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1.
Indian J Nucl Med ; 38(3): 249-254, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38046972

RESUMO

Aims: The aim of this study was to evaluate the role of 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) scan in the detection of axillary lymph node (ALN) involvement and comparison with sentinel lymph node biopsy (SLNB) in operable early-stage breast cancer (EBC). Settings and Design: It is a retrospective analysis of staging PET-CT scan of EBC. Methods: A total of 128 patients with histopathologically proven breast cancer (BC) were included in the study. Preoperative mammography supplemented with ultrasonography and staging 18F-FDG PET-CT scan was done for all patients. Surgery was done within 30 (mean ± standard deviation = 13.8 ± 10.5) days of staging. SLNB was performed in patients without PET-positive ALNs. All patients with positive sentinel nodes and PET-positive ALNs underwent axillary lymph node dissection (ALND). Statistical Analysis Used: The comparison between categorical variables was made by Chi-square/Fisher's exact test as applicable. For continuous variables comparisons, Student's t-test and one-way analysis of variance tests were used. Results: Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PET-CT scan for detection of ALN involvement were 41.7%, 93.2%, 92.1%, and 45.6%, respectively. Sensitivity, specificity, PPV, and NPV of mammography were 84.5%, 54.5%, 78.0%, and 68.6%, respectively. Sixteen out of 46 (34.7%) patients with negative ALNs in PET-CT scan finally showed involvement in histopathology report after SLNB resulting in upstage of the disease. The size of tumor deposits in sentinel nodes was significantly smaller than PET-positive ALNs (P = 0.01). Our observations correlate with the results of earlier studies published in the literature. Conclusions: 18F-FDG PET-CT scan cannot substitute SLNB for ALN screening in EBC. The limitations are most marked in smaller and micrometastatic tumor deposits in ALNs and may be attributed to limitations of PET resolution. However, PET-positive nodes showed good specificity for disease involvement in our study. Therefore, ALND can safely be performed by omitting SLNB in such cases.

2.
Artigo em Inglês | MEDLINE | ID: mdl-37682510

RESUMO

In pursuit of a novel effective treatment for prostate cancer, methanolic extract of Stephania glabra tubers (Sg-ME) was utilized to fabricate silver (Sg-AgNP), copper oxide (Sg-CuONP), and silver-copper bimetallic nanoparticles (Sg-BNP). The characterization of the nanoparticles confirmed spherical shape with average diameters of 30.72, 32.19, and 25.59 nm of Sg-AgNP, Sg-CuONP, and Sg-BNP, respectively. Interestingly, these nanoparticles exhibited significant cytotoxicity toward the prostate cancer (PC3) cell line while being non-toxic toward normal cells. The nanoparticles were capable of inducing apoptosis in PC3 cells by enhancing reactive oxygen species (ROS) generation and mitochondrial depolarization. Furthermore, the shrinkage of 3D prostate tumor spheroids was observed after 4 days of treatment with these green nanoparticles. The 3D model system was less susceptible to nanoparticles as compared to the 2D model system. Sg-BNP showed the highest anticancer potential on 2D and 3D prostate cancer models.

3.
ACS Appl Mater Interfaces ; 15(22): 26563-26575, 2023 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-37227285

RESUMO

The ß-phase of the copolymer poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) possesses the highest dipole moment among all the functional polymers. It remains a key component of flexible energy-harvesting devices based on piezoelectricity and triboelectricity in the last decade. However, the quest for P(VDF-TrFE)-based magnetoelectric (ME) nanocomposites with enhanced ferroelectric, piezoelectric, and triboelectric properties remains elusive. The magnetostrictive inclusion in the copolymer matrix forms electrically conducting pathways and degrades ß-phase crystallinity significantly, deteriorating the functional properties of the nanocomposite films. To address this issue, we report the synthesis of magnetite (Fe3O4) nanoparticles on micron-scale magnesium hydroxide [Mg(OH)2] templates. These hierarchical structures were incorporated within the P(VDF-TrFE) matrix rendering composites with enhanced energy-harvesting capability. The Mg(OH)2 template prevents the formation of a continuous network of magnetic fillers, leading to lower electrical leakage in the composite. The addition of dual-phase fillers with 5 wt % only increases remanent polarization (Pr) values by ∼44%, owing to the presence of the ß-phase with significant crystallinity and increased interfacial polarization. The composite film exhibits a quasi-superparamagnetic nature and a significant magnetoelectric coupling coefficient (αME) of 30 mV/cm Oe. The film was also employed for triboelectric nanogenerator applications, exhibiting five times higher power density than the pristine film. We finally explored the integration of our ME devices with an internet of things platform to monitor the operational status of electrical appliances remotely. In light of these findings, the present work opens the path for future self-powered, multifunctional, and flexible ME devices with new application domains.

4.
Indian J Microbiol ; 63(1): 73-83, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37188239

RESUMO

Bacterial infection is a major crisis of 21st era and the emergence of multidrug resistant (MDR) pathogens cause significant health problems. We developed, green chemistry-based silver nanoparticles (G-Ag NPs) using Citrus pseudolimon fruit peel extract. G-Ag NPs has a spherical shape in the range of ~ 40 nm with a surface charge of - 31 Mv. This nano-bioagent is an eco-friendly tool to combat menace of MDR. Biochemical tests prove that G-Ag NPs are compatible with human red blood cells and peripheral blood mononuclear cells. There have been many reports on the synthesis of silver nanoparticles, but this study suggests a green technique for making non-cytotoxic, non-hemolytic organometallic silver nanoparticles with a high therapeutic index for possible use in the medical field. On the same line, G-Ag NPs are very effective against Mycobacterium sp. and MDR strains including Escherichia coli, Klebsiella species, Pseudomonas aeruginosa, and Acinetobacter baumannii isolated from patient samples. Based on it, we filed a patent to Indian Patent Office (reference no. 202111048797) which can revolutionize the prevention of biomedical device borne infections in hospital pre/post-operated cases. This work could be further explored in future by in vivo experimentation with mice model to direct its possible clinical utility. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01061-0.

5.
Environ Sci Pollut Res Int ; 30(12): 34054-34068, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36508093

RESUMO

The development of efficient nanomaterials with promising optical and surface properties for multifunctional applications has always been a subject of novel research. In this work, the study of highly efficient TiO2 nanorods (NRs) and Ta-doped TiO2 NRs (Ta-TiO2 NRs) synthesized by alkaline hydrothermal treatment followed by soaking treatment has been reported. NRs were investigated for their potential applications as recyclable/reproducible visible light active photocatalysts and surface-enhanced Raman scattering (SERS) substrates in wastewater treatment. NRs were characterized by various microscopic (scanning and transmission electron microscopy), spectroscopic (X-ray diffraction, X-ray photoelectron, UV-visible, photoluminescence, and Raman spectroscopy), and surface (Brunauer-Emmett-Teller) techniques. The NRs exhibited promising optical properties with a band gap of 2.95 eV (TiO2 NRs) and 2.58 eV (Ta-TiO2 NRs) showing excellent photo-degradation activities for methylene blue (MB) dye molecules under natural sunlight. Particularly, Ta-TiO2 NRs showed enhanced response as visible light active photocatalysts in normal sunlight and also as SERS substrate attributed to the additional defects introduced by Ta doping. It could be explained by the combined effect of doping-induced enhanced visible light absorption and charge transfer (CT) properties of Ta-TiO2 NRs. Furthermore, Ta-TiO2 NRs were investigated for their long-term stability, reproducibility of the data, and recyclability in view of their potential applications in water treatment.


Assuntos
Luz , Purificação da Água , Reprodutibilidade dos Testes , Titânio/química , Óxidos , Purificação da Água/métodos
6.
ACS Omega ; 7(34): 29728-29733, 2022 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-36061680

RESUMO

Visible-light-promoted cascade radical cyclization for the synthesis of sulfonylated benzimidazo/indolo[2,1-a]iso-quinolin-6(5H)-ones has been reported. The reaction provides transition-metal-free and expeditious access to sulfonylated polyaromatics. The use of sodium metabisulfite as a SO2 surrogate and the rapid generation of molecular complexity using a three-component photochemical protocol are the salient features of this reaction manifold.

7.
Biomater Adv ; 140: 213088, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36037763

RESUMO

Fluorescent probes based on semiconducting polymer nanoparticles (NPs) such as polyaniline (PANI) usually require external fluorophore doping to provide fluorescence function. Direct use of PANI-based NPs for bioimaging applications has been limited by PANI's weak blue fluorescence and aggregation-induced quenching in physiological medium. In this report, we developed a facile solid-state synthesis method to produce fluorescent polyaniline nanoparticles (FPNs) that are not only water-soluble but also exhibit high intensity and pH-sensitive red fluorescence. The FPNs showed high photoluminescence quantum yield (PLQY) of 19.3 % at physiological pH, which makes FPNs ideal for application as fluorescent nanoprobes in bioimaging. Moreover, we performed an in-depth study of photoluminescence dependence on pH and the phenomena of exciton-polaron quenching at low pH was highlighted. We also found that the ratio of emission intensity at 600 nm and 650 nm increased from 0.04 to 1.65 as pH was raised from 2.6 to 11.8, which could find its application in ratiometric pH sensing. FPNs exhibited excellent biocompatibility with >85 % cell viability for fibroblasts NIH/3 T3 and prostate cancer 22RV1 cells even at concentrations as high as 1000 µg/mL. In addition, fluorescence microscopy demonstrated concentration-dependent red fluorescence in the cytoplasm owing to the cellular uptake of FPNs in prostate cancer cells.


Assuntos
Nanopartículas , Neoplasias da Próstata , Compostos de Anilina , Corantes Fluorescentes , Humanos , Concentração de Íons de Hidrogênio , Masculino , Imagem Óptica
8.
Environ Res ; 212(Pt D): 113550, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35654159

RESUMO

Titanium dioxide (TiO2) has been considered as one of the most promising photocatalysts nanomaterials and is being used in a variety of fields of energy and environment under sunlight irradiation via photocatalysis. Highly efficient photocatalytic materials require the design of the proper structure with excellent morphology, interfacial structures, optical and surface properties, etc. Which are the key points to realize effective light-harvesting for photocatalytic applications. Hierarchical TiO2 based nanoflower structures (i.e., 3D nanostructures) possess such characteristics and have attracted much attention in recent years. The uniqueness of TiO2 nanoflowers (NFs) with a coarse texture and arranged structures demonstrates higher photocatalytic activity. This review deals with the hydrothermal synthesis of 3D TiO2 NFs and effect of shape/size as well as various key synthesis parameters to improve their optoelectronic and photocatalytic properties. Furthermore, to improve their photocatalytic properties, various strategies such as doping engineering and heterojunction/nanocomposite formation with other functional nanomaterials have been discussed followed by their potential applications in photocatalytic degradation of various emerging pollutants discharged into the wastewater from various sources. Importance of such 3D nanoarchitecutres and future research in other fields of current interest in environments are discussed.


Assuntos
Poluentes Ambientais , Nanocompostos , Purificação da Água , Catálise , Nanocompostos/química , Titânio/química
9.
Org Biomol Chem ; 20(22): 4522-4525, 2022 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-35605977

RESUMO

A visible-light-mediated synthesis of α,ß-diamino esters has been developed via the cross coupling of N,N-dimethylanilines with glyoxalic oxime ethers. This protocol involves the generation of α-aminoalkyl radicals under mild reaction conditions, provides α,ß-diamino esters in good to excellent yields, and can be performed on a gram-scale.


Assuntos
Ésteres , Éteres , Compostos de Anilina , Glioxal , Oximas
10.
Ann Med Surg (Lond) ; 73: 103111, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34976377

RESUMO

BACKGROUND AND OBJECTIVES: Pneumonia is the most common cause of death in children under five years of age. Epidemiological factors and the disease burden differ in developing and industrialized countries. The present study is a cross sectional observational study, carried out from August 2018 to August 2020 in Hindu Rao Hospital, to assess the prevalence of congenital heart disease (CHD) in patients with pneumonia in children up to 5 years. The main objectives of the study were to study the prevalence of congestive cardiac failure (CCF) in pneumonia with and without congenital heart disease. MATERIAL AND METHODS: Patients under 5 years of age, presenting with pneumonia during August 2018 to July 2020 were enrolled for study. The bio-data of each patient was documented each patient was clinically evaluated thoroughly and findings noted. Pneumonia was diagnosed on typical history, physical findings, blood investigations and chest radiographic finding of pneumonia infiltrates in either one or both lung fields. All the cases of pneumonia underwent transthoracic 2 Dimensional (2D) and Doppler echocardiography, done by the cardiologist. Any congenital heart disease so found was noted. The type and size of the defects was documented. The ventricular septal defects were classified based on the site and size. The size of the patient ductus arteriosus was also determined. These measurements were taken to evaluate the impact of defect size on pneumonia. CCF was diagnosed when the patient fulfilled the clinical diagnostic criteria of heart failure. All the cases of pneumonia underwent transthoracic 2 Dimensional (2D) and Doppler echocardiography for diagnosis of any congenital heart disease. RESULTS: Mean age of the children with pneumonia was 9.94 months with 77.5% of the cases below 1 year of age. Male predominance was seen with 56.3% males to 43.8% females. Prevalence of congenital heart disease among cases of pneumonia was 12.5% while that of congestive heart failure was 27.5%. Most common CHD observed was VSD (14 cases; 8.8%) followed by PDA, ASD and TGA (4; 2.5% and 3; 1.9% and 1; 0.6% cases respectively). A significant association was observed between presence of congenital heart disease and development of CCF. CONCLUSION: Our study demonstrates that most patients with pneumonia or recurrent pneumonia are likely to have an underlying illness at the time of pneumonia. Recurrent ALRTI often occurred in children with history of congenital heart diseases (CHD) and is also associated with Congestive Cardiac Failure. Children with CHD are more vulnerable to recurrent respiratory tract infection.

12.
ACS Pharmacol Transl Sci ; 4(1): 8-54, 2021 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-33615160

RESUMO

The ongoing worldwide pandemic due to COVID-19 has created awareness toward ensuring best practices to avoid the spread of microorganisms. In this regard, the research on creating a surface which destroys or inhibits the adherence of microbial/viral entities has gained renewed interest. Although many research reports are available on the antibacterial materials or coatings, there is a relatively small amount of data available on the use of antiviral materials. However, with more research geared toward this area, new information is being added to the literature every day. The combination of antibacterial and antiviral chemical entities represents a potentially path-breaking intervention to mitigate the spread of disease-causing agents. In this review, we have surveyed antibacterial and antiviral materials of various classes such as small-molecule organics, synthetic and biodegradable polymers, silver, TiO2, and copper-derived chemicals. The surface protection mechanisms of the materials against the pathogen colonies are discussed in detail, which highlights the key differences that could determine the parameters that would govern the future development of advanced antibacterial and antiviral materials and surfaces.

13.
ACS Appl Nano Mater ; 4(2): 911-948, 2021 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-37556236

RESUMO

The COVID-19 outbreak has exposed the world's preparation to fight against unknown/unexplored infectious and life-threatening pathogens. The unavailability of vaccines, slow or sometimes unreliable real-time virus/bacteria detection techniques, insufficient personal protective equipment (PPE), and a shortage of ventilators and many other transportation equipments have further raised serious concerns. Material research has been playing a pivotal role in developing antimicrobial agents for water treatment and photodynamic therapy, fast and ultrasensitive biosensors for virus/biomarkers detection, as well as for relevant biomedical and environmental applications. It has been noticed that these research efforts nowadays primarily focus on the nanomaterials-based platforms owing to their simplicity, reliability, and feasibility. In particular, nanostructured fluorescent materials have shown key potential due to their fascinating optical and unique properties at the nanoscale to combat against a COVID-19 kind of pandemic. Keeping these points in mind, this review attempts to give a perspective on the four key fluorescent materials of different families, including carbon dots, metal nanoclusters, aggregation-induced-emission luminogens, and MXenes, which possess great potential for the development of ultrasensitive biosensors and infective antimicrobial agents to fight against various infections/diseases. Particular emphasis has been given to the biomedical and environmental applications that are linked directly or indirectly to the efforts in combating COVID-19 pandemics. This review also aims to raise the awareness of researchers and scientists across the world to utilize such powerful materials in tackling similar pandemics in future.

14.
Artigo em Inglês | MEDLINE | ID: mdl-33137846

RESUMO

Two-dimensional (2D) metal organic frameworks (MOFs), are an emerging class of layered nanomaterials with well-defined structure and modular composition. The unique pore structure, high flexibility, tunability, and ability to introduce desired functionality within the structural framework, have led to potential use of MOFs in biomedical applications. This article critically reviews the application of 2D MOFs for therapeutic delivery, tissue engineering, bioimaging, and biosensing. Further, discussion on the challenges and strategies in next generation of 2D MOFs are also included. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.


Assuntos
Estruturas Metalorgânicas , Nanoestruturas , Técnicas Biossensoriais , Diagnóstico por Imagem , Sistemas de Liberação de Medicamentos , Engenharia Tecidual
15.
Int J Biol Macromol ; 148: 1130-1139, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31954790

RESUMO

Herein, porous sodium alginate/graphite based hybrid hydrogel was fabricated as an effective adsorbent for organic pollutant. Sodium alginate was modified through graft polymerization of acrylic acid and subsequently loaded with graphite powder to enhance its adsorption capability. The synthesized sodium alginate cross-linked acrylic acid/graphite (NaA-cl-AAc/GP) hydrogel composite was utilized in the removal of malachite green (MG) dye from aqueous solution using batch adsorption experiments. The NaA-cl-AAc/GP hydrogel composite was characterized by infrared spectroscopy, Raman spectroscopy, thermo-gravimetric analysis, scanning electron microscopy, x-ray photoelectron spectroscopy and x-ray diffraction. Under optimized experimental conditions, a maximum adsorption capacity of 628.93 mg g-1 was attained for malachite green dye. Moreover, the adsorption process could be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. The hydrogel composite also showed 91% adsorption after three consecutive cycles of dye adsorption-desorption. Therefore, the NaA-cl-AAc/GP hydrogel composite is a potentially favourable material towards dye pollution remediation owing to its better swelling rate, environment friendliness, high adsorption potential and regeneration capability.


Assuntos
Alginatos/química , Grafite/química , Hidrogéis/química , Corantes de Rosanilina/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Estrutura Molecular , Análise Espectral , Poluentes Químicos da Água/química
16.
J Nanosci Nanotechnol ; 20(6): 3710-3717, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31748068

RESUMO

Exceptional progress in the performance of perovskite solar cells in a very short time has made it a potential photovoltaic technology for future deployment. The compositional engineering in perovskite materials and other buffer layers makes it a feasible candidate for commercial applications in the near future. However, there are certain challenges associated with these devices which need to be addressed such as device stability, process dependent device efficiency, hole transport layer (HTL) etc. The device performance is highly dependent on the processing parameters of the precursors. Understanding the origin of this challenge is very crucial for reproducible device performance. In this work, we have focused on utilizing NiO as a HTL in planar perovskite solar cells and studied the ageing effect of NiO precursor solution on the perovskite film quality in terms of crystallinity, grain growth, surface morphology, and overall device performance. It is observed that the ageing of NiO precursor promotes the formation of NiO films with increased roughness which improves the perovskite film quality. Structural and morphological studies revealed that the perovskite films formed on aged NiO films were highly crystalline in nature, uniform and with larger grain size. Current- voltage characteristics under illumination show that the films casted from NiO aged solution are better for perovskite solar cell applications and result in reduced parasitic resistances and enhanced charge transport.

17.
Nanoscale ; 11(44): 21404-21418, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31674610

RESUMO

Mechanistic studies, utilizing molecular dynamics (MD) and density functional theory (DFT) calculations, were undertaken to provide a molecular level explanation of Ba cation segregation in double perovskite GdBaCo2O5+δ (GBCO) electrodes. The energy (γ) of the terminal surface having only Ba cations, indicated the surface to be the most stable (γ = 6.7 kJ mol-1Å-2) as compared to the other surfaces. MD simulations elaborated on the cation disorder in the near surface region where Ba cations in the subsurface region were observed to migrate towards the surface. This led to a disruption in cation ordering with a propensity to form multiphases in the near surface region. In the near surface zone, oxygen anion diffusivity was observed to be reduced by an order of magnitude (D = 1.6 × 10-11 cm2 s-1 at 873 K) as compared to the bulk oxygen anion diffusivity value (D = 1.96 × 10-10 cm2 s-1 at 873 K). A novel idea was then proposed to control the degree of surface segregation of Ba cations by applying nanostructuring of the GBCO material in the form of nanoparticles. MD simulations elucidated that the near surface region having a high degree of cation disorder in the nanostructured GBCO may regain back the oxygen anion diffusivity value (D = 3.98 × 10-10 cm2 s-1, at 873 K) comparable to the bulk core region (D = 2.51 × 10-10 cm2 s-1, at 873 K). A proof of concept experiment was setup to test this hypothesis. The electrochemical performance of the electrode, fabricated using GBCO nanoparticles, was measured to improve by 15% as compared to the electrode synthesized with a bulk size GBCO material. This was attributed to the control in Ba-cation segregation, obtained on nanostructuring which resulted in higher oxygen anion transport in the near-surface region of the electrode material. XPS characterization of the surface of the nanostructured GBCO materials supported this assertion.

18.
ACS Appl Mater Interfaces ; 11(41): 38177-38189, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31580638

RESUMO

For a variety of mechanical energy harvesting as well as biomedical device applications, flexible energy devices are useful which require the development of environment-friendly and robust materials and devices. In this manuscript, we demonstrate a lead-free, facile, low-cost, sol-gel-processed reduced graphene oxide (rGO)/P(VDF-TrFE) nanocomposite with multipurpose capability demonstration as a piezoelectric nanogenerator (PENG) and hybrid piezoelectric triboelectric nanogenerator (HPTENG) devices. The structural analysis of the materials shows that the interactions between the rGO and P(VDF-TrFE) matrix help in breaking the centrosymmetry of rGO, resulting in a strong enhancement in the piezoelectric, ferroelectric, and triboelectric properties of composites over pristine P(VDF-TrFE) films. In the case of PENG, the composite devices showed >22 times improvement in the piezoelectric output voltage over the pristine P(VDF-TrFE) PENG device with the highest output voltage of 89.7 V for the 0.5 wt % rGO composite. Also, HPTENG devices based on composite films generated an average VOC of 227 V, much higher than the pristine P(VDF-TrFE)-based devices. Maximum output power densities measured were 0.28 W/cm3 and 0.34 mW/cm3 for hybrid piezoelectric-triboelectric and piezoelectric devices, respectively. The triboelectric devices demonstrated lighting of 45 blue light-emitting diodes directly, connected in series, by harvesting mechanical energy generated by repeated finger tapping. The study highlights the promise of rGO/P(VDF-TrFE) composites for PENG and HPTENG devices with dramatically improved electrical output.

19.
ACS Omega ; 4(2): 3257-3267, 2019 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-31459542

RESUMO

Here, we report a facile and easily scalable hydrothermal synthetic strategy to synthesize Ni-V layered double hydroxide (NiV LDH) nanosheets toward high-energy and high-power-density supercapacitor applications. NiV LDH nanosheets with varying Ni-to-V ratios were prepared. Three-dimensional curved nanosheets of Ni0.80V0.20 LDH showed better electrochemical performance compared to other synthesized NiV LDHs. The electrode coated with Ni0.80V0.20 LDH nanosheets in a three-electrode cell configuration showed excellent pseudocapacitive behavior, having a high specific capacity of 711 C g-1 (1581 F g-1) at a current density of 1 A g-1 in 2 M KOH. The material showed an excellent rate capability and retained the high specific capacity of 549 C g-1 (1220 F g-1) at a current density of 10 A g-1 and low internal resistances. Owing to its superior performance, Ni0.80V0.20 LDH nanosheets were used as positive electrode and commercial activated carbon was used as negative electrode for constructing a hybrid supercapacitor (HSC) device, having a working voltage of 1.5 V. The HSC device exhibited a high specific capacitance of 98 F g-1 at a current density of 1 A g-1. The HSC device showed a higher energy density of 30.6 Wh kg-1 at a power density of 0.78 kW kg-1 and maintained a high value of 24 Wh kg-1 when the power density was increased to 11.1 kW kg-1. The performance of NiV LDHs nanosheets indicates their great potential as low-cost electrode material for future energy-storage devices.

20.
ACS Appl Mater Interfaces ; 11(15): 14329-14339, 2019 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-30892860

RESUMO

Dielectric polymer nanocomposites with a high breakdown field and high dielectric constant have drawn significant attention in modern electrical and electronic industries due to their potential applications in dielectric and energy storage systems. The interfaces of the nanomaterials play a significant role in improving the dielectric performance of polymer nanocomposites. In this work, polydopamine (dopa)-functionalized TiO2-BaTiO3-TiO2 (TiO2-BT-TiO2@dopa) core@double-shell nanoparticles have been developed as novel nanofillers for high-energy-density capacitor applications. The hierarchically designed nanofillers help in tailoring the interfaces surrounding the polymer matrix as well as act as individual capacitors in which the core and outer TiO2 shell function as a capacitor plate because of their high electrical conductivity while the middle BT layer functions as a dielectric medium due to high dielectric constant. Detailed electrical characterizations have revealed that TiO2-BT-TiO2@dopa/poly(vinylidene fluoride) (PVDF) possesses a higher relative dielectric permittivity (εr), breakdown strength ( Eb), and energy density as compared to those of PVDF, TiO2/PVDF, TiO2@dopa/PVDF, and TiO2-BT@dopa/PVDF polymer nanocomposites. The εr and energy density of TiO2-BT-TiO2@dopa/PVDF were 12.6 at 1 kHz and 4.4 J cm-3 at 3128 kV cm-1, respectively, which were comparatively much higher than those of commercially available biaxially oriented polypropylene having εr of 2.2 and the energy density of 1.2 J cm-3 at a much higher electric field of 6400 kV cm-1. It is expected that these results will further open new avenues for the design of novel architecture for high-performance polymer nanocomposite-based capacitors having core@multishell nanofillers with tailored interfaces.

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