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1.
Chemistry ; 29(27): e202300137, 2023 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-36807426

RESUMO

The electrochemical oxygen evolution reaction (OER) is a key process in many renewable energy systems. The development of low-cost, long-lasting alternatives to precious-metal catalysts, particularly functional electrocatalysts with high activity for OER processes, is crucial for reducing the operating expense and complexity of renewable energy generating systems. This work describes a concise method for generating marigold flower-like metal-organic frameworks (MOFs) aided manganese vanadium oxide via a hydrothermal procedure for increased OER activity. As synthesized MOF MnV oxide has a higher surface area due to the 3D flower-like structure, which is reinvented with enhanced electrocatalytic active sites. These distinctive structural features result in remarkable catalytic activity for MOF MnV oxide microflowers towards OER with a low overpotential of 310 mV at 50 mA cm-2 and a Tafel slope with only 51.4 mV dec-1 in alkaline conditions. This study provides a concise method for developing an optimized catalytic material with greater morphology and beneficial features for potential energy and environmental applications.

2.
Luminescence ; 37(2): 323-331, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34871472

RESUMO

There have been strong demands for nanofibrous scaffolds fabricated by electrospinning for various fields due to their various advantages. Electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fibre mats were prepared. The effects of processing variables as well as the inclusion of poly(ethylene glycol) (PEG) on the morphologies of generated fibres were investigated using Fourier-transform infrared spectroscopy and scanning electron microscopy. The average fibrous diameter was monitored in the range 400-3000 nm relying on the total content of PEG. The fluorescence cell imaging of electrospun mats was also explored. The results of cell viability demonstrated that skin fibroblast BJ-1 cells showed different adhesions and growth rates for the three kinds of PHBV fibres. Electrospun PHBV mats with low amount of PEG offer a high-quality medium for cell growth. Therefore, those mats exhibited high potential for soft tissue engineering, in particular wound healing.


Assuntos
Nanofibras , Engenharia Tecidual , Ácido 3-Hidroxibutírico , Proliferação de Células , Hidroxibutiratos , Poliésteres , Polietilenoglicóis
3.
Luminescence ; 37(1): 40-50, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34551199

RESUMO

Photochromism has been applied as an interesting technique in order to improve the anticounterfeiting of commercial commodities. To build up a mechanically reliable anticounterfeiting nanocomposite, it has been vital to enhance the engineering process of the anticounterfeiting material. In the current study, we developed mechanically reliable and highly photoluminescent lanthanide-doped strontium aluminate nanoparticles (LSAN)/polyacrylonitrile (PAN) hybrid nanofibres successfully fabricated using an electrospinning technique for anticounterfeiting applications. The produced nanocomposite films exhibited ultraviolet-induced photochromic anticounterfeiting properties. To guarantee the transparency of the LSAN-PAN film, LSAN must be immobilized onto the nanoparticle size to allow better dispersion without aggregation in the polyacrylonitrile matrix. The LSAN-PAN nanofibrous film demonstrated absorbance intensity that exhibited at 354 nm and associated with an emission intensity at 424 nm. The produced LSAN-PAN films demonstrated an enhanced hydrophobicity when increasing the ratio of LSAN, without adversely influencing their native appearance and mechanical performance. Upon excitation with ultraviolet light, the translucent nanofibrous substrates exhibited fast and reversible photochromic activity to greenish-yellow without exhaustion. The nanofibrous films exhibited stretchability, transparency, flexibility, and ultraviolet light-induced photochromism at low cost. The current strategy can be considered as an efficient technique towards the development of various anticounterfeiting materials for a better market with economic and social values.


Assuntos
Elementos da Série dos Lantanídeos , Nanofibras , Nanopartículas , Resinas Acrílicas , Luminescência , Estrôncio
4.
Luminescence ; 37(1): 97-107, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34713553

RESUMO

Photochromic and long-lasting photoluminescent transparent, rigid, ultraviolet (UV) protective and superhydrophobic poly(methyl methacrylate) (PMMA) plastic able to switch colour beneath UV irradiation was developed. Photoluminescent transparent PMMA plastic was prepared by the simple polymerization process of methyl methacrylate immobilized with alkaline earth aluminate (AEA) nanoparticles. These colourless PMMA plastic substrates showed a colour switch to greenish underneath UV light as proved using CIELAB screening. The morphology of AEA was evaluated using transmission electron microscopy. Conversely, transparent PMMA samples were evaluated using energy-dispersive X-ray spectra, scanning electron microscope, X-ray fluorescence spectroscopy and for hardness properties. Additionally, the photoluminescence properties were explored by studying excitation and emission spectra. The produced luminescence colourless PMMA plastic substrates displayed excitation band at 370 nm, and three emission peaks at 433, 494 and 513 nm. Photoluminescent PMMA with lower contents of AEA showed fast and reversible photochromism under UV light, while PMMA samples with higher contents of AEA showed long-lasting luminescence such as a flashlight with the ability to replace electric power. The findings showed that the produced photoluminescence colourless PMMA plastic substrates exhibited enhanced UV shielding and superhydrophobicity.


Assuntos
Nanopartículas , Polimetil Metacrilato , Luminescência , Polimerização
5.
Protein Expr Purif ; 169: 105548, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31786309

RESUMO

Japanese encephalitis virus (JEV) is a member of the Flavivirus genus and has recently attracted attention as a high-risk pathogen in the Asia-Pacific region, with up to 30% mortality in the afflicted patients. Recent outbreaks of flavivirus-associated infections around the world have put the focus on non-structural protein 1 (NS1) as a candidate for diagnostic and vaccine researches on flaviviruses. Although the JEV NS1 protein has been expressed in eukaryotic cells, attempts to express JEV NS1 in E. coli are on due to advantages such as rapid growth, easy manipulation, low cost, and high yield. However, the challenges of low yield and poor solubility of the proteins expressed in E. coli remain to be overcome. Herein, we reported successful expression of the JEV NS1 protein in E. coli Rosetta(DE3) strain. We standardized the temperature, induction time, as well as the concentration of the inducer for optimizing the expression of JEV NS1 in E. coli. Further, we successfully obtained soluble JEV NS1 from inclusion bodies by partial refolding during elution and gradual refolding during dialysis. Furthermore, the JEV NS1 protein was found to retain its molecular weight and was able to induce an immune response in the mouse. Western blot and indirect enzyme-linked immunosorbent assay were performed using the blood of the immunized mouse and purified JEV NS1 in this study. Hence, JEV NS1 expressed in and isolated from E. coli Rosetta(DE3) strain holds potential for application in vaccine development and diagnostic studies to combat Japanese encephalitis outbreaks in the future.


Assuntos
Vírus da Encefalite Japonesa (Espécie) , Proteínas não Estruturais Virais/biossíntese , Animais , Clonagem Molecular/métodos , Vírus da Encefalite Japonesa (Espécie)/imunologia , Vírus da Encefalite Japonesa (Espécie)/metabolismo , Escherichia coli/metabolismo , Camundongos , Proteínas Recombinantes/biossíntese , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/imunologia
6.
Analyst ; 145(9): 3222-3228, 2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-32118224

RESUMO

We report the analysis of deoxyribonuclease (DNase) activity by conjugation-free fluorescence polarisation in a droplet-based microfluidic chip. DNase is a DNA cleaving enzyme and its activity is important in the maintenance of normal cellular functions. Alterations in DNase activity have been implicated as the cause of various cancers and autoimmune diseases. To date, various methods for the analysis of DNase activity have been reported. However, they are not cost effective due to the requirement of large sample volumes and the need for the conjugation of fluorescent dyes. In this study, we have used ethidium bromide (EtBr), a DNA intercalating reagent, as a fluorescent reporter without any prior conjugation or modification of DNA. Degradation of DNA by DNase 1 was monitored at a steady state by making changes in the fluorescence polarisation of EtBr in droplets with a volume of 330 picolitre at a 40 hertz frequency under visible light. Using this technique, we successfully determined the half-maximal inhibitory concentration (IC50) of ethylenediaminetetraacetic acid (EDTA) for the inhibition of DNase 1 activity to be 1.56 ± 0.91 mM.


Assuntos
Desoxirribonucleases/metabolismo , Polarização de Fluorescência/métodos , Corantes Fluorescentes/química , DNA/química , DNA/metabolismo , Desoxirribonuclease I/metabolismo , Ácido Edético/química , Etídio/química , Dispositivos Lab-On-A-Chip
7.
Inorg Chem ; 59(6): 3817-3827, 2020 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-32090552

RESUMO

The development of bifunctional, highly active electrocatalysts for an overall water splitting reaction remains a major challenge. Here, the sacrificial template-assisted transformation of cobalt hydroxide nanowire (Co(OH)2 NW) into a metal-organic framework network (MOF) is conceived as a porous structure that provides extremely active and durable electrochemical energy conversion characteristics. After this, the 1D MOF modified Co NWs can be further transformed into a hybrid structure (MOF CoSeO3 NWs) by selenization. The self-template transformation strategy allows the interconnected porous conductive network to be exposed to abundant reactive sites and to improve electronic conductivity/structural integrity. Thus, the obtained catalyst established by electrocatalytic activity in the course of the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) in 1 M KOH solution requires overpotentials (η) of 290 and 150 mV to achieve a current density of 50 and 10 mA cm-2 for both OER and HER. Interestingly, as a full cell water electrolyzer (MOF CoSeO3 NWs (+) // MOF CoSeO3 NWs (-)), the MOF CoSeO3 NW's modified electrode exhibits an affordable cell voltage of 1.675 V at a current density of 100 mA cm-2. This work involves a viable and systematic strategy to prepare many other functional integrated MOFs that can be used for energy storage and conversion in multiple applications.

8.
Small ; 15(10): e1805242, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30690878

RESUMO

Precious metals such as palladium (Pd) and platinum (Pt) are marvelous materials in the fields of electronic and catalysis, but they are tapering day by day. Zr(IV)-based metal-organic frameworks (MOFs) are competent for their recovery, notably in harsh environments, while the general powder form limits their practical application. Porous MOF-based membranes with ultraefficient metal ion permeation, strong stability, and high selectivity are, therefore, strikingly preferred. Herein, a set of polymeric fibrous membranes incorporated with the UiO-66 series are fabricated; their adsorption/desorption capabilities toward Pd(II) and Pt(IV) are evaluated from strongly acidic solutions; and the MOF-polymer compatibilities are investigated. Polyurethane (PU)/UiO-66-NH2 showed strong acid resistance and high chemical stability, which are attributable to strong π-π interactions between PU and MOF nanoparticles with a high configuration of energy. The as-fabricated MOF membranes show extremely good adsorption/desorption performances without ruptures/coalitions of nanofibers or leak of MOF nanoparticles, and successfully display the efficacy in a gravity-driven or even continuous-flow system with good recycle performance and selectivity. The as-fabricated MOF membranes set an example of potential MOF-polymer compatibility for practical applications.

9.
J Nanosci Nanotechnol ; 19(6): 3558-3563, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30744785

RESUMO

In recent years, noise has become a serious hazard and can have permanent biological and psychological effects on humans and other organisms in nature. Textile materials are commonly used as absorbent acoustic materials for noise reduction. This work examines the use of electrospun nylon-6 and polyurethane nanofibres (PU NFs) to improve the sound absorption and sound insulation properties of polyurethane foam. In this work, nylon-6 and polyurethane nanofibres were prepared by an electrospinning technique and were glued to a polyurethane foam. The sound absorption coefficient of the materials was measured by the impedance tube method. An impedance tube was used to measure the sound absorption and airborne sound insulation. The results showed decreased sound absorption properties, whereas the sound insulation was highly enhanced when polyurethane/nanofibre hybrids were used, as compared to the pristine polyurethane foam. Furthermore, the sound insulation properties of polyurethane foam were highly enhanced when the foam was combined with nylon-6 NFs, compared with the polyurethane foam with PU NFs. Therefore, by investigating the acoustic characteristics of electrospun nylon-6 and PU nanofibres, we believe that this study can broaden the application of electrospun nanofibres for sound pollution control.


Assuntos
Caprolactama , Nanofibras , Caprolactama/análogos & derivados , Humanos , Polímeros , Poliuretanos
10.
J Environ Manage ; 206: 228-235, 2018 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-29073581

RESUMO

This study investigates three different strategies for anode surface treatment by doping superficial nitrogen groups on the anode surfaces of carbon cloth (CC) and carbon paper (CP). The chosen anodes were hydrothermally treated in the presence of an ammonia solution (AST), a mixture of nitric acid and sulfuric acid (AHT), and solid urea (UT) at 180 °C for 3 h. The utilized characterization techniques confirmed doping of nitrogen on the anode surfaces and a decrease in the oxygen-bonded carbon content. Furthermore, the results showed that the power and current densities were significantly affected by the surface modification techniques. Interestingly, the AST strategy achieved the highest power density of 159.3 mW-2 and 91.6 mWm-2, which revealed an increase in power of 115% and 56.8% for CC-AST and CP-AST, respectively. Additionally, the maximum coulombic efficiencies were 63.9% and 27.5% for the CC-AST and CP-AST anodes, respectively. Overall, these results highlight the significance of anode surface modification for enhancing MFC performance to generate electricity and treat actual wastewater.


Assuntos
Fontes de Energia Bioelétrica , Águas Residuárias , Carbono , Eletricidade , Eletrodos
11.
Analyst ; 142(7): 1149-1156, 2017 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-28317996

RESUMO

As one of the most promising fluorometric nanosensors for metal ion sensing, carbon nanodots (C-dots) have developed rapidly in recent years. However, it is still a thorny problem to shield the mutual interference of two metal ions towards C-dots, e.g., Hg2+ and Fe3+ ions. In the present work, we propose rational routes for the unique interaction between C-dots and Hg2+ or Fe3+. The selectivity of the as-obtained label-free C-dots can be effectively switched by P3O105- and SCN-. The resultant C-dots possess superior photoluminescence intensity stability in a wide pH range or in certain redox circumstances, which are highly preferred in terms of practical metal-ion detection. Moreover, the quenching-recovery-regeneration performances and quenching mechanisms were also investigated. Based on this stable and recoverable sensing platform, this in-depth study for dispelling interference from Hg2+ and Fe3+ ions may open up a new paradigm for developing potential detection of multi-metal ions using C-dots with switchable selectivity.

12.
Analyst ; 142(14): 2610-2616, 2017 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-28604851

RESUMO

We report the results of a label-free analysis of ribonuclease activity using droplet-based microfluidics. The ribonucleolytic activity of ribonucleases (RNases) plays a critical role in cellular functions such as development, survival, growth and differentiation. Altered ribonucleolytic activity and/or the expression level of the RNase A family are known to be associated with pancreatic, bladder, ovarian and thyroid cancers among others. For this reason, the RNase A family is a meaningful protein biomarker that can be used in the diagnosis of cancer and as a target for new drug screening. There are some successful traditional methods for analysing the RNase activity, such as radioactive label-based assay, methylene blue-based assay, gel zymography, as well as other more recently developed methods such as electrochemical assay and fluorescence resonance energy transfer (FRET). However, these methods require analytical samples with a volume ranging from microliters to milliliters, and are not suitable for high-throughput analysis. Therefore, we integrated ethidium bromide (EtBr), which intercalates the chemical itself to nucleic acid, to droplet-based microfluidics for a cost-effective, high-throughput analysis. Put simply, this method is dependent on the amount of intercalated EtBr molecules on RNA. Our assay also uses visible light that is harmless to humans, unlike previous methods that used harmful UV rays, to excite the EtBr molecules. Specifically, we monitored the ribonucleolytic activity of less than 10 nM RNase A in droplets of about 330 picoliters. Also, half the maximal inhibitory concentration (IC50) of the RNase inhibitor was successfully measured in the same volume of droplets at a frequency of 40 hertz.


Assuntos
Técnicas Analíticas Microfluídicas , Ribonucleases/análise , Etídio , Fluorescência , Humanos , RNA
13.
Bioprocess Biosyst Eng ; 40(8): 1151-1161, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28526899

RESUMO

This study introduces activated carbon (AC) as an effective anode for microbial fuel cells (MFCs) using real industrial wastewater without treatment or addition of external microorganism mediators. Inexpensive activated carbon is introduced as a proper electrode alternative to carbon cloth and carbon paper materials, which are considered too expensive for the large-scale application of MFCs. AC has a porous interconnected structure with a high bio-available surface area. The large surface area, in addition to the high macro porosity, facilitates the high performance by reducing electron transfer resistance. Extensive characterization, including surface morphology, material chemistry, surface area, mechanical strength and biofilm adhesion, was conducted to confirm the effectiveness of the AC material as an anode in MFCs. The electrochemical performance of AC was also compared to other anodes, i.e., Teflon-treated carbon cloth (CCT), Teflon-treated carbon paper (CPT), untreated carbon cloth (CC) and untreated carbon paper (CP). Initial tests of a single air-cathode MFC display a current density of 1792 mAm-2, which is approximately four times greater than the maximum value of the other anode materials. COD analyses and Coulombic efficiency (CE) measurements for AC-MFC show the greatest removal of organic compounds and the highest CE efficiency (60 and 71%, respectively). Overall, this study shows a new economical technique for power generation from real industrial wastewater with no treatment and using inexpensive electrode materials.


Assuntos
Eletrodos , Fontes de Energia Bioelétrica , Carbono , Eletricidade , Águas Residuárias
14.
Analyst ; 141(24): 6499-6502, 2016 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-27841380

RESUMO

Fluorescence polarization (FP) is a sensitive, robust, and homogeneous assay format, able to probe a diversity of biological molecules and their interactions. Herein, we describe a new FP strategy based on the use of streptavidin as a signal amplifier. Such signal amplified fluorescence polarization (SAFP) was used to monitor the binding affinity of human angiogenin and a single-stranded DNA aptamer. Streptavidin was bound to a biotinylated single-stranded DNA aptamer and the interaction between this complex and Alexa Fluor 488 labelled human angiogenin was measured. A dissociation constant of 135.3 ± 32.9 nM and a limit of detection of 6.3 nM were successfully extracted only when the FP signal was increased (without binding hindrance) via streptavidin. Moreover, the demonstrated approach was specific to target molecules without any non-specific binding. The streptavidin-triggered SAFP method unlike amplification strategies that utilize nanomaterials (such as graphene oxides, carbon nanotubes, and metal nanoparticles) is not compromised by fluorescence quenching, and it is able to operate within nanomolar concentration regimes. Furthermore, unlike the other FP signal amplification strategies that use dual binding DNA probes, the presented method is simple to implement with signal amplification only requiring the binding of streptavidin with biotinylated DNA. This method could be expanded to analyze molecular interactions and it may be a useful tool for FP measurement by reducing the concentration of rare and expensive protein samples.


Assuntos
Técnicas Biossensoriais , DNA/análise , Polarização de Fluorescência , Estreptavidina/química , Aptâmeros de Nucleotídeos/análise , Humanos , Ligação Proteica , Ribonuclease Pancreático/análise
15.
J Nanosci Nanotechnol ; 16(1): 595-600, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27398493

RESUMO

We report on the simple way of obtaining aligned poly(vinylidiene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers by electrospinning process. The collector drum rotation speed was adjusted to prepare well aligned PVDF-HFP nanofibers. The degree of alignment and the orientation of PVDF-HFP nanofibers can be significantly altered by varying the speed of collector drum rotation. The resultant PVDF-HFP nanofibers were systematically characterized. From the scanning electron microscopy data, it was found that the electrospun PVDF-HFP nanofibers were formed with well-aligned nature. The X-ray diffraction results revealed that the electrospun PVDF-HFP nanofibers with ß-phase can be formed by the increased collector drum rotation speed. Overall, the collector rotation speed during the electrospinning process plays an important role in obtaining well-aligned and improved characteristics of PVDF-HFP nanofibers.


Assuntos
Nanofibras/química , Polivinil/química
16.
Korean J Parasitol ; 52(5): 501-5, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25352698

RESUMO

In recent years, rapid diagnostic tests (RDTs) have been widely used for malaria detection, primarily because of their simple operation, fast results, and straightforward interpretation. The Asan EasyTest™ Malaria Pf/Pan Ag is one of the most commonly used malaria RDTs in several countries, including Korea and India. In this study, we tested the diagnostic performance of this RDT in Uganda to evaluate its usefulness for field diagnosis of malaria in this country. Microscopic and PCR analyses, and the Asan EasyTest™ Malaria Pf/Pan Ag rapid diagnostic test, were performed on blood samples from 185 individuals with suspected malaria in several villages in Uganda. Compared to the microscopic analysis, the sensitivity of the RDT to detect malaria infection was 95.8% and 83.3% for Plasmodium falciparum and non-P. falciparum, respectively. Although the diagnostic sensitivity of the RDT decreased when parasitemia was ≤500 parasites/µl, it showed 96.8% sensitivity (98.4% for P. falciparum and 93.8% for non-P. falciparum) in blood samples with parasitemia ≥100 parasites/µl. The specificity of the RDT was 97.3% for P. falciparum and 97.3% for non-P. falciparum. These results collectively suggest that the accuracy of the Asan EasyTest™ Malaria Pf/Pan Ag makes it an effective point-of-care diagnostic tool for malaria in Uganda.


Assuntos
Antígenos de Protozoários/isolamento & purificação , Malária Falciparum/diagnóstico , Adolescente , Adulto , Antígenos de Protozoários/sangue , Criança , Pré-Escolar , Humanos , Malária Falciparum/epidemiologia , Parasitemia , Sistemas Automatizados de Assistência Junto ao Leito , Valor Preditivo dos Testes , Kit de Reagentes para Diagnóstico , Sensibilidade e Especificidade , Uganda/epidemiologia , Adulto Jovem
17.
RSC Adv ; 14(47): 34904-34917, 2024 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-39483383

RESUMO

This study focuses on the development of cobalt-based organic nanofibers as efficient photocatalysts for hydrogen production via water splitting under visible light irradiation. The depletion of fossil fuels necessitates the exploration of alternative energy sources, with hydrogen emerging as a promising candidate due to its clean and renewable nature. While conventional photocatalysts have shown potential, their limited activity under visible light and fast electron-hole recombination hinder their efficiency. In this work, cobalt acetate/poly(vinyl alcohol) (CoAc/PVA) nanofibers were electrospun and treated in a novel reactor design under water gas atmosphere at 160 °C to produce continuous, smooth, and stable nanobelts. The nanofibers displayed a band gap energy of 2.29 eV, indicating strong absorption in the visible light range. Detailed characterization using FTIR, XPS, SEM, and TGA confirmed the formation of organic-inorganic hybrid nanofibers with uniform cobalt distribution. Hydrogen production experiments showed that the proposed nanofibers significantly outperformed Co3O4 nanofibers, with an optimal hydrogen generation rate of 3.266 mmol gcat -1 s-1 at 70 vol% methanol. Furthermore, the treated nanofibers demonstrated good stability over multiple cycles, maintaining a constant hydrogen production rate after the third run. The study highlights the advantages of cobalt-based organic nanofibers in overcoming the limitations of traditional photocatalysts, providing a novel route for sustainable hydrogen production.

18.
ACS Appl Mater Interfaces ; 16(8): 10238-10250, 2024 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-38372639

RESUMO

The electrochemical conversion of oxygen holds great promise in the development of sustainable energy for various applications, such as water electrolysis, regenerative fuel cells, and rechargeable metal-air batteries. Oxygen electrocatalysts are needed that are both highly efficient and affordable, since they can serve as alternatives to costly precious-metal-based catalysts. This aspect is particularly significant for their practical implementation on a large scale in the future. Herein, highly porous polyhedron-entrapped metal-organic framework (MOF)-assisted CoTe2/MnTe2 heterostructure one-dimensional nanorods were initially synthesized using a simple hydrothermal strategy and then transformed into ZIF-67 followed by tellurization which was used as a bifunctional electrocatalyst for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The designed MOF CoTe2/MnTe2 nanorod electrocatalyst exhibited superior activity for both OER (η = 220 mV@ 10 mA cm-2) and ORR (E1/2 = 0.81 V vs RHE) and outstanding stability. The exceptional achievement could be primarily credited to the porous structure, interconnected designs, and deliberately created deficiencies that enhanced the electrocatalytic activity for the OER/ORR. This improvement was predominantly due to the enhanced electrochemical surface area and charge transfer inherent in the materials. Therefore, this simple and cost-effective method can be used to produce highly active bifunctional oxygen electrocatalysts.

19.
J Nanosci Nanotechnol ; 13(7): 4686-93, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23901491

RESUMO

We report on the preparation and characterization of polyurethane (PU) nanofibers containing silver (Ag) nanoparticles were synthesized by using electrospinning. Two different approaches were adopted to incorporate the Ag nanoparticles in to PU nanofibers. In the first approach, a homogeneous solution of 10 wt% PU containing silver nitrate was electrospun to obtain PU-Ag composite nanofibers. And in the second approach, the pristine PU nanofibers were initially electrospun and then Ag nanoparticles were coated via wet casting method. The surface morphology, structure, bonding configuration, optical and thermal properties of the resultant products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV-vis spectroscopy and thermogravimetric analysis. The antibacterial activity was tested against four common food borne pathogenic bacteria, namely, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium and Klebsiella pneumoniae by minimum inhibitory concentration (MIC) method. Our results demonstrated that no bactericidal activity was detected for the pristine PU nanofibers. Further on, antibacterial activity was observed to be more pronounced for the composite nanofibers which were attributed to the presence of Ag nanoparticles in the composite nanofibers. Overall, this study demonstrates the fabrication of cheap, stable and effective nanofiber mats with excellent antimicrobial activity that can be utilized to inhibit the microbial growth associated with food stuff.


Assuntos
Fenômenos Fisiológicos Bacterianos/efeitos dos fármacos , Nanopartículas Metálicas/administração & dosagem , Nanopartículas Metálicas/química , Poliuretanos/química , Prata/química , Prata/farmacologia , Antibacterianos/farmacologia , Eletroquímica/métodos , Teste de Materiais , Rotação
20.
Front Chem ; 11: 1301172, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38025057

RESUMO

This manuscript is dedicated to a comprehensive exploration of the multifaceted challenge of fast electron-hole recombination in titanium dioxide photocatalysis, with a primary focus on its critical role in advancing the field of water photo splitting. To address this challenge, three prominent approaches-Schottky barriers, Z-scheme systems, and type II heterojunctions-were rigorously investigated for their potential to ameliorate TiO2's photocatalytic performance toward water photo splitting. Three distinct dopants-silver, cadmium oxide, and zinc oxide-were strategically employed. This research also delved into the dynamic interplay between these dopants, analyzing the synergetic effects that arise from binary and tertiary doping configurations. The results concluded that incorporation of Ag, CdO, and ZnO dopants effectively countered the fast electron-hole recombination problem in TiO2 NPs. Ag emerged as a critical contributor at higher temperatures, significantly enhancing photocatalytic performance. The photocatalytic system exhibited a departure from Arrhenius behavior, with an optimal temperature of 40°C. Binary doping systems, particularly those combining CdO and ZnO, demonstrated exceptional photocatalytic activity at lower temperatures. However, the ternary doping configuration involving Ag, CdO, and ZnO proved to be the most promising, surpassing many functional materials. In sum, this study offers valuable insights into how Schottky barriers, Z-scheme systems, and type II heterojunctions, in conjunction with specific dopants, can overcome the electron-hole recombination challenge in TiO2-based photocatalysis. The results underscore the potential of the proposed ternary doping system to revolutionize photocatalytic water splitting for efficient green hydrogen production, significantly advancing the field's understanding and potential for sustainable energy applications.

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