One-step Microwave Method Research Articles

Exploration and Design of Carbon Dot-Based Long Afterglow Materials Using Active Machine Learning and Quantum Chemical Simulations.

Long afterglow materials based on carbon dots (CDs) have attracted extensive attention in the field of optics due to their low cost and nontoxic properties. However, the targeted synthesis of specific properties of complex and unknown structures such as CDs remains a daunting challenge. In this study, the powerful nonlinear fitting ability of machine learning was used to explore the afterglow properties of CDs. The XGBoost algorithm demonstrates high prediction accuracy in determining the optimal excitation wavelength, optimal emission wavelength, and afterglow lifetime. Using Bayesian optimization, we screened and synthesized the CDs-based long afterglow materials with the longest lifetime reported so far by a one-step microwave method. By combining quantum chemical calculations with experimental data, we revealed the structure-function relationship between CDs and their precursors through electron-hole analysis. These results show that machine learning can establish nonlinear correlations between precursors and materials with unknown structures, clarify their intrinsic relationships, simplify the material design process, and thus accelerate the development of advanced materials.

Selective detection of Co2+ by L-CyS/AA CQDs and Construction of PASS 0 gate

Since the accidental discovery of carbon quantum dots (CQDs) in 2004, they have been widely used in the field of fluorescence sensing by combining their good optical and physicochemical properties with a wide source of raw materials and a simple synthesis process. In this work, we have synthesised sulphur-doped carbon quantum dots L-CyS/AA CQDs by a one-step microwave method using L-cysteine (L-CyS) and ascorbic acid (AA) as carbon and sulphur sources. It was also analysed by fluorescence spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The prepared L-CyS/AA CQDs showed good dispersion under TEM with a spherical shape and an average particle size of 7.3 nm. L-CyS/AA CQDs were observed to be bright blue-green fluorescent with strong fluorescence (>3.5*103 a.u.) under UV light irradiation. PASS 0 logic gate operation can be achieved by controlling different fluorescent input and output. L-CyS/AA CQDs were able to achieve selective detection of Co2+ with a LOD of 63.2 μM, which provides a new method for Co2+ detection that can be used for the detection of Co2+ in real water samples.

Microwave-assisted fast preparation of functionalized carbon dots: The impact of ionic liquid precursor on corrosion inhibition

In this study, functionalized carbon dots were synthesized in one step from L-histidine and imidazolyl ionic liquids using an ionic liquid-assisted microwave method as green corrosion inhibitors for steel in a 1 M HCl solution. Different ionic liquid anions (CF3COO- and HSO4-) were introduced in the preparation of the carbon dots, and their microstructures and surface properties were characterized. Notably, the corrosion inhibition efficiency of the prepared CDs (assisted by CF3COO-) reached 94.2% at 5 mg‧dm−3. The corrosion inhibition behavior of CDs on mild steel in 1 M HCl was investigated through DFT calculations. Our investigation revealed that the anions of the selected ionic liquids have a certain influence on the structure of the carbon dots, which correlates with the performance of the carbon dot corrosion inhibitor. Therefore, this study provides guidance for the preparation of functionalized carbon dot corrosion inhibitors using a one-step microwave method and the selection of ionic liquids (as solvents, modifiers, and mediums for microwave conversion).

Multifunctional antibacterial enhanced amoxicillin carbon nanodots for the detection of Hg (II) and methanol in edible alcohol

Amoxicillin was used as the sole precursor to rapidly synthesize amoxicillin carbon nanodots via a one-step microwave method. The diameter of the amoxicillin carbon nanodots was concentrated at 1.8 ± 0.6 nm, with fluorescence excitation-dependent characteristics. After characterization, the carbon nanodots retained some of the amoxicillin structure, exhibiting low biological toxicity and good antibacterial activity. Due to the formation of the carbon dots structure, the hydrophilicity and water solubility of the amoxicillin carbon nanodots improved. An antibacterial plate experiment further showed that the antibacterial performance of the amoxicillin carbon nanodots was higher than that of the original amoxicillin. The amoxicillin carbon nanodots could quickly and conveniently detect Hg2+ via changes in their fluorescence intensity. Moreover, several aliphatic alcohols could be distinguished and quantified based on the fluorescence intensity increase of the amoxicillin carbon nanodots. Most importantly, the amoxicillin carbon nanodots quickly identified and quantified methanol mixed in edible alcohol. These multifunctional amoxicillin carbon nanodots have broad application prospects in antibiosis, toxic Hg2+ detection, and identification and detection of several aliphatic alcohols, especially the microfluorometric determination of methanol in edible alcoholic beverages.

Rapid Quantitative Detection for Nitrofurantoin Based on Nitrogen-Doped Highly Photoluminescent Carbon Dots.

Nitrogen-doped carbon dots (NCD) with high fluorescence retention and good stability were successfully fabricated using citric acid and urea via a facile and eco-friendly one-step microwave method, which exhibited superior specificity for detection of nitrofurantoin (NFT). Upon the addition of NFT, the fluorescence intensity of NCD at 450 nm was significantly decreased. Besides, a satisfactory linear relationship between the fluorescence quenching efficiency and concentrations of NFT was obtained. Especially, NCD was qualitatively and quantitatively applied for detection NFT in milk and meat extract samples with a high recovery rate. Consequently, it was suggested that the detection method had potential application in the specific detection of NFT, offering a novel approach for veterinary drug residue detection.

Composites of Bi2Se3 nanoparticles and FeSe2 nanoparticles for supercapacitor anode materials

The low capacity of negative electrode materials for supercapacitors limits their practical applications. In this study, the bimetallic selenides Bi2Se3/FeSe2 were efficiently prepared by a convenient one-step microwave method. The attributes of nanoparticles such as surface morphology, crystal structure, elemental valence, and distribution regions were verified by a series of characterization tools. The composite electrode exhibits high electrochemical performance in the 1.2 V negative potential window. The capacitance of the Bi2Se3/FeSe2 electrode is 274 mAh g−1 at 1 A g−1. These results indicate that Bi2Se3/FeSe2 holds great potential for supercapacitor anode materials. In particular, the asymmetric water-based supercapacitor dual-electrode device (NiSe/NiTe2//Bi2Se3/FeSe2) shows an impressive power/energy density of 56.25 Wh kg−1 at 774.67 W kg−1. The capacitance of ASC is reduced by 20.10 % and the coulomb efficiency is maintained at 99.45 % over 3000 cycles.

Facile synthesis of an α-Bi2O3/BiO2 heterojunction for enhanced piezoelectric catalytic degradation of dye wastewater

This study employed a one-step microwave method to fabricate an α-Bi2O3/BiO2 heterojunction with a narrow bandgap which exhibited a high efficiency in the degradation of methyl orange dye.

Transforming human hair fibers into carbon dots: Utilization in flexible films, fingerprint detection, counterfeit prevention and Fe3+ detection

Creating environmentally-friendly fluorescent carbon quantum dots (HCQDs) from human hair is a straightforward process with versatile applications. These HCQDs, derived from non-toxic hair, are produced through a one-step microwave (MW) method and have gained increasing attention due to their exceptional properties. Despite the availability of various advanced HCQDs, their full potential remains untapped. Thanks to their remarkable optical characteristics, HCQDs serve as highly sensitive nano-probe agents for the fluorometric measurement of Fe3+ ions. The fluorescence (FL) intensity of the nano-probe exhibits a linear correlation with Fe3+ ion concentration ranging from 0 to 50 μM, boasting a limit of detection (LoD) of approximately 0.13 μM. This sensitivity is achieved through resonance energy/electron transfer-induced FL quenching. Remarkably, carbon dots (CDs) obtained from human hair function as ink-free patterned substrates, making them ideal for printing and the nondestructive collection and detection of latent fingerprints (LFPs). Immersing LFPs in HCQDs@poly(vinyl alcohol) (HCQDs@PVA) solution yields flexible, transparent films with consistent luminescent LFPs and clear ridge features for accurate personal identification. Importantly, this technique allows for the lifting and identification of long-term exposed LFPs from various surfaces without causing any damage. The segregation of HCQDs within the polymer matrix during film formation is the mechanism responsible for LFP collection and visualization. Overall, HCQDs@PVA composites exhibit outstanding performance, suitable for applications in fluorescent patterns, flat panel displays, LFP analysis, and anti-counterfeiting (AC) labeling.

Novel polysaccharide-derived carbon dots doped with N, S, P: Synthesis, characterization, in vitro antioxidant, fluorescence sensor for chromium (VI) detection and cellular imaging

In this work, for the first time, biomass-derived carbon dots (AMP-CDs) with strong water solubility, antioxidant activity and good biocompatibility were synthesized by a one-step microwave method using Allium macrostemon Bunge polysaccharides (AMP) as the main carbon source, L-cysteine as the nitrogen and sulfur source, and phosphoric acid as the phosphorus source. The results showed that sphere-like AMP-CDs with an average particle size of about 2.34 ± 0.49 nm were successfully prepared, with good resistance to salt and photobleaching, and maintained high fluorescence intensity under normal pH conditions in human body. AMP-CDs were highly resistant to 2,2-diphenyl-1-pycrylhydrazyl (DPPH), 2,2′-Azinobis- (3-ethylbenzthiazoline-6-sulphonate) (ABTS) and hydroxyl radical (·OH) with significantly higher scavenging ability than AMP, with IC50 (μg/mL) of 10.240, 7.265, and 574.730, respectively. In addition, AMP-CDs can be selectively used for the sensitive detection of Cr6+ with the limit of detection was 5.25 μM, and satisfactory results were obtained for the Cr6+ recovery experiments of actual environmental samples. In vitro cytotoxicity and hemolytic activity assays showed that AMP-CDs have good biocompatibility and can smoothly enter cells for clear imaging. Therefore, AMP-CDs are likely expected to be applied as a potential antioxidant and metal ion detection probe in the field of drug and food, environmental and biological scenario samples for metal ion detection analysis.

One-step microwave synthesis of FeSe2@CNT as high-performance supercapacitor anode material

In this work, FeSe2@CNT nanocomposite anode materials are fabricated using a convenient and efficient one-step microwave method. The FeSe2@CNT electrode exhibits superior electrochemical performance. The carbon nanotube structure effectively mitigates the severe volume change in the FeSe2@CNT electrode during continuous charge and discharge. Thus, the capacitance value of 573 F g−1 and capacitance retention of 81.9% for 3000 constant current charge and discharge cycles are achieved. In addition, the asymmetric device assembled with FeSe2@CNT as the anode and NiSe2@CNT as the cathode exhibits high Energy density (E can reach 41.32 Wh kg−1 when P is 800 W kg−1), and the device achieves 82.6% capacity retention after 3000 cycles.

Cefminox sodium carbon nanodots for treatment and bacterial detection of bloodstream infection

Cefminox sodium carbon nanodots were synthesized via a rapid one-step microwave method using cefminox sodium as sole precursor. The prepared cefminox sodium carbon nanodots had good water solubility and the diameter was concentrated at 1.29 ± 0.40 nm with relative uniform. They exhibited fluorescence excitation-dependent property, of which optimal excitation wavelength was ∼ 390 nm, and optimal emission wavelength was ∼ 465 nm. As retained part of the structure and antibacterial properties of cefminox sodium, cefminox sodium carbon nanodots had low biological toxicity and sufficient antibacterial activity against bacteria in vitro. In vivo experiments demonstrated cefminox sodium carbon nanodots could exert a good therapeutic effect on acute bloodstream infection. In the mixed solution (Escherichia coli, blood and cefminox sodium carbon nanodots), the fluorescent intensity exhibited quadratic functional relationship with the concentration of Escherichia coli. The detection concentration range for Escherichia coli was 0.5 × 106 ∼ 1 × 109 CFU/mL, and the detection limit was 3.7 × 105 CFU/mL. It suggested cefminox sodium carbon nanodots can rapidly and quantitatively detect the number of Escherichia coli in blood while effectively treating bloodstream infection. Due to the long period of clinical detection time (about 1–5 days or more) for bacterial counts in the blood of patients, this method provides a new strategy for rapid clinical treatment and effective monitoring of the degree of infection in patients.

Withania somnifera-derived carbon dots protect human epidermal cells against UVB-induced cell death and support growth factor-mediated wound healing.

Solar radiation comprising UVA and UVB regions is considered a skin-damaging factor inducing inflammation, oxidative stress, hyperpigmentation, and photo-aging. Photoluminescent carbon dots (CDs) were synthesized from the root extract of a Withania somnifera (L.) Dunal plant and urea, using a one-step microwave method. These Withania somnifera CDs (wsCDs) were 14.4 ± 0.18 d nm in diameter and presented photoluminescence. UV absorbance showed the presence of π-π* (C[double bond, length as m-dash]C) and n-π* (C[double bond, length as m-dash]O) transition regions in wsCDs. FTIR analysis indicated the presence of nitrogen and carboxylic functional groups on the surface of wsCDs. HPLC analysis of wsCDs showed the presence of withanoside IV, withanoside V, and withanolide A. The wsCDs were found to be biocompatible in human skin epidermal (A431) cells and hindered UVB irradiation-induced loss of metabolic activity and oxidative stress. The wsCDs supported rapid dermal wound healing through augmented TGF-β1 and EGF gene expression levels in A431 cells. Finally, wsCDs were found to be biodegradable through a myeloperoxidase-catalyzed peroxidation reaction. The study concluded that under in vitro conditions, Withania somnifera root extract-derived biocompatible carbon dots provided photo-protection against UVB-stimulated epidermal cell damage and supported rapid wound healing.

One-step microwave method realizes two-step strategy to enhance the photocatalytic performance of fly ash: Enhance the carrier transfer efficiency and inhibit the carrier recombination

To address the negative impacts of fly ash (FA), its potential applications in various fields, including photocatalysis, should be investigated. In this study, a photocatalyst (P–C-dots@FA/P–C) with phosphorized carbon-dots (C-dots) and carbon layer on FA was synthesized by a one-step microwave method. To obtain the optimal catalytic activity, the synthesis conditions of different phosphoric acid contents and microwave times were tested. The addition of 18% phosphoric acid yielded the highest catalytic activity under a microwave of 700 W for 4 min. In addition, the photocatalytic activity of P–C-dots@FA/P–C for Rhodamine B was 238 times higher than that of FA alone. Furthermore, the doping of phosphorus resulted in the formation of C-dots on the FA surface, thereby obtaining the P–C-dots@FA material with an enhanced photocatalytic activity of P–C. This material enhanced the transfer of photogenerated carriers, was further carbonized to form a carbon layer, and weakened the recombination of photogenerated carriers. The stability experiment of the material proves that the material has good reproducibility, stability, and recyclability.

One-step microwave synthesis of in situ grown NiTe nanosheets for solid-state asymmetric supercapacitors and oxygen evolution reaction

In this work, self-supported NiTe nanosheets were prepared via one-step microwave method. XRD and XPS spectroscopy showed the successful synthesis of NiTe material in the hexagonal crystal system. SEM and EDS were used to identify the microscopic morphology and composition of NiTe on nickel foam (NF). The electrode demonstrated specific capacitance (Cs) of 808.9 F g −1 and ultra-long cycle life of 60,000 cycles. In addition, a solid-state asymmetric supercapacitor consisted of NiTe@NF electrode as cathode material and demonstrated the largest energy density and power density of 94.4 μWh cm −2 and 7801.8 μW cm −2 , respectively, and the specific capacitance remained 83.3% after 20,000 cycles. Moreover, the as-obtained NiTe@NF catalyst also displayed an excellent catalytic activity for oxygen evolution reaction (OER), which achieved an ultra-low overpotential of 199.5 mV at 10 mA cm −2 . • The NiTe nanosheet offered outstanding specific capacitance of 808.9 F g −1 . • Superior durability of 91.4% retention during 60,000 cycles. • The NiTe@NF electrode delivered a small Tafel slope and a low overpotential. • Self-supporting NiTe nanosheets were prepared within 150 s via a microwave method.

One-step microwave method synthesis of Fe3O4 nanoribbon@ carbon composite for Cr (Ⅵ) removal

Cr(VI) is recognized as a non-biodegradable and toxic pollutant, resulting from manufacturing and industrialization processes, which can trigger considerable environmental problems. Herein, a novel nitrogen, sulfur co-doped carbon with Fe3O4 nanoribbons composite was synthesized by microwave method within 150 s and applied for Cr(Ⅵ) removal. The raw materials are ferrous sulfate heptahydrate, thiourea and glycerin. Among them, thiourea is served as the rich precursor of carbon nitrogen and sulfur elements and can be used to prepare carbon materials co-doped with N and S elements, while ferrous sulfate heptahydrate can provide iron element for catalyzing rapid preparation of carbon-based materials and self-generation of Fe3O4 nanoribbons. Glycerol not only can be used as a solvent but also can efficiently absorb microwave radiation to make the original quickly heated. The result shows that the addition of Fe3O4 nanoribbons would greatly improve the removal of hexavalent chromium. Meanwhile, the adsorption characteristics were investigated by analyzing by the effects of pH, adsorption kinetics and adsorption isotherms. The result indicates that Fe3O4 nanoribbons can be successfully loaded onto the carbon materials. The maximum adsorption capacity of synthesized material (nitrogen and sulfur co-modified carbon/Fe3O4 (N,S-C/Fe3O4-1) composite) for Cr(Ⅵ) can be reached at pH = 5, probably due to the protonation of functional groups. The adsorption process follows the pseudo-second-order kinetics with the maximum adsorption capacity of 134 mg/g according to Langmuir isotherm model, manifesting that the Cr(Ⅵ) adsorption process is close to monolayer chemisorption. In this work, a new nitrogen and sulfur co-doped carbon/Fe3O4 composite with high Cr(Ⅵ) removal capacity can be successfully prepared within three minutes.

Green synthesis of mango ginger (Curcuma amada) derived fluorescent carbon dots—a potent label-free probe for hexavalent chromium sensing in water

Carbon dots from bio-resources recently received significant impact due to ease of availability, low cost, and simple equipment requirements. In this work, a highly fluorescent carbon dots derived from agro-bio-based precursor, mango ginger rhizomes were developed through a straightforward, low-cost, rapid, economical, and one-step microwave method, without using any chemical reagents or any expensive instruments. The prepared carbon dots exhibited excitation-dependent fluorescence with excitation and emission maxima at 360 and 442 nm, respectively. On account of the excellent photoluminescent property of the system prepared, it is executed as an outstanding hexavalent chromium sensor by fluorescence quenching. Extensive usages of this metal in different fields are unfavorable and cause pollution to the ecological system, and thus sensing of hexavalent chromium in an environmental sample, especially in water resources are highly demandable. The system possesses higher selectivity and sensitivity toward chromium with a limit of detection of 84 nM (4.367 ppb) and a linear relationship between the concentration of chromium and fluorescence intensity maintained from 0 to 33.33 µM. The mechanism was studied using different methods and finally attributed to the inner filter effect. Hereby value addition has been given to the agro-based precursor through an environmentally benign method and is successfully employed as a hexavalent chromium sensor in real water samples with recovery from 95.07 to 102.70%.

Microwave-based preparation of γ-Fe2O3/SrTiO3 photocatalyst for efficient degradation of organic pollutants in water

Photocatalysis is considered one of the most promising wastewater treatment technologies. In this work, a magnetic photocatalytic γ-Fe2O3/SrTiO3 composite with high performance and stability were synthesized by a one-step microwave method, and the amount of γ-Fe2O3 on methylene blue (MB) and tetracycline (TC) degradation performance of composite photocatalyst was investigated under simulated sunlightand. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible diffuse reflectance spectra (UV–vis DRS) and electron spin resonance (ESR). The degradation of MB and TC over 0.3% γ-Fe2O3/SrTiO3 was found to be very effective, and the degradation reached 84.91% (150 min) and 92.03% (60 min), respectively. After five consecutive cycles of reusability test under visible light irradiation, the photocatalytic degradation efficiency remained unchanged. According to the results of free radicals capture experiments and ESR, superoxide radical and hole were found to be the main active species for MB degradation. The degradation products were identified by liquid chromatography triple quadrupole mass spectrometry (LC-MS), and a possible degradation pathway of TC was proposed. Thus, magnetic composites provide a new strategy for the design of photocatalysts with excellent catalytic performance, which is conducive to recovery.

High-efficiency one-step microwave method for high-performance biomass-based hierarchical porous carbon

High-efficiency one-step microwave method for high-performance biomass-based hierarchical porous carbon

Reduced-graphene-oxide-modified self-supported NiSe2 nanospheres on nickel foam as a battery-type electrode material for high-efficiency supercapacitors

Self-supported NiSe2 nanospheres have been successfully synthesized by a one-step microwave method, and then coated with a layer of reduced graphene oxide (rGO) by a simple dip-coating method. Due to the excellent conductivity and high surface area of rGO, as a battery-type electrode material, the as-prepared NiSe2@rGO composite exhibited an excellent specific capacity of 224.75 mAh g−1 at 1 A g−1, far exceeding that of the NiSe2 nanospheres (72.5 mAh g−1 at 1 A g−1). NiSe2@rGO showed good cycling performance, with 78.13% retention of its initial capacity after 5000 cycles. Furthermore, an NiSe2@rGO//activated carbon (AC) asymmetric supercapacitor (ASC) showed a high energy density (E) of 25.85 Wh kg−1 at a power density (P) of 730 W kg−1. The NiSe2@rGO//AC showed good capacity retention, maintaining 85.45% of the original value after 10000 cycles.

Tunable full-color solid-state fluorescent carbon dots for light emitting diodes

Carbon dots (CDs) as a class of new fluorescent materials have attracted numerous attention. However, the solid-state photoluminescence quenching of CDs is still a big challenge. In this work, self-quenching-resistant solid-state fluorescent CDs are achieved, which exhibit tunable full-color solid-state emission without any other additional solid matrices. These CDs were prepared via one-step microwave method using phloroglucinol and urea as sources by regulating reactant ratio and microwave power. The maximum emission of CDs gradually shifts from 445 to 643 nm, and solid-state quantum yield of five typical CDs with blue (B), green (G), yellow (Y), orange (O) and red (R) emission reaches up 48.2%, 26.0%, 18.5%, 13.7% and 5.7%, respectively. Moreover, multicolor solid-solid fluorescence mechanism of CDs is investigated. The G-, Y-, O-, R-CDs show aggregation-induced red-shift behavior, while B-CDs exhibit unique crystallization-induced emission enhancement property. Finally, CDs are utilized as phosphors combing with ultraviolet chip to fabricate multicolor and white light emitting diodes (LEDs). The obtained white LEDs exhibit an adjustable correlated color temperature (3937–8588 K) and high color rendering index (80–88). This study provides a novel guidance for developing self-quenching resistant CDs with multicolor emission.