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1.
Small ; 20(28): e2309321, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38528424

RESUMEN

A paucity of redox centers, poor charge transport properties, and low structural stability of organic materials obstruct their use in practical applications. Herein, these issues have been addressed through the use of a redox-active salen-based framework polymer (RSFP) containing multiple redox-active centers in π-conjugated configuration for applications in lithium-ion batteries (LIBs). Based on its unique architecture, RSFP exhibits a superior reversible capacity of 671.8 mAh g-1 at 0.05 A g-1 after 168 charge-discharge cycles. Importantly, the lithiation/de-lithiation performance is enhanced during operation, leading to an unprecedented reversible capacity of 946.2 mAh g-1 after 3500 cycles at 2 A g-1. The structural evolution of RSFP is studied ex situ using X-ray photoelectron spectroscopy, revealing multiple active C═N, C─O, and C═O sites and aromatic sites such as benzene rings. Remarkably, the emergence of C═O originated from C─O is triggered by an electrochemical process, which is beneficial for improving reversible lithiation/delithiation behavior. Furthermore, the respective strong and weak binding interactions between redox centers and lithium ions, corresponding to theoretical capacities of 670.1 and 938.2 mAh g-1, have been identified by density functional theory calculations manifesting 14-electron redox reactions. This work sheds new light on routes for the development of redox-active organic materials for energy storage applications.

2.
Langmuir ; 40(8): 4063-4076, 2024 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-38354294

RESUMEN

Highly efficient nanocatalysts with a high specific surface area were successfully synthesized by a cost-effective and environmentally friendly hydrothermal method. Structural and elemental purity, size, morphology, specific surface area, and band gap of pristine and 1 to 5% Cu-doped TiO2 nanoparticles were characterized by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), energy dispersive X-ray analysis (EDAX), inductively coupled plasma mass spectrometry (ICP-MS), liquid chromatography-high resolution mass spectrometry (LC-HRMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET surface area, Raman spectroscopy, photoluminescence spectroscopy (PL) and UV-visible diffused reflectance spectroscopy (UV-DRS) studies. The XPS and EPR findings indicated the successful integration of Cu ions into the TiO2 lattice. UV-DRS and BET surface area investigations revealed that with an increase in dopant concentration, Cu-doped TiO2 NPs show a decrease in band gap (3.19-3.08 eV) and an increase in specific surface area (169.9-188.2 m2/g). Among all compositions, 2.5% Cu-doped TiO2 has shown significant H2 evolution with an apparent quantum yield of 17.67%. Furthermore, the electrochemical water-splitting study shows that 5% Cu-doped TiO2 NPs have superiority over pristine TiO2 for H2 evolution reaction. It was thus revealed that the band gap tuning with the desired dopant concentration led to enhanced photo/electrocatalytic sustainable energy applications.

3.
Nanotechnology ; 35(44)2024 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-39025084

RESUMEN

Hydrothermally derived nanocubes of CeO2(10 nm) were explored as an efficient heterogeneous catalyst in the partial oxidation of aromatic alcohols to the corresponding aldehydes and aerobic oxidation ofp-nitrotoluene top-nitrobenzoic acid. The CeO2nanocatalyst was characterized by x-ray diffraction, transmission electron microscopy (TEM), energy dispersive spectroscopy, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis, Fourier transform infrared spectroscopy, thermal gravimetric analysis and ultraviolet-visible spectroscopy. TEM/high-resolution TEM micrographs reveal a morphology of mostly cubic nanostructures with exposed highly active {100} and {110} facets. The surface area of nanoceria was determined by BET analysis and found to be 33.8 m2g-1. To demonstrate the universality of the catalytic system, the selective oxidation of different substrates of benzylic alcohol and complete oxidation ofp-nitrotoluene was investigated under mild conditions. Absolute selectivity towards their respective aldehydes was found to be 99.50% (benzaldehyde), 90.18% (p-chlorobenzaldehyde), 99.71% (p-nitrobenzaldehyde), 98.10% (p-fluorobenzaldehyde), 94.66% (p-anisaldehyde) and 86.14% (cinnamaldehyde). Moreover, the catalytic oxidative transformation of nitrotoluene results in 100% conversion with 99.29% selectivity towards nitrobenzoic acid.

4.
Environ Res ; 241: 117669, 2024 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-37980993

RESUMEN

The current work concentrates on the fabrication of Ga doped Co0.6Cu0.4Fe2O4 nanocatalysts via sol-gel auto-combustion (SGA) for the production of green and sustainable source of energy i.e., hydrogen through photocatalytic and electrocatalytic routes. Single-phased cubic crystal structure with Fd3m geometry was observed through XRD patterns. FESEM images show the aggregated and spherical shaped grains with distinct grain boundaries and average grain size of 1.04 and 1.39 µm for the Co0.6Cu0.4Fe2O4, and Co0.6Cu0.4Ga0.02Fe1.98O4 nanomaterials. Soft magnetic behaviour with a coercivity (Hc) and saturation magnetization (Ms) of 235.32-357.26 Oe and 54.65-61.11 emu/g was obtained for the produced nanomaterials. The estimation of photocatalytic nature for generating H2 was conducted using the sacrificial agents i.e., 0.128 M Na2S and 0.079 M Na2SO3. The analysis focused on measuring the maximum H2 generation was achieved by photocatalysts throughout three consecutive 4-h cycles. Out of all compositions, Co0.6Cu0.4Ga0.02Fe1.98O4 nanomaterial have the highest photocatalytic activity of 16.71 mmol gcat-1. However, the electrocatalytic behaviour of prepared Co0.6Cu0.4GaxFe2-xO4 (x = 0.00-0.03) electrocatalysts were determined for HER (Hydrogen evolution reaction) reaction. The overpotential values of Co0.6Cu0.4Fe2O4, Co0.6Cu0.4Ga0.01Fe1.99O4, Co0.6Cu0.4Ga0.02Fe1.98O4, and Co0.6Cu0.4Ga0.03Fe1.97O4 catalysts at 10 mA cm-2 were -0.81, -0.85, -1.03, and 1.21 V, correspondingly. Thus, at cathode current density of 10 mA/cm-2, an elevation in overpotential was noted, which indicates that the undoped Co0.6Cu0.4Fe2O4 (x = 0.00) electrocatalyst have remarkable electrocatalytic HER activity. Consequently, owing to photo/electro catalytic water splitting traits, the prepared catalysts are highly efficient for the green hydrogen generation.


Asunto(s)
Hidrógeno , Nanoestructuras , Catálisis , Electrodos , Fenotipo
5.
Sci Technol Adv Mater ; 25(1): 2292485, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38259326

RESUMEN

Among various metal-organic frameworks (MOFs), the zeolitic imidazole framework (ZIF), constructed by the regular arrangement of 2-methylimidazole and metal ions, has garnered significant attention due to its distinctive crystals and pore structures. Variations in the sizes and shapes of ZIF crystals have been reported by changing the synthesis parameters, such as the molar ratios of organic ligands to metal ions, choice of solvents, and temperatures. Nonetheless, the giant ZIF-8 single crystals beyond the typical range have rarely been reported. Herein, we present the synthesis of millimeter-scale single crystal ZIF-8 using the solvothermal method in N,N-diethylformamide. The resulting 1-mm single crystal is carefully characterized through N2 adsorption-desorption isotherms, scanning electron microscopy, and other analytical techniques. Additionally, single-crystal X-ray diffraction is employed to comprehensively investigate the framework's mobility at various temperatures.


Millimeter-sized ZIF-8 single crystals were synthesized using the solvothermal method. These crystals exhibit a notable BET surface area of 1681 m2∙g−1 and demonstrate a reversible change in their crystal structure.

6.
Int J Mol Sci ; 25(15)2024 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-39125609

RESUMEN

Environmentally friendly biosynthesis of silver nanoparticles (AgNPs) from Aeonium arboreum (L.) Webb & Berthel is reported for the first time. The synthesized AgNPs were characterized using UV-Vis, FTIR, TEM, Zeta potential, and XRD analysis, revealing high stability (-29.1 mV), spherical shape, and an average size of 100 nm. The antimicrobial activity levels of both A. arboreum extract and biosynthesized AgNPs were evaluated against five uropathogens (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans). Both the extract and the AgNPs exhibited significant efficacy, particularly against E. coli, with inhibition zones of 27 mm and 30 mm, respectively. LC-MS analysis tentatively identified 11 secondary metabolites in the extract, including quercetin-3-O-glucoside, quercetin-3-O-rhamnoside, myricetin 3-glucoside, and daphneresinol. In silico docking studies revealed promising binding affinities of these metabolites in relation to key enzymes involved in bacterial folate synthesis (dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS)) and DNA replication (DNA gyrase). These findings demonstrate the potential of A. arboreum-based AgNPs and their associated metabolites as a novel therapeutic approach for combating urinary tract infections. Their antimicrobial, antihemolytic, and antibiofilm properties warrant further investigation.


Asunto(s)
Biopelículas , Nanopartículas del Metal , Pruebas de Sensibilidad Microbiana , Simulación del Acoplamiento Molecular , Plata , Nanopartículas del Metal/química , Plata/química , Plata/farmacología , Biopelículas/efectos de los fármacos , Extractos Vegetales/química , Extractos Vegetales/farmacología , Antiinfecciosos/farmacología , Antiinfecciosos/química , Antibacterianos/farmacología , Antibacterianos/química , Candida albicans/efectos de los fármacos , Pseudomonas aeruginosa/efectos de los fármacos , Simulación por Computador
7.
Medicina (Kaunas) ; 60(8)2024 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-39202625

RESUMEN

Background and Objectives: The frequency of multidrug-resistant Klebsiella pneumoniae (MDRKP) has dramatically increased worldwide in recent decades, posing an urgent threat to public health. The aim of this study was to assess the extent of K. pneumoniae in the Aseer region and explore the corresponding antimicrobial resistance profile over the last ten years. Materials and Methods: A record-based retrospective study was conducted in a tertiary hospital during the period of 2013 to 2022. The study targeted laboratory samples taken from patients admitted to the hospital and sent for K. pneumoniae culturing. We included only samples taken from the patient and confirmed by the lab. Data were extracted using a pre-structured data extraction sheet to avoid data-collection bias and confirm the inter-rater precision. Statistical Package for Social Sciences (SPSS) version 26 was employed for statistical analysis. All relationships were tested using Pearson X2 test for categorical data or chi-square for linear trend for resistance rate over years. Results: We obtained 3921 samples of isolated K. pneumoniae out of 28,420 bacterial samples. The isolation rate began at 11.3% in 2013, decreased to 6.1% in 2016, and then increased to a peak of 16.3% in 2021, before slightly decreasing to 12.8% in 2022. In total, 23.7% of K. pneumoniae samples were identified in urine samples, 19% in sputum samples, 14% in wound samples, and 11.7% in blood samples. The overall antibiotic resistance rate of K. pneumoniae from 2013 to 2022 showed a significant increase, particularly during 2020 and 2021, before decreasing again in 2022. The resistance rate decreased from 22.2% in 2013 to 18.6% in 2016 and increased to 54.6% and 56.4% during 2020 and 2021, respectively (p = 0.039). Conclusions: We observed a significant shift in K. pneumoniae resistance for some antibiotics during the study period, highlighting the urgent need for enhanced antimicrobial stewardship and infection-control measures.


Asunto(s)
Antibacterianos , Infecciones por Klebsiella , Klebsiella pneumoniae , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/aislamiento & purificación , Humanos , Arabia Saudita/epidemiología , Estudios Retrospectivos , Infecciones por Klebsiella/epidemiología , Infecciones por Klebsiella/tratamiento farmacológico , Masculino , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Femenino , Persona de Mediana Edad , Pruebas de Sensibilidad Microbiana , Centros de Atención Terciaria/estadística & datos numéricos , Adulto , Farmacorresistencia Bacteriana Múltiple , Anciano
8.
Environ Res ; 238(Pt 1): 117086, 2023 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-37683783

RESUMEN

Psoriasis is a deleterious auto-immune disorder which seriously harms the patients physical and mental health. CD44 are found to be over-expressed on psoriatic lesions which are highly responsible for epidermal hyperproliferation and inflammation. Gallic acid (GA), a phenolic acid natural compound has potential inhibitory impact on pro-inflammatory transcription factors. However, the penetration across skin and availability is low when applied topically, making the treatment extremely challenging. Considering such factors, we developed GA loaded chitosan nanoparticles and modified with hyaluronic acid (HA) (HA@CS-GA NP) to assess the therapeutic potential against psoriasis. The formulations were characterized by DSC, zetasizer and TEM for assuring the development of nanosystems. GA loaded CS NP had a particle size of 207.2 ± 0.08 nm while after coating with HA, the size increased to 220.1 ± 0.18 nm. The entrapment efficiency was 93.24 ± 0.132% and drug loading of 73.17 ± 0.23%. The in vitro cell viability assessment study confirmed enhanced anti-proliferative effect of HA@CS-GA NP over plain GA which is due to high sensitivity towards HaCaT cell. The in vivo results on imiquimod induced psoriasis model indicated that CD44 receptor mediated targeted approach of HA@CS-GA NP gel had great potential in restricting the keratinocyte hyperproliferation and circumventing psoriasis. For the therapy of further skin-related conditions, HA modified nanoparticles should be investigated extensively employing genes, antibodies, chemotherapeutics, or natural substances.


Asunto(s)
Quitosano , Nanopartículas , Psoriasis , Humanos , Ácido Hialurónico/uso terapéutico , Ácido Gálico , Psoriasis/tratamiento farmacológico
9.
Environ Res ; 237(Pt 1): 116894, 2023 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-37586450

RESUMEN

Lyotropic liquid crystals are self-assembled, non-lamellar, and mesophase nanostructured materials that have garnered significant attention as drug carriers. Cubosomes, a subtype of lyotropic liquid crystalline nanoparticles, possess three-dimensional structures that display bicontinuous cubic liquid-crystalline patterns. These patterns are formed through the self-organization of unsaturated monoglycerides (amphphilic lipids such as glyceryl monooleate or phytantriol), followed by stabilization using steric polymers (poloxamers). Owing to their bicontinuous structure and steric polymer-based stabilization, cubosomes have been demonstrated to possess greater entrapment efficiency for hydrophobic drugs compared to liposomes, while also exhibiting high stability. In the past decade, there has been significant interest in cubosomes due to their ability to deliver therapeutic and contrast agents for cancer treatment and imaging with minimal side effects, establishing them as a safe and effective approach. Concerning these advantages, the present review elaborates on the general aspects, composition, and preparation techniques of cubosomes, followed by explanations of their mechanisms of drug loading and release patterns. Furthermore, the review provides meticulous discussions on the use of cubosomes in the treatment and imaging of various types of cancer, culminating in the enumeration of patents related to cubosome-based drug delivery systems.

10.
Molecules ; 28(10)2023 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-37241923

RESUMEN

Infectious diseases caused by viruses and bacteria are a major public health concern worldwide, with the emergence of antibiotic resistance, biofilm-forming bacteria, viral epidemics, and the lack of effective antibacterial and antiviral agents exacerbating the problem. In an effort to search for new antimicrobial agents, this study aimed to screen antibacterial and antiviral activity of the total methanol extract and its various fractions of Pulicaria crispa (P. crispa) aerial parts. The P. crispa hexane fraction (HF) was found to have the strongest antibacterial effect against both Gram-positive and Gram-negative bacteria, including biofilm producers. The HF fraction reduced the expression levels of penicillin binding protein (PBP2A) and DNA gyrase B enzymes in Staphylococcus aureus and Pseudomonas aeruginosa, respectively. Additionally, the HF fraction displayed the most potent antiviral activity, especially against influenza A virus, affecting different stages of the virus lifecycle. Gas chromatography/mass spectrometry (GC/MS) analysis of the HF fraction identified 27 compounds, mainly belonging to the sterol class, with ß-sitosterol, phytol, stigmasterol, and lupeol as the most abundant compounds. The in silico study revealed that these compounds were active against influenza A nucleoprotein and polymerase, PBP2A, and DNA gyrase B. Overall, this study provides valuable insights into the chemical composition and mechanism of action of the P. crispa HF fraction, which may lead to the development of more effective treatments for bacterial and viral infections.


Asunto(s)
Asteraceae , Pulicaria , Virus , Antibacterianos/farmacología , Antibacterianos/química , Antivirales/farmacología , Pulicaria/química , Girasa de ADN/farmacología , Bacterias Gramnegativas , Bacterias Grampositivas , Pruebas de Sensibilidad Microbiana , Bacterias , Biopelículas , Extractos Vegetales/farmacología , Extractos Vegetales/química
11.
Nanotechnology ; 33(14)2022 Jan 12.
Artículo en Inglés | MEDLINE | ID: mdl-34915455

RESUMEN

Metal oxides are well-known materials that have been considered as the prominent photocatalysts. Photocatalysis is a promising way to address the environmental issues which are caused by fossil fuel the combustion and industrial pollutants. Lot of efforts such as doping of metal oxides with metals, non-metals have been made to enhance their photocatalytic activity. More specifically, in this review we have discussed detailed synthesis procedures of rare earth doped metal oxides performed in the past decades. The advantage of doping metal oxides with rare earth metals is that they readily combine with functional groups due to the 4f vacant orbitals. Moreover, doping rare earth metals causes absorbance shift to the visible region of the electromagnetic spectrum which results to show prominent photocatalysis in this region. The effect of rare earth doping on different parameters of metal oxides such as band gap and charge carrier recombination rate has been made in great details. In perspective section, we have given a brief description about how researchers can improve the photocatalytic efficiencies of different metal oxides in coming future. The strategies and outcomes outlined in this review are expected to stimulate the search for a whole new set of rare earth doped metal oxides for efficient photocatalytic applications.

12.
Nanotechnology ; 33(35)2022 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-35580560

RESUMEN

Semiconductor photocatalysis has gained considerable attention in recent years due to their enabling nature to convert solar energy into fuels of renewable hydrocarbon. However, many of them suffer from some drawbacks like the inability to visible light irradiation and wide band gaps. Herein, we have synthesized monophasic strontium (Sr) doped SnO2nanoparticles by a cost-effective and environmental friendly hydrothermal method. As-synthesized nanoparticles showed rutile crystalline structure with irregular and rough cubical shape and no other elemental impurities. Sr-doped SnO2nanoparticles show a constant decrease in bandgap with increasing dopant concentration, which is estimated for excellent photocatalytic activity. The photocatalytic water splitting of as-prepared Sr-doped SnO2nanoparticles for H2generation shows a large influence of the increasing dopant concentration related to the narrowing bandgap on H2generation rate. Hence, the tunable bandgap with adjusted dopant concentration indicates that band gap tuning through doping for produced nanostructures may open up a new opportunities for photocatalytic and other optoelectronic applications.

13.
Environ Res ; 214(Pt 3): 113995, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-35932830

RESUMEN

Air pollution is becoming a distinctly growing concern and the most pressing universal problem as a result of increased energy consumption, with the multiplication of the human population and industrial enterprises, resulting in the generation of hazardous pollutants. Among these, carbon monoxide, nitrogen oxides, Volatile organic compounds, Semi volatile organic compounds, and other inorganic gases not only have an adverse impact on human health both outdoors and indoors, but have also substantially altered the global climate, resulting in several calamities around the world. Thus, the purification of air is a crucial matter to deal with. Photocatalytic oxidation is one of the most recent and promising technologies, and it has been the subject of numerous studies over the past two decades. Hence, the photocatalyst is the most reassuring aspirant due to its adequate bandgap and exquisite stability. The process of photocatalysis has provided many benefits to the atmosphere by removing pollutants. In this review, our work focuses on four main themes. Firstly, we briefly elaborated on the general mechanism of air pollutant degradation, followed by an overview of the typical TiO2 photocatalyst, which is the most researched photocatalyst for photocatalytic destruction of gaseous VOCs. The influence of operating parameters influencing the process of photocatalytic oxidation (such as mass transfer, light source and intensity, pollutant concentration, and relative humidity) was then summarized. Afterwards, the progress and drawbacks of some typical photoreactors (including monolithic reactors, microreactors, optical fiber reactors, and packed bed reactors) were described and differentiated. Lastly, the most noteworthy coverage is dedicated to different types of modification strategies aimed at ameliorating the performance of photocatalysts for degradation of air pollutants, which were proposed and addressed. In addition, the review winds up with a brief deliberation for more exploration into air purification photocatalysis.


Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , Contaminantes Ambientales , Compuestos Orgánicos Volátiles , Contaminación del Aire/prevención & control , Catálisis , Gases , Humanos , Metales , Titanio
14.
Environ Res ; 214(Pt 3): 113953, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-35934147

RESUMEN

A popular approach to select optimal adsorbents is to perform parallel experiments on adsorbents based on an initially decided goal such as specified product purity, efficiency, or binding capacity. To screen optimal adsorbents, we focused on the max adsorption capacity of the candidates at equilibrium in this work because the adsorption capacity of each adsorbent is strongly dependent on certain conditions. A data-driven machine learning tool for predicting the max adsorption capacity (Qm) of 19 pharmaceutical compounds on 88 biochars was developed. The range of values of Qm (mean 48.29 mg/g) was remarkably large, with a high number of outliers and large variability. Modified biochars enhanced the Qm and surface area values compared with the original biochar, with a statistically significant difference (Chi-square value = 7.21-18.25, P < 0.005). K- nearest neighbors (KNN) was found to be the most optimal algorithm with a root mean square error (RMSE) of 23.48 followed by random forest and Cubist with RMSE of 26.91 and 29.56, respectively, whereas linear regression and regularization were the worst algorithms. KNN model achieved R2 of 0.92 and RMSE of 16.62 for the testing data. A web app was developed to facilitate the use of the KNN model, providing a reliable solution for saving time and money in unnecessary lab-scale adsorption experiments while selecting appropriate biochars for pharmaceutical adsorption.


Asunto(s)
Contaminantes Químicos del Agua , Agua , Adsorción , Carbón Orgánico , Aprendizaje Automático , Preparaciones Farmacéuticas , Contaminantes Químicos del Agua/análisis
15.
Molecules ; 27(6)2022 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-35335388

RESUMEN

In recent years, conjugated microporous polymers (CMPs) have become important precursors for environmental and energy applications, compared with inorganic electrode materials, due to their ease of preparation, facile charge storage process, π-conjugated structures, relatively high thermal and chemical stability, abundance in nature, and high surface areas. Therefore, in this study, we designed and prepared new benzobisthiadiazole (BBT)-linked CMPs (BBT-CMPs) using a simple Sonogashira couplings reaction by reaction of 4,8-dibromobenzo(1,2-c;4,5-c')bis(1,2,5)thiadiazole (BBT-Br2) with ethynyl derivatives of triphenylamine (TPA-T), pyrene (Py-T), and tetraphenylethene (TPE-T), respectively, to afford TPA-BBT-CMP, Py-BBT-CMP, and TPE-BBT-CMP. The chemical structure and properties of BBT-CMPs such as surface areas, pore size, surface morphologies, and thermal stability using different measurements were discussed in detail. Among the studied BBT-CMPs, we revealed that TPE-BBT-CMP displayed high degradation temperature, up to 340 °C, with high char yield and regular, aggregated sphere based on thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. Furthermore, the Py-BBT-CMP as organic electrode showed an outstanding specific capacitance of 228 F g-1 and superior capacitance stability of 93.2% (over 2000 cycles). Based on theoretical results, an important role of BBT-CMPs, due to their electronic structure, was revealed to be enhancing the charge storage. Furthermore, all three CMP polymers featured a high conjugation system, leading to improved electron conduction and small bandgaps.


Asunto(s)
Polímeros , Pirenos , Electrodos , Electrones , Polímeros/química
16.
Chemistry ; 26(45): 10283-10289, 2020 Aug 12.
Artículo en Inglés | MEDLINE | ID: mdl-32281180

RESUMEN

Recently, miniaturized power supplies have become essential components of micro-electromechanical systems (MEMS) and portable microdevices due to their high-power density, moderate specific energy, and superior long-term cyclability. In this study, microsupercapacitors with ZIF-8-derived carbons as active materials were successfully fabricate by electrophoretic deposition method. The carbon materials on microsupercapacitors, which are directly deposited or obtained by pyrolyzing predeposited ZIF-8 particles, play a crucial role in achieving outstanding electrochemical performances. The microsupercapacitor of 16 interdigital finger electrodes, prepared by electrophoretic deposition of ZIF-8 particles and subsequent pyrolysis, shows maximum specific power 687.6 mW cm-3 , specific energy 2.87 mWh cm-3 , and 97.8 % capacitance retention rate after 10 000 cycles. The simple and facile process of electrophoretic deposition and subsequent pyrolysis of ZIF-8 particles generates a film of densely populated microporous carbon particles on microsupercapacitor, leading to superior capacitive performances.

17.
Environ Res ; 190: 109976, 2020 11.
Artículo en Inglés | MEDLINE | ID: mdl-32750555

RESUMEN

Fast pyrolysis of lignin can obtain valuable products such as bio-oil, bio-chemical, syngas, and biochar. In this study, two types of lignin known as brown solid from the byproduct of cellulosic ethanol fermentation and commercial dealkaline lignin from the papermaking process were used for pyrolysis in a 3-L batch reactor at 300-450 °C. The product composition in the liquid and gas phases were analyzed by using gas chromatography-mass spectrometry/Flame-ionization detector/thermal conductivity detector (GC-MS/FID/TCD). Increasing the N2 flow rate to 150 mL/min was sufficient to increase the production of bio-oil/bio-organics up to 15% for brown solid pyrolysis. In contrast, the biochemical production during dealkaline lignin pyrolysis was not sensitive to the change of the N2 flow rate. The amount of biochar produced in the pyrolysis (~60%) slightly changed at various pyrolysis temperature and gas flow rate, which could be due to the relatively low pyrolysis temperature that was insufficient to decompose the lignin. The GC-MS analysis also revealed that C7-C8 compounds, which represented the phenolic compounds, were the most abundant in the liquid products. Kinetic models of the pyrolysis were established based on the thermogravimetric analysis.


Asunto(s)
Lignina , Pirólisis , Biocombustibles , Cromatografía de Gases y Espectrometría de Masas , Calor , Fenoles , Temperatura
18.
Environ Res ; 191: 110176, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32950515

RESUMEN

To minimize waste production and reduce reliance on fossil fuels, agricultural waste such as rice straw has been actively used in biochemical production. In Taiwan, cellulosic waste has been used in anaerobic digestion for bioethanol production. This process produces a large amount of biomass-associated sludge that may become a serious environmental issue. Therefore, in this study, the anaerobic digestion sludge was recycled for the production of activated carbon via pyrolysis and activation by KOH. Surface characterization showed increased surface area and development of microporous structure upon activation. The FTIR image showed that high temperature activation eliminated most functional groups in the activated carbon, except for CO and C-O groups. The results showed that the activated carbon could be used for pollutant adsorbents such as molecular dyes (methylene blue: 217 mg g-1) and metal ions (copper: 169 mg g-1) from aqueous solution. In addition, the as-synthesized activated carbon can be used for CO2 capture and capacitor. Instead of focusing on one single application, we proposed that centralized production of activated carbon could be used in various applications, while further modification could be adopted depending on the need of its specific application.


Asunto(s)
Carbón Orgánico , Aguas del Alcantarillado , Biomasa , Reciclaje , Taiwán
19.
Chemistry ; 24(23): 6127-6132, 2018 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-29624740

RESUMEN

Mesoporous carbon can be synthesized with good control of surface area, pore-size distribution, and porous architecture. Although the relationship between porosity and supercapacitor performance is well known, there are no thorough reports that compare the performance of numerous types of carbon samples side by side. In this manuscript, we describe the performance of 13 porous carbon samples in supercapacitor devices. We suggest that there is a "critical pore size" at which guest molecules can pass through the pores effectively. In this context, the specific surface area (SSA) and pore-size distribution (PSD) are used to show the point at which the pore size crosses the threshold of critical size. These measurements provide a guide for the development of new kinds of carbon materials for supercapacitor devices.

20.
Chemistry ; 23(1): 51-56, 2017 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-27906482

RESUMEN

Despite the great success of controlled synthesis of metal nanocrystals with various sizes and morphologies, an efficient one-pot approach to preparing well-organized three-dimensional (3D) structures with unique facets exposed remains a great challenge. Herein, we report a unique 3D nanoarchitecture for PdCu alloy, created by a simple chemical reduction method, in which nanosized octahedral PdCu nanocrystals are directly assembled into 3D super-branched structures. Detailed investigations of its electrocatalytic performance demonstrate that the as-prepared facet-controlled PdCu super-branched nanostructures possess higher activity towards the formic acid oxidation reaction in comparison to the commercially available Pd black catalyst.

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