a nano range with high crystallinity. The particles possesed a spherical morphology and of the order of 40-50 nm(particle size) as evidenced from FE-SEM analysis. From theUV-Visible-DRS analysis the band gap energy was calculated as 3.15 eV. The synthesizedZnO doped dysprosium oxide was employed as a photocatalyst under UV light irradiation for selective organic transformation reaction. Quinones especially benzoquinones are a class of compounds which forms a basic structural skeleton for various natural compounds. They are widely employed asa precursor for natural products synthesis. Herein we report the synthesis of N-phenyl-p-benzoquinonimine from diphenylamine by employing ZnO doped dysprosium oxide as a photocatalyst under UV light irradiation in ethanol. Thin Layer Chromatography was used to check the progress of the reaction. Optimization studies for the reaction parameters were conducted systematically.
R Subba Reddy; S Uthanna; A Sivasankar Reddy; T. Srikanth; B. Radha Krishna
Abstract
Zinc oxide thin films were deposited by RF magnetron sputtering on p-type (100) silicon and glass substrates held at room temperature by varying the oxygen partial pressures and the optimized films was annealing at different temperatures. The deposition rate of the films was decreased from 5.8 to 2.5 ...
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Zinc oxide thin films were deposited by RF magnetron sputtering on p-type (100) silicon and glass substrates held at room temperature by varying the oxygen partial pressures and the optimized films was annealing at different temperatures. The deposition rate of the films was decreased from 5.8 to 2.5 nm /min with increase of oxygen partial pressures. X- ray diffraction results reveal that the films deposited at oxygen partial pressure of 2x10-2 Pa the (100) preferred orientation peak crystallinity became better. Raman spectroscopy analysis shows an improvement in the crystalline quality of the films at 2x10-2 Pa. Fourier transform infrared spectroscopy of ZnO films confirms the presence Zn-O bonding. The nanorods were observed at oxygen partial pressure of 5x10-2 Pa. The maximum transmittance of 97% and crystallite size of 21 nm was observed at oxygen partial pressure of 2x10-2 Pa. The as deposited films annealed at 473 K the intensity of (100) phase was decreased. The RMS roughness of the as deposited ZnO films was 7.3 nm, and it increased to 30 nm for the films annealed at 473K. Optical spectra revealed the films annealed at 673 K show the optical band gap of 3.17 eV. Copyright © 2018 VBRI Press.
Pawan Kumar; Amit Sanger; Arvind Kumar; Davinder Kaur; Ramesh Chandra
Abstract
In the present work, gas sensing properties of Copper (Cu) doped Zinc Oxide (ZnO) thin films have been investigated. The nanostructured ZnO and Cu doped ZnO (CZO) thin films have been synthesized using DC magnetron sputtering on glass substrates. The effect of hydrophobicity and surface roughness of ...
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In the present work, gas sensing properties of Copper (Cu) doped Zinc Oxide (ZnO) thin films have been investigated. The nanostructured ZnO and Cu doped ZnO (CZO) thin films have been synthesized using DC magnetron sputtering on glass substrates. The effect of hydrophobicity and surface roughness of the CZO thin films on the carbon monoxide (CO) gas sensing performance have been examined. Fast response time (47 sec) and an optimum recovery time (~ 86 sec) have been witnessed at an adequate temperature of 250°C for the samples having contact angle ~ 131o and surface roughness ~ 14.86 nm. Hydrophobicity of the surface provides short recovery time by opposing the existence of water-vapour on the surface. Copyright © 2018 VBRI Press.
Malatesh S. Pujar; Shirajahammad M. Hunagund; Vani R. Desai; Ashok H. Sidarai
Abstract
Herein, we synthesis ZnO nanosheets via facial hydrothermal method using sodium hydroxide (NaOH) as a stabilizer. The synthesized ZnO was subjected to various characterizations for analysis of their optical, structural, functional groups, chemical composition, surface morphological and thermal studies, ...
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Herein, we synthesis ZnO nanosheets via facial hydrothermal method using sodium hydroxide (NaOH) as a stabilizer. The synthesized ZnO was subjected to various characterizations for analysis of their optical, structural, functional groups, chemical composition, surface morphological and thermal studies, obtained results reveals the following features; UV-Vis spectroscopy analysis shows absorption maximum at 272 nm which confirms the preliminary presence of ZnO material. X-ray diffraction (XRD) analysis reveals the average crystalline grain size is found to be of around 38.10 nm. Fourier transform infrared spectroscopy (FT-IR) analysis reveals the presence of O-H, C-H, C-N and Zn-O bands. Atomic force microscopy (AFM) and scanning electron microscopy analysis (SEM) shows the topological structure of ZnO and it having nanosheets like nature. Energy dispersive X-ray spectroscopy (EDS) analysis confirms the chemical compositions were Zn and O elements. Further, we observed by thermo gravimetric analysis (TGA) that for synthesized ZnO nanosheets weight loss is of 15.574% was occurred at 47.49˚ C to 300˚ C. After 300˚C, none of the materials underwent greater than 1% of weight loss. From DSC analysis, we observed that there are endothermic reactions in between 23˚C to 500˚C. In addition, we proposed to study biological activities of these synthesized ZnO nanosheets. Copyright © 2018 VBRI Press
Sitakshi Gupta; Chhaya Ravikant
Abstract
Nowadays, gas sensors are fast becoming an imperative part of modern life with extensive applications in domestic safety, environmental monitoring, industrial process control, public security, medical applications and chemical warfare assessment amongst many others. The detection of minor gas leaks has ...
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Nowadays, gas sensors are fast becoming an imperative part of modern life with extensive applications in domestic safety, environmental monitoring, industrial process control, public security, medical applications and chemical warfare assessment amongst many others. The detection of minor gas leaks has been a challenging area of research, particularly in view of the hazards to human health and safety posed by toxic gases like NO2, NO, CO, NH3 etc and combustible gases like methane, hydrogen gas and some volatile organic compounds. Thus it is imperative to evolve and employ simple yet reliable gas sensing mechanisms with optimum response and selectivity towards even low concentration of analyte gas at room temperature. Most of the conventional gas sensors are based on metal-oxide semiconductors which are low-cost, exhibit good sensitivity and fast response/recovery. Zinc oxide is one such n-type semiconducting oxide, which has been widely studied for gas sensing response due to its ease of fabrication, high sensitivity and environment-friendly nature. However, the operating temperature of such sensors is usually high (>200°C) owing to the wide band-gap (3.37 eV) and high electrical resistance (kΩ-MΩ), which limits their practical utilization. In order to be used in hazard monitoring and home/workplace safety, the gas sensors need to be sensitive to gas exposure in mild operating conditions. As an alternative, more recently, graphene and its derivatives like pristine graphene (PG), reduced graphene oxide (rGO) etc. have been studied for sensing applications owing to their exceptional electronic and physical properties such as high carrier mobility at room temperature, good thermal stability, high mechanical strength, ballistic conductivity and large specific surface area. These sensors show high sensitivity at low operating temperatures (down to room temperature) towards low concentrations of analyte gas. However most of these rGO based sensors exhibit relatively longer response/recovery times than metal-oxide based gas sensors. Hence, nanocomposites formed by hybridizing graphene or its derivatives with metal-oxide nanoparticles are being explored as gas sensing materials. Combining reduced graphene oxide with zinc oxide to form hybrid nanostructures is particularly interesting because not only do they display the individual properties of the metal oxide NPs (faster response/recovery times) and of graphene (high electronic conductivity leading to efficient room temperature gas response), but may also have synergistic effects leading to better sensitivity as a gas sensing material. Here we present a review of the recent progress in rGO-ZnO nanocomposites based gas sensors. Copyright © 2018 VBRI Press.
Nandini Sharma; Ranjana Jha
Abstract
Zinc oxide nanoparticles were synthesized utilizing a green and simple sonochemical route. The synthesized ZnO nanoparticles were characterized for the analysis of structural and optical properties. Characterization with XRD and TEM shows that the synthesized particles were uniformly distributed, crystalline ...
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Zinc oxide nanoparticles were synthesized utilizing a green and simple sonochemical route. The synthesized ZnO nanoparticles were characterized for the analysis of structural and optical properties. Characterization with XRD and TEM shows that the synthesized particles were uniformly distributed, crystalline in nature with spherical shape and narrow size distribution of particles (48-50 nm). UV-Vis and PL spectra shows optical band gap to be 3.5 eV and ZnO sample possess fewer defect states. ZnO nanoparticles synthesized shows good optical properties and was observed to be a promising candidate to be used in thin film solar cells. Copyright © 2017 VBRI Press.
M. Kanakadurga; S. R. Murthy; Arya Das; Rakesh K. Sahoo; Saroj K. Singh
Abstract
ZnO nano-platelets have been prepared using a high pressure reactor via hydrothermal route. The as-formed fine platelets morphology of the as-synthesized powder was confirmed from the scanning electron microscopy (SEM) images. The elemental analysis using energy dispersive X-ray (EDAX) analysis indicated ...
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ZnO nano-platelets have been prepared using a high pressure reactor via hydrothermal route. The as-formed fine platelets morphology of the as-synthesized powder was confirmed from the scanning electron microscopy (SEM) images. The elemental analysis using energy dispersive X-ray (EDAX) analysis indicated the presence of Zn, O, Na and Cl which confirms the presence of ZnO as major and NaCl as the minor phase. The precipitation of this minor phase after growth and catalytic induction in nano-platelet (NP) morphology during growth has been elucidated. The electrochemical performance of this as-synthesized powder is quite promising. Additionally, the effect of this minor NaCl phase in changing the ionic equilibrium of the electrolyte in capacitance measurement has been analyzed.
