Hydrothermal Synthetic Method Research Articles

Facile Synthesis of Nd2Fe14B Hard Magnetic Particles with Microwave-Assisted Hydrothermal Method

The synthesis of Nd-Fe-B magnetic powders via chemical techniques presents significant promise, but poses challenges due to their inherent chemical instability. In this investigation, Nd-Fe-B hard magnetic particles were synthesized utilizing an eco-friendly and simple microwave-assisted hydrothermal synthetic method. The technique involves the synthesis of the Nd-Fe-B oxide precursor using the microwave-assisted hydrothermal method, followed by reduction–diffusion using CaH2. The microwave-assisted hydrothermal technique presents a viable approach for preparing Nd-Fe-B precursor particles, offering advantages such as time and energy efficiency and environmental sustainability. The synthesized Nd-Fe-B particles demonstrated a coercivity of up to 2.3 kOe. These magnetic particles hold significant potential for use in high-performance permanent magnets, and can effectively contribute to developing high-energy density exchange-coupled nanocomposite magnets. This study also offers valuable insights into the design and synthesis of additional magnetic materials based on rare earth elements.

Edge-generated N-doped carbon-supported dual-metal active sites for enhancing electrochemical immunoassay

Development of high-precision human epidermal growth factor receptor 2 (HER2) assay is essential for the early diagnostic and prevention of breast cancer. In this work, an innovative Fe/Mn bimetallic nanozyme at the edge of N-doped carbon defects (FeMn-NCedge) with abundant active sites was prepared through the hydrothermal synthetic method. FeMn-NCedge nanozyme displayed excellent peroxidase-like activity relative to the H2O2-catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) system for generation of the oxidized TMB (oxTMB). As a proof-of-concept application, we constructed an electrochemical immunoassay for the detection of HER2 based on the unique merits of FeMn-NCedge. Initially, a sandwiched immunoreaction was carried out in the microtiter plate coated with monoclonal anti-HER2 capture antibodies using glucose oxidase (GOx)-labeled anti-HER2 as detection antibody. The carried GOx could catalyze glucose to produce H2O2, thus resulting in the formation of oxTMB with the assistance of TMB and FeMn-NCedge nanozyme. The produced oxTMB could be determined on the electrode by the chronoamperometry at an applied potential of +10 mV. Experimental results revealed that the steady-state current increased with the increasing HER2 concentration in the sample, and gave a good linear relationship within the dynamic range of 0.01–10 ng/mL at a limit of detection of 5.4 pg/mL HER2. In addition, good reproducibility, high specificity and acceptable accuracy were acquired for the measurement of human serum samples. Importantly, this method can be extended for quantitative monitoring other disease-related proteins by changing the corresponding antibodies.

High sensitivity and fast response sensor for formaldehyde based on In2O3/Sn2O3 heterojunction

Modifying metal oxide semiconductor materials is a primary approach to enhance gas sensor performance, and heterojunction is a promising method to address cross-sensitivity issues in gas sensors. Sn2O3 nanoflower-based substrates and In2O3/Sn2O3 heterojunction structures were successfully synthesized by hydrothermal synthetic method. The gas-sensing performance of the In2O3/Sn2O3 heterojunction-based gas sensor towards formaldehyde gas was investigated. The gas sensor based on In2O3/Sn2O3 heterojunction exhibited higher sensitivity to formaldehyde gas compared to pure Sn2O3 gas sensor at the same operating temperature. The response and recovery rates of the sensor were significantly improved as well. In addition, the In2O3/Sn2O3 gas sensor exhibited lower response to interfering gases compared to its response to formaldehyde gas, thus demonstrating superior selectivity over the pure Sn2O3 sensor. The result provides a research direction for the development of high-performance, highly selective, and rapid response formaldehyde sensors, which has certain reference significance for the advancement of gas sensor technology.

Synthesis and anti-HIV-1 activity evaluation of Keggin-type polyoxometalates with amino acid as organic cations

Polyoxometalates (POMs), as a class of multinuclear metal oxygen clusters, have promising biological activities. And their amino acid derivatives will lead to better pharmacological activity by the diversity in structures and properties. With reference to the anti-HIV-1 activities of PM-19 (K7PTi2W10O40) and its pyridinium derivatives, a series of novel Keggin-type POMs with amino acid as organic cations (A7PTi2W10O40) were synthesized by hydrothermal synthetic method. The final products were characterized by 1H NMR, Elemental analyzes and single crystal X-ray diffraction. All the synthesized compounds were obtained in the yields of 44.3–61.7% and evaluated the cytotoxicity and anti-HIV-1 activity in vitro. Compared with the reference compound PM-19, the target compounds had a lower toxicity to TZM-bl cells and a higher inhibitory activity against HIV-1. Among them, compound A3 showed higher anti-HIV-1 activity with IC50 of 0.11 nM than that of PM-19 with 4.68 nM. This study demonstrated that combination of Keggin-type POMs and amino acids can be a new strategy to enhance the anti-HIV-1 biological activity of POMs. All results will be expected to helpful for developing more potent and effective HIV-1 inhibitors.

A new insight into the generation of hydrogen peroxide from carmine degradation by cryptomelane as a catalyst, oxidant, and adsorbent

Carmine, as a widely used dye, is one kind of refractory organic pollutants that endanger the water environment. Finding an efficient and environmentally friendly degradation method is a crucial step to treat dye-containing wastewater. Using a one-step hydrothermal synthetic method, cryptomelane was synthesized, characterized, and investigated for its ability to degrade carmine in an aqueous solution. Under the optimum conditions of a 2 g/L cryptomelane dosage and an initial pH of 6.8, 97.87% of 100 mg/L carmine degraded within 240 mins. Cryptomelane exhibited excellent reusability after three cycles, with a decolorization efficiency of 85.39%. Cryptomelane accommodated a board working pH range. The carmine was efficiently decolorized via an interaction of oxidation, catalysis, and adsorption of cryptomelane in a ratio of 46.85:47.11:3.90, respectively. The existence of oxygen vacancies on cryptomelane was responsible for H2O2 generation, and O2•- and 1O2 active species were involved in the carmine degradation by cryptomelane. A low reaction activation energy (Ea = 6.36 kJ/mol) caused efficient removal of carmine by cryptomelane at ambient temperature. These findings notably distinguish three roles of cryptomelane as an adsorbent, oxidant, and catalyst in a pollutant removal system, and prove that cryptomelane may have extensive and promising utilization on refractory organic wastewater treatment without the need to add extra oxidants.

Nano ZnO embedded poly (ethylene glycol) diacrylate cross-linked carboxymethyl tamarind kernel gum (CMTKG)/poly (sodium acrylate) composite hydrogels for oral delivery of ciprofloxacin drug and their antibacterial properties

In this research work, a novel hydrogel network based on carboxymethyl tamarind kernel gum/poly (sodium acrylate) was synthesized by using poly (ethylene glycol) diacrylate (PEGDA) as a cross-linker. Zinc Oxide nanoparticles (ZnO NPs) were prepared via the hydrothermal synthetic method and developed ZnO NPs embedded within CMTKG/Poly (sodium acrylate) hydrogel for the controlled release studies of ciprofloxacin drug. Various techniques such as FTIR, XRD, FESEM, and TEM were used to characterize the synthesized ZnO NPs, pure hydrogel, and hydrogel nanocomposites. Various parameters such as drug loading (DL %), drug entrapment (DE %), gel content, and porosity were estimated for all the synthesized hydrogel nanocomposites. The results of swelling and rheological studies of hydrogel nanocomposites concluded that the embedded ZnO NPs increased hydrogel's swelling and thermal stability. The water absorption data were analyzed using the Power and Schott model. The result concluded that the Schott function model fitted the dynamic swelling data. The antibacterial action of CMTKG-based hydrogel nanocomposites was studied using E. coli (gram-negative) bacteria with the help of the disc diffusion method. The result showed that the incorporation of ZnO NPs enhanced the antimicrobial action of ciprofloxacin-loaded CMTKG-based hydrogels. The kinetic modelling of drug release was done using Higuchi and Korsmeyer - Peppas model. The higher value of regression coefficient (R2) close to unity indicated that the mechanistic pathway of drug release from the hydrogels was more fitted in the Korsmeyer-Peppas model followed by Fickian diffusion.

A biocompatible NIR-II light-responsive nanoknife for permanent male sterilization.

Nanomaterial-mediated photothermal therapy (PTT) is a promising strategy for permanent male sterilization owing to its easy operation, rapid heating, minimal invasiveness, and high spatiotemporal controllability. However, the currently available PTT for male sterilization utilizes irradiation sources in the first near-infrared window (NIR-I), which may suffer from incomplete sterilization due to the insufficient penetration depth of NIR-I light. Herein, we developed a facile one-pot hydrothermal synthetic method of cysteine-coated copper sulfide (Cys-CuS) nanosheets for the second NIR window (NIR-II) PTT-mediated permanent male sterilization. In this method, Cys acted not only as a template but also as a sulfur resource in the formation of Cys-CuS nanosheets. The obtained Cys-CuS nanosheets possessed good photothermal properties and satisfied deep-tissue light response capacity under 1064 nm laser exposure. Given this, the permanent male sterilization in vivo was readily achieved by Cys-CuS nanosheets in a rapid manner (only 40 s). To the best of our knowledge, it is the first time that nanomaterial-mediated NIR-II PTT is applied for permanent male sterilization. We believe that the facilely prepared biocompatible Cys-CuS nanosheets can serve as a promising NIR-II light-responsive nanoknife to control the overpopulation of domestic pets and stray animals.

A simple and stable chemiluminescence resonance energy transfer system based on Ce(IV)-MOFs for detection of sulfite

Chemiluminescence (CL) is an effective way for designing sulfite (SO32-) sensors. However, the practical application of these sensors was hampered so far due to the poor selectivity or stability of the probes (e.g., KMnO4 and Ce4+). In this work, the Ce(IV)-MOF was fabricated through a simple and time-saving hydrothermal synthetic method. The special structure of Ce(IV)-MOF endowed it with high selectivity and stability in the CL reaction. Based on chemiluminescence resonance energy transfer (CRET) from the luminescent intermediate of the CL system to dyes (Nile blue, and rhodamine B), a simple, stable and sensitive CL sensing platform for SO32- was successfully established. The proposed CL sensing platform with the outstanding CL efficiency hold great potential for detecting SO32- in complex samples. This study not only broadened the application of MOF in CL field, but also provided a new clue for the design of stable CL system and CRET process.

The degradation of printing and dyeing wastewater by manganese-based catalysts

Printing and dyeing wastewater generally has high pH, high turbidity, poor biodegradability, complex composition, and high chroma, which make it one of the most difficult industrial wastewaters to treat. Herein, heterogeneous ozone oxidation technology is applied to oxidize and degrade printing and dyeing wastewater. A metal oxide catalyst supported on activated carbon (γ-MnO2/AC) was prepared by hydrothermal synthetic method and shown to enable synergistic catalysis involving MnO2 metal sites and N/C sites. A simulated methyl orange solution was used to determine the effects of various preparation and operation parameters. The results confirmed that the γ-MnO2/AC catalyst exhibited good chemical oxygen demand (COD) removal and reusability. Additionally, γ-MnO2/AC demonstrated excellent degradation of the secondary biochemical effluent of printing and dyeing wastewater (COD removal = 72.45% within 120 min). The γ-MnO2/AC catalyst was fully characterized, and the mechanism governing its catalytic ozone oxidation process was investigated experimentally.

CeO2 modified Ni-MOF as an efficient catalyst for electrocatalytic urea oxidation

The development of cost-efficient electrocatalysts for urea oxidation reaction (UOR) is a challenge due to the slow kinetics. In this work, we demonstrated a one-pot hydrothermal synthetic method to fabricate CeO2 modified Ni-MOF nanosheets. When evaluted as UOR catalysts, the 3% CeO2/Ni-MOF possesses outstanding catalytic activity, achieving a current density of 10 mA cm−2 at a low potential of 1.356 V with a small Tafel slope of 13.83 mV dec−1. It is considered that the unique interactions between CeO2 nanoparticles (NPs) and Ni-MOF nanosheets (NSs) play the significant role in the enhancement of the catalytic performance by inducing the formation of abundant defects and optimized surface states.

Porous Lanthanide Metal-Organic Frameworks Using Pyridine-2,4-dicarboxylic Acid as a Linker: Structure, Gas Adsorption, and Luminescence Studies.

Two types of new lanthanide coordination networks, [Ln3(pdc)4(Hpdc)(H2O)3]·8H2O [H2pdc = pyridine-2,4-dicarboxylic acid; Ln = Ce (1), Pr (2), Sm (3), Eu (4); type A) and [Tb5(pdc)4(Hpdc)]·3H2O (type B), have been synthesized using a hydrothermal synthetic method. The former type A compound has an unfamiliar architecture, even basically comprised of primitive cubic (pcu) topology, and demonstrate porous gas adsorption behavior, giving several hundreds of square meters per gram surface areas after evacuation of the water molecules, while the latter type B compound does not show any porous properties. Most interestingly, the solvothermal synthetic method using N,N-dimethylformamide (DMF) as a solvent gives compounds that crystallize in a structure analogous to that of type A for Ln = La-Ho, probably formulated as [Ln3(pdc)4(Hpdc)·(DMF)m]·nDMF. These compounds also exhibit large surface areas after evacuation of the DMF molecules and also moderate amounts of hydrogen gas uptake at 77 K. The luminescence properties were investigated for Eu and Tb analogues at elevated temperatures, at which an unusual increase in the emission intensity was observed upon the release of solvents, and discussed based on their porous structure.

Highly Soluble Fluorinated Polyimides Synthesized with Hydrothermal Process towards Sustainable Green Technology.

Polyimides, a widely used engineering plastic, require use of large amounts of toxic and hazardous organic solvents which threaten our daily lives, calling for new and easy synthetic methods for sustainable environmentally friendly development. In this paper, highly soluble fluorinated polyimides based on 4,4′-(hexafluoroisopropylidene) diphthalic anhydride were synthesized via hydrothermal process without using any toxic organic solvents and the advantages of the newly demonstrated synthetic methods are shown by comparative analysis performed with the two conventional synthetic methods using organic solvent: thermal and chemical imidization. Lower temperature is required (~200 °C) compared to thermal imidization and functional groups for high fusibility formed more easily compared to chemical imidization. According to the comparative analysis, hydrothermally synthesized PIs showed excellent solubility and maintained high thermal stability (>500 °C) and glass transition temperature (>300 °C) compared to conventional PI. The hydrothermally synthesized polyimide is much more convenient to store and manage than other form of polyimide which is much more stable when it is exposed to humidity as it is a powder form. The hydrothermal synthetic method is verified to be a “Green” and facile method for sustainable PI synthesis.

Fe3＋ coordinated to amino-functionalized spherical mesoporous silica: Preparation, characterization, and application as a rapid and efficient adsorbent for As(V) removal

A facile hydrothermal synthetic method was employed for the preparation of Fe 3＋ coordinated to amino-functionalized spherical mesoporous silica (Fe–NH 2 –SMS), aimed at the rapid and efficient removal of As(V) from water. The morphology, structure and properties of the adsorbent were characterized via SEM, EDS, N 2 adsorption–desorption, FT-IR, zeta-potential and XPS. Fe–NH 2 –SMS exhibited a high performance for As(V) removal with a very fast adsorption rate (reaching equilibrium within 1 min). As(V) adsorption on Fe–NH 2 –SMS was better fitted to the Langmuir isotherm model ( R 2 = 0 .988). The maximum adsorption capacity was 43.34 mg g –1 As(V) at 25 °C. The optimum pH for As(V) adsorption was in the range of 5–10. The individual presence of SO 4 2– , SO 3 2– , HPO 4 2– and CO 3 2– had a negative effect on As(V) adsorption. The removal of As(V) via Fe–NH 2 –SMS in real water samples remained above 95% with an increasing adsorbent dosage up to 1.6 g L –1 . Reusability studies indicated that the removal of As(V) was still up to 76% after five adsorption–desorption cycles. Electrostatic attraction and inner-sphere complexation between As(V) and functional groups (–NH 2 ⋅ ⋅ ⋅ Fe 3＋ ) were identified as the adsorption mechanisms of As(V). The prepared adsorbent can be considered a promising adsorbent for the rapid adsorption of As(V) from water. • Fe–NH 2 –SMS can reach the adsorption equilibrium within 1 min of contact time. • Fe–NH 2 –SMS showed wide pH applicability (5–10). • Fe–NH 2 –SMS exhibited the excellent As(V) removal of 99%. • As(V) removal of real water samples was satisfactory. • As(V) adsorption mechanism was electrostatic attraction and inner-sphere complexation.

Synthesis of highly luminescent carbon dots from postconsumer waste silk cloth and investigation of its electron transfer dynamics with methyl viologen dichloride

Synthesis of luminescent carbon dots (CDs) from biological waste materials is gaining more attention in the present-day scenario. We have synthesized highly luminescent (luminescence quantum yield, φ ​= ​19.1%), water-soluble CDs from a postconsumer waste silk cloth via a facile hydrothermal synthetic method. The resulting CDs are characterized and their photophysical properties are studied in detail. The electron transfer dynamics of CDs in presence of methyl viologen dichloride hydrate (MV2+) is systematically investigated in this work. Knowledge of the electron transfer dynamics of CDs is essential in the structural elucidation of CDs, prediction of sensing mechanisms and utilizing the CDs in energy storage devices.

Synthesis of ZnO nanostructures by hydrothermal method deposited on porous silicon for photo-conversion application

The hydro-thermal ZnO nanostructure synthesis is described in this paper. ZnO nanoparticles have been studied with the use of a scanning electron microscope (SEM), and X-ray diffraction (XRD) confirmed the formation of ZnO's hexagonal structure of the wurtzite. The produced nanostructure's average crystallite size was 21 nm. From UV–Vis absorption spectra, the bandgap of ZnO nanostructures was estimated, and the bandgap was 3.0 eV for ZnO. The porous silicon (PS) layers have been made from n-type silicon (100) orientation using the photo-electrochemical etching (PECE) process. Electrical attributes and a photodetector are utilized to characterize the product. The findings indicate that such hydrothermal synthetic method may produce high-quality ZnO nanoparticles. The photo-conversion characteristics of ZnO NPs/PS are improved, resulting in an increase in the responsivity. As a result, ZnO NPs/PS might be employed as a photodetector with a broad wavelength spectral range.

Carboxymethyl cellulose/tetracycline@UiO-66 nanocomposite hydrogel films as a potential antibacterial wound dressing

Designing an antibacterial agent with a suitable water vapor permeability, good mechanical properties, and controlled antibiotic release is a promising method for stopping bacterial infection in wound tissue. In this respect, this work aims to prepare novel flexible polymeric hydrogel films via integrating UiO-66 into the polymeric carboxymethyl cellulose (CMC) hydrogel for improving the mechanical and antibiotic release performances. First, we performed a green hydrothermal synthetic method to synthesis UiO-66 and followed by encapsulating Tetracycline (TC) through immersion in its aqueous solution. Also, the casting technique was utilized to integrate different concentrations of the TC-encapsulated UiO-66 (TC@UiO-66, 5% to 15%) in the polymeric CMC matrix (CMC/TC@UiO-66) cross-linked by citric acid and plasticized by glycerol. The release performance showed a low initial burst release with a controlled release over 72 h in the artificial sweat and simulated wound exudate (PBS, pH 7.4) media. The in vitro cytotoxicity and antibacterial activity results revealed a good cytocompatibility toward Human skin fibroblast (HFF-1) cells and a significant activity against both E. coli and S. aureus with 1.3 and 1.7 cm inhibition zone, respectively. The obtained results recommend CMC/TC@UiO-66 films as a potential antibacterial wound dressing.

Multifunctional carbon dots derived from dansyl chloride for ratiometric thermal sensor and reactive oxygen generation

Carbon quantum dots (CDs) have emerged as a promising alternative of metal-free nanomaterials for a great variety of sensor applications. In this context, the present study is devoted to the characterization of morphological and spectroscopic properties of carbon dots derived from 5-(dimethylamino)naphthalene-1-sulfonyl chloride (dansyl chloride). By using the hydrothermal synthetic method, we obtain carbon dots (CD-DsCl) co-doped with nitrogen and sulfur, which exhibit a blue emission with a good quantum yield (16%) upon photoexcitation at 320 nm. The thermal and pH effects on CD-DsCl photoluminescence are also investigated, where a pronounced modification in the fluorescence spectrum takes place as the temperature and pH are varied. Our results indicate a relevant contribution of a thermally-activated mechanism to the CD-DsCl fluorescence. Furthermore, we analyze the possibility of using CD-DsCl in nanothermometry applications, determining the absolute and relative thermal sensitivities and thermal stability of nanoparticles in the temperature range of biological systems. In addition, it is also investigated the possibility of using CD-DsCl to generate reactive oxygen species (ROS) upon photoexcitation, envisaging their use as photosensitizers in photodynamic therapy applications. Within the above scenario, the present study shows that carbon dots derived from dansyl chloride possess interesting fluorescent properties, which can be exploited as a multifunctional material.

Microwave‐Assisted Rapid Synthesis of Urchin‐Like Bimetallic Mn–Co Carbonate Composites for High‐Performance Supercapacitors

AbstractHerein, we developed a novel microwave‐assisted hydrothermal synthetic method for urchin‐like bimetallic manganese‐cobalt carbonate composites. Compared with the traditional process, the microwave‐assisted hydrothermal process is not only environmentally friendly, but also more convenient. The electrode of supercapacitors prepared at 120 °C for 10 min exhibited the best electrochemical performance, which could deliver a high capacitance of 839.58 F g−1 at 1 mA cm−2 and remain 82.12 % of its initial capacitance even after 8,000 successive charge‐discharge cycles at a high current density of 6 mA cm−2. We have found the possibility of using a microwave‐assisted hydrothermal process to synthesize the urchin‐like bimetallic manganese‐cobalt carbonate composites, which is of great importance for the application of bimetallic manganese‐cobalt carbonate composites in the supercapacitor field.

A series of porous 3D inorganic–organic hybrid framework crystalline materials based on 5-aminoisophthalic acid for photocatalytic degradation of crystal violet

Seven 3D metal-organic frameworks have been designed and synthesized by the hydrothermal synthetic method based on the ligand 5-aminoisophthalic acid. Complexes 1-4 have better photocatalytic degradation properties for dyes CV.

L-lysine-assisted hydrothermal synthesis of β-NaGdF4:Eu3+ microcrystals: Morphology evolution, luminescence and magnetic properties

Eu3+ doped β-NaGdF4 microcrystals were prepared by using an L-lysine-assisted hydrothermal synthetic method and the morphology evolution was successfully controlled. Hierarchical β-NaGdF4:Eu3+ microcrystals with different morphologies were obtained by changing the moles of L-lysine and the volume of H2O, respectively. The photoluminescence properties of the β-NaGdF4:Eu3+ samples with different morphology were comparatively discussed, in which the hollow hexagonal tube-like β-NaGdF4:Eu3+ exhibited the strongest fluorescence emission intensity owing to the high crystallinity. The characteristic luminescence properties of Tb3+-single doped, Yb3+/Er3+-, and Yb3+/Tm3+-codoped NaGdF4 microcrystals obtained in the presence of L-lysine under hydrothermal condition were also investigated. The superparamagnetic performance of β-NaGdF4:Eu3+ samples at 3 K were characterized in comparison to their paramagnetic property at 300 K, and the results indicated that all samples are paramagnetic at room temperature and the hollow tube-like β-NaGdF4:Eu3+ microcrystals exhibits best saturation magnetization values of 111.11 emu/g at 3 K. The results imply that the morphology-tunable β-NaGdF4:Eu3+ microcrystals are expected to have promising applications for micro/nano optical/magnetic functional devices.