Solvothermal Approach Research Articles

Novel cobalt-incorporated two dimensional covalent organic frameworks for supercapacitor applications

Covalent-organic frameworks (COFs), are a promising new class of crystalline porous organic materials with confined structures either in 2D or 3D domains. The current study focuses on using a solvothermal approach consisting of sealed pyrex tubes to synthesize two-dimensional TBP-COF and TBP-COF that have been doped with cobalt (Co) (TBP-Co@COF). The results of the experimentally acquired X-ray diffraction study were compared with those from simulations, and it was discovered that both are in good agreement. A thorough theoretical analysis of the layer packing in AA stacking (P1) and AB stacking (P1) modes using the Materials Studio revealed that AA stacking is more stable than the AB stacking (P1) structure. The formation of imine linkage and incorporation of Co into the COF are indicated by the result of XPS. Unaggregated dispersion of Co particles can be seen on the square and rectangular sheets of TBP-COF in TEM and SEM images. Both materials are fabricated as electrode materials and evaluated for their supercapacitor applications. The TBP-Co@COF shows an enhanced specific capacitance (CSp) of 975F/g compared to the TBP-COF (827F/g) at 2 mV/s scan rate. TBP-Co@COF exhibit an energy density (ED) of 69 Wh/kg even at a high power density (PD) of 75000 W/kg and also retains 79 % of its initial capacitance up to 2000 cycles. TBP-COF and TBP-Co@COF were fabricated for an asymmetric supercapacitor device (ASD) and found to exhibit a CSp of 191F/g at a scan rate of 2 mV/s.

Rationally designed MIL-101(Fe)/WO3 S-scheme heterojunction coupled with peroxymonosulfate for boosting the visible-light-driven photodegradation of tetracycline hydrochloride

Developing S-scheme photocatalysts with excellent catalytic activity and convenient retrieval is highly desirable for wastewater purification. Herein, a novel S-scheme MIL-101(Fe)/WO3 heterojunction on carbon cloth is successfully synthesized via a facile solvothermal approach. The optimized MIL-101(Fe)/WO3 composite (MWC-1.5) has been found to be highly effective in activating peroxymonosulfate (PMS) and then degrading tetracycline hydrochloride (TC-HCl) with a 100% degradation rate when exposed to visible light (Vis) within a period of 20 min. Such MWC-1.5/PMS/Light system also shows stable cycling performance and good recyclability. The remarkable photocatalytic degradation performance is mainly attributed to the powerful intrinsic electric field that accelerates the separation of photogenerated charge carriers via the S-scheme charge transfer. Radical quenching experiments and electron paramagnetic resonance (EPR) results suggest that SO4– and OH are the major oxidizing substances in the photocatalytic processes. Three potential degradation pathways are deduced based on an in-depth analysis of the degradation intermediates and the degradation mechanism is also elucidated through a rational combination of the experimental studies and theoretical calculations. This novel hybrid photocatalyst system has been shown to be a promising strategy for environmental remediation, while also suggesting a feasible approach for the development of photocatalysts with both remarkable activity and stability.

Interfacial Electronic Interactions Between Ultrathin NiFe-MOF Nanosheets and Ir Nanoparticles Heterojunctions Leading to Efficient Overall Water Splitting.

Creating specific noble metal/metal-organic framework (MOF) heterojunction nanostructures represents an effective strategy to promote water electrolysis but remains rather challenging. Herein, a heterojunction electrocatalyst is developed by growing Ir nanoparticles on ultrathin NiFe-MOF nanosheets supported by nickel foam (NF) via a readily accessible solvothermal approach and subsequent redox strategy. Because of the electronic interactions between Ir nanoparticles and NiFe-MOF nanosheets, the optimized Ir@NiFe-MOF/NF catalyst exhibits exceptional bifunctional performance for the hydrogen evolution reaction (HER) (η10 = 15mV, η denotes the overpotential) and oxygen evolution reaction (OER) (η10 = 213mV) in 1.0m KOH solution, superior to commercial and recently reported electrocatalysts. Density functional theory calculations are used to further investigate the electronic interactions between Ir nanoparticles and NiFe-MOF nanosheets, shedding light on the mechanisms behind the enhanced HER and OER performance. This work details a promising approach for the design and development of efficient electrocatalysts for overall water splitting.

Green Synthesis of Baby Pumpkin Derived Fluorescent Carbon Dots – A Potent Label‐Free Probe for Cd2+ Determination

AbstractThis study demonstrates a facile solvothermal approach to synthesizing green fluorescent carbon dots (G‐CDs) using baby pumpkin as a natural precursor. The G‐CDs exhibit strong fluorescence emission at 547 nm under excitation at 467 nm, and the highest quantum yield reaching 17.5 % in acetone, making them suitable for a range of applications including sensing, bioimaging, catalysis, and drug delivery. The G‐CDs demonstrate excellent stability under various conditions, such as prolonged light exposure, high salt concentration, extended periods, and elevated temperatures. Furthermore, the G‐CDs show a good linear relationship with Cd2+ within the concentration range of 0 to 16.5 μmol/L, with a linear correlation coefficient of 0.9920. The detection limit (LOD) was calculated to be 0.68 μmol/L. The recovery rate ranges between 85.66% to 97.43%, indicating their potential for use in environmental metal ion detection. This study provides a convenient and economical method for the synthesis of G‐CDs using baby pumpkin as a precursor, offering a sustainable alternative for various applications in sensing, imaging, catalysis, and drug delivery.

Influence of PVP on the properties of solvothermally synthesized famatinite nanoparticles: Structural, morphological and optical insights

Famatinite (Cu3SbS4) nanoparticles were synthesized through a solvothermal approach using various polyvinylpyrrolidone (PVP) ratios as a capping agent with a binary solvent of ethylene glycol and water in equal parts. Incremental additions of PVP, ranging from 0 to 1.5 g, exerted significant influence on the material's characteristics. Through comprehensive analysis involving X-ray diffraction, Raman spectroscopy, Scanning electron microscopy (SEM) with Energy dispersive spectrometer (EDS), and UV diffuse reflectance spectroscopy, critical insights were obtained. XRD analysis confirmed the tetragonal crystal structure and revealed reduced crystallite sizes due to the incorporation of PVP. Raman spectroscopy validated the presence of pure famatinite phase with 0.5 g and 1.0 g PVP. SEM analysis uniformly depicted a spherical morphology in all samples, emphasizing PVP's role in mitigating nanoparticle agglomeration. UV diffuse reflectance spectroscopy disclosed direct bandgaps falling within the 0.88 – 0.97 eV range. The collective findings highlighted the substantial impact of PVP in the binary solvent on the structural, morphological, and optical properties of Cu3SbS4 nanoparticles. These results underscore the potential application of these tailored nanoparticles as promising candidates for advanced photovoltaic absorber materials.

Carbon and Nitrogen‐Co‐Doped Se/NiSe2/CoSe2 Nanocomposite as Superior Performance Electrode Material in Hybrid Supercapacitors

AbstractMetal selenides are essential electrode materials for promising electrochemical energy storage with comparable or improved electrochemical performance than metal oxides. Herein, Se/NiSe2/CoSe2 (S/NS/CS) is fabricated using a solvothermal approach with the assistance of polyethyleneimine, followed by annealing at different temperatures (300, 400, 500, and 600 °C) for one hour under an argon atmosphere. After annealing, all electrodes’ physical and electrochemical properties were examined, which determined that the best electrode is NiCo2O4/NiO (NCO/NO) formed at 500 °C. Additional hydrothermal method uses NCO/NO with SeO2 as a selenium source to prepare S/NS/CS nanocomposite, with a specific surface architecture that enables easy ion movement and robust conductivity, giving it exceptional electrochemical energy storage properties. It exhibited a remarkable capacitance of 468 F g−1 at a current density of 0.5 A g−1. For practical applications, the hybrid S/NS/CS//AC device was designed using S/NS/CS as a positive electrode and commercial activated carbon (AC) as a negative electrode. The asymmetric device demonstrated an excellent capacitance of 142 F g−1 (189 C g−1) and a superb specific energy of 44 Wh kg−1 at a specific power of 840 W kg−1 at a current density of 1 A g−1, providing 80 % capacity retention and 100 % coulombic efficiency after 5000 cycles.

Enhanced CO2 photoreduction over bismuth-rich Bi4O5Br2: Optimized charge separation and intrinsic barriers

Photocatalytic CO2 conversion into chemicals is one of effectively strategies to overcoming the energy crisis and global warming. However, the CO2 photoreduction efficiency is hindered by poor charge separation and CO2 activation. The composition regulation of photocatalyst is an effective strategy to solve these issues. Herein, we constructed the Bi4O5Br2 in ionic liquid through a solvothermal approach. The local internal electric field of photocatalyst has been regulated over Bi4O5Br2 through Bi-rich strategy, achieving enhanced charge separation and long carrier lifetime. Density-functional theory (DFT) calculations found that the intrinsic barriers for CO2 adsorption-activation can be effectively optimized over Bi4O5Br2, promoting the CO2 dissociation and facilitating the generation of *COOH. Therefore, Bi4O5Br2 possesses improved evolution rates of 23.81 and 1.33 μmol g−1 for CO and CH4 under irradiation of 300 W Xe lamp for 4 h. This work provides a new strategy for the rational construction of efficient materials towards solar-driven energy conversion.

Electrochemical performance of SnS-SnS2@CNTs composites as anode materials for Sodium ion batteries

Tin sulfide based materials are attracting attention because of excellent performance as SIBs anode. However, SnS and SnS2 suffer from severe capacity degradation during the charge/discharge process, as well as high volume expansion, which prevents superior cycling stability of SIBs. In this work, carbon nanotubes (CNTs) modified SnS-SnS2 materials were prepared by a facile one-step solvothermal approach. The constructed SnS-SnS2 heterostructures have a special internal electric field that promotes charge transfer. The combination of CNTs also prevents agglomeration of active particles and improves the capacity and cycling durability of SIBs (413 mAh·g−1 after 50 cycles).

Solvothermal Shaping of Imine‐Linked Covalent Organic Frameworks by a Two‐Step Solvent Feeding Process

AbstractSolvothermal synthesis is the predominant method for creating new structured covalent organic frameworks (COFs), yet it grapples with challenges in controlling shape and morphology. This issue is attributed to the unregulated solvent‐feeding process, which results in rapid polymerization and uncontrolled phase separation. Consequently, a two‐step solvent‐feeding process is reported for the solvothermal shaping of imine‐linked COF monoliths with hierarchical porosity. The synthesis conditions for COF powders reported in existing literature are directly utilized without extensive optimization; however, solvents are divided into two segments prior to feeding. A minor segment of solvents is employed to dissolve monomers, which polymerize in situ to form amorphous monoliths. Subsequently, the remaining organic solvent, along with an acetic acid aqueous solution, is added for crystallization. The versatility of this two‐step feeding process in producing COF monoliths is illustrated. The high‐quality COF monoliths demonstrate benzene uptakes ranging from 6.0 to 16.8 mmol g−1 at 298 K. This study confirms that the two‐step solvent feeding process can be effectively integrated with the conventional solvothermal method to enhance the solution‐processability of COFs. It is anticipated that this modified solvothermal approach can readily shape COFs to meet practical application requirements.

Efficient Adsorption of Methylene Blue Using a Hierarchically Structured Metal-Organic Framework Derived from Layered Double Hydroxide.

The growing concerns about environmental pollution, particularly water pollution, are causing an increasing alarm in modern society. One promising approach to address this issue involves engineering existing materials to enhance their effectiveness. A one-step solvothermal reconstruction approach was used to build an eco-friendly two-dimensional (2D) AlNiZn-LDH/BDC MOF composite. The characterizations confirm the formation of a metal-organic framework (MOF) at the layered double hydroxide (LDH) surface. The resulting synthesized material, 2D AlNiZn-LDH/BDC MOF, demonstrated remarkable efficacy in decontaminating methylene blue (MB), a model cationic dye found in water systems. The removal performance of 2D AlNiZn-LDH/BDC MOF was significantly higher than that of pristine 2D AlNiZn-LDH. This improvement shows the potential to increase the adsorption capabilities of nanoporous LDH materials by incorporating organic ligands and integrating meso-/microporosity through MOF formation on their surfaces. Furthermore, their kinetic, isothermal, and thermodynamic studies elucidated the adsorption behavior of this composite material. The results of synthesized MOF showed excellent removal efficiency (92.27%) of 10 ppm of MB aqueous solution as compared to pristine LDH. Additionally, the as-synthesized adsorbent could be regenerated for six successive cycles. This method holds promise for the synthesis of novel and highly effective materials to combat water pollution, laying the groundwork for potential advancements in diverse applications.

Comparing Three Methods for Producing Carbon Dots from Mangosteen Peel

Carbon dots are fluorescent nanoparticles that are around 10 nm in size. Carbon dots can be formed via pyrolysis, hydrothermal, and solvothermal procedures from raw materials such as mangosteen peels. Because it contains cyanidin and xanthone, which improve the intensity of carbon dot fluorescence, mangosteen peel waste can be utilized to make carbon dots. The presence of a urea passivation agent is expected to boost carbon dot luminescence intensity. The study aimed to develop carbon dots from mangosteen peel using three different methods: pyrolysis, hydrothermal, and solvothermal, and to assess their ability to produce luminous hues. Carbon dot yield was 21% by the solvothermal method, 5% by the hydrothermal method, and 2% by pyrolysis. All three methods produced blue carbon dot luminescence. The solvothermal method, hydrothermal procedure, and pyrolysis had the highest luminescence intensity. Adding urea as a passivation agent increased the luminescence of carbon dots. The solvothermal approach produced the highest carbon dot production and fluorescence intensity. The hydrothermal and solvothermal carbon dots made emissions at wavelengths of 413 nm and 454 nm, respectively, both corresponding to blue luminescence.

Carbon dots derived from green jujube as chemosensor for tetracycline detection

The detection of tetracycline antibiotics in environmental waters is crucial due to their widespread use, persistence, and potential toxicity. Herein, highly fluorescent blue-emitting carbon dots (B-CDs) were synthesized via a facile, green solvothermal approach using green jujube as the carbon source and ethylenediamine as the nitrogen dopant. The B-CDs exhibited an exceptional quantum yield of 24.7% in ethanol along with excitation-dependent photoluminescence from surface defects. Remarkably, the B-CDs displayed high selectivity and sensitivity toward tetracycline antibiotics through static quenching and inner filter effects. A linear correlation between fluorescence quenching and tetracycline concentration enabled quantitative detection down to 0.061 μM. The feasibility of using B-CDs for antibiotic sensing in real waters was validated by spike-recovery experiments achieving 95.4%–100.2% recoveries. The findings provide insights into natural product-derived carbon nanomaterials while offering an eco-friendly sensing platform with potential for on-site antibiotic monitoring and environmental remediation.

Synergistic Effects of Amine Functional Groups and Enriched-Atomic-Iron Sites in Carbon Dots for Industrial-Current-Density CO2 Electroreduction.

Metal phthalocyanine molecules with Me-N4 centers have shown promise in electrocatalytic CO2 reduction (eCO2R) for CO generation. However, iron phthalocyanine (FePc) is an exception, exhibiting negligible eCO2R activity due to a higher CO2 to *COOH conversion barrier and stronger *CO binding energy. Here, amine functional groups onto atomic-Fe-rich carbon dots (Af-Fe-CDs) are introduced via a one-step solvothermal molecule fusion approach. Af-Fe-CDs feature well-defined Fe-N4 active sites and an impressive Fe loading (up to 8.5wt%). The synergistic effect between Fe-N4 active centers and electron-donating amine functional groups in Af-Fe-CDs yielded outstanding CO2-to-CO conversion performance. At industrial-relevant current densities exceeding 400mA cm-2 in a flow cell, Af-Fe-CDs achieved >92% selectivity, surpassing state-of-the-art CO2-to-CO electrocatalysts. The in situ electrochemical FTIR characterization combined with theoretical calculations elucidated that Fe-N4 integration with amine functional groups in Af-Fe-CDs significantly reduced energy barriers for *COOH intermediate formation and *CO desorption, enhancing eCO2R efficiency. The proposed synergistic effect offers a promising avenue for high-efficiency catalysts with elevated atomic-metal loadings.

Synthesis of cerium-doped gadolinium gallium aluminum garnet (GGAG:Ce) scintillating powder via solvothermal method

The powder material Gd3Ga3Al2O12:Ce (GGAG doped with Cerium) has garnered significant attention in radiation detection due to its high light yield and rapid decay time. Despite its potential, the synthesis of high-quality and reproducible GGAG:Ce scintillating powder remains a considerable challenge. In this study, we present a solvothermal approach with an annealing temperature of 1300 °C for producing cerium-doped GGAG powder with varying concentrations (4, 2, and 0.5 mol%). The structural and luminescent characteristics were meticulously examined using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL), radioluminescence (RL) spectroscopy, and X-ray photoelectron spectroscopy (XPS). XRD analysis confirmed the single-cubic phase garnet structure of the synthesized powder. By comparing the intermediate solvothermal products synthesized at different sintering temperatures (900 °C for 3 h and 1300 °C for 1 and 3 h), a direct correlation between solvothermal conditions and the structure/property relationships of the product was established. FESEM images revealed an ellipsoidal to irregular morphology of the as-synthesized GGAG:Ce microparticles, ranging from 0.1 to 0.3 μm, regardless of the Ce concentration. PL spectra demonstrated a strong emission peak at approximately 550 nm, characteristic of Ce3+ ions. RL data confirmed the peak luminescence at around 550 nm, with an almost twofold increase in intensity as the concentration of Ce3+ increased from 0.5 mol% to 4 mol%. XPS data disclosed the Ce3+/Ce4+ ratio in solvothermally synthesized GGAG:Ce, wherein Ce loading of 4 mol% demonstrated the increase in Ce3+ concentration to 95%, whereas the concentration of Ce4+ decreased to 5%. Notably, the highest luminescence efficiency was achieved with GGAG:Ce at a 4 mol% concentration. Thus, the solvothermal method employed in GGAG:Ce synthesis presents a straightforward approach, yielding rapid results with precise control over particle morphology and size.

Adsorption and DFT investigations of Cr(VI) removal using nanocrystals decorated with graphene oxide

In this research, a solvothermal approach is introduced to synthesize a metal-organic frameworks (MOFs) nanocomposite (GO/UiO-66-NDC) for the removal of Cr(VI) from water. A comprehensive analysis was performed to understand the physical, chemical, and structural properties of the MOF nanocomposite. The adsorption behavior of Cr(VI) was investigated by changing various parameters, such as pH, dosage, and concentration, to determine isotherms, thermodynamics, and kinetics. The results showed that the nanocomposite had a high tolerance to pH and thermal stability, with a high adsorption capacity of 157.23 mg g−1 for Cr(VI) at pH 3 due to the presence of zirconium oxide clusters. The density functional theory simulations showed that the nanocomposite had ten times more dynamic delocalized surface states, which enhanced the adsorption capacity and agreed with the experimental results. Furthermore, the nanocomposite exhibited better regeneration performance compared to previously reported materials, making it a promising super-adsorbent for removing Cr(VI) from water.

Silver-infused TiO2 nanowires and unveiling their potential for superior wastewater dye remediations.

Silver infused ultrathin TiO2 nanowires (NWs) were synthesized via a single step solvothermal approach. The crystallinity, structure, and morphology were determined to understand the physicochemical nature of the nanocomposites. The catalytic efficiency of the newly synthesized nanocatalysts was tested for the textile waste treatment taking methylene blue (MB) as model pollutant under solar light irradiations. Nearly 96% photodegradation efficiency for MB was achieved within 20 min. Furthermore, the recyclability of the photocatalyst was also studied, and the material remained stable and effective up to four consecutive runs. RESEARCH HIGHLIGHTS: Precise size-controlled synthesis of Ag-incorporated titania nanowires (ATNWs) Controlled aspect ratios, with tunable lengths and diameters (100-3 nm) via precursor and surfactant optimization Demonstrated ATNWs' efficiency in degrading toxic dye, methylene blue (MB) 96% photodegradation efficiency for MB achieved within 20 min using 3 nm thick annealed TiO2 NWs Recyclability efficiency of photocatalyst, which remained stable and effective for up to four consecutive runs.

Synthesis and characterizations of Cu2MgSnS4 nanoparticles by solvothermal method

Cu2MgSnS4 (CMTS) nanoparticles are successfully prepared via a solvothermal approach. X-ray diffraction (XRD) and Raman reveal that pure zinc-blende CMTS phase is obtained. Scanning electron microscopy (SEM) shows that CMTS nanoparticles exhibit microsphere structure. The band gap of as-obtained CMTS nanoparticles is calculated to be 1.68eV, indicating a potential candidate for tandem solar cells. The degradation rate of methylene blue (MB) with under visible-light irradiation is about 87%, indicating that CMTS can be useful for effective visible-light photocatalyst.

Thermal-based Zinc-Oxide-Coated Smart Fabric for Thermochromic Applications

The present study focuses on developing a thermochromic device with a flexible substrate through the coating of cotton fabric with ZnO (Zinc oxide) by solvothermal synthesis technique. Here, ZnO is used as the thermochromic layer for the fabrication work, and it is suitable for textile and wearable applications as it is non-toxic to human skin. This device is designed and fabricated in order to gain better insight into the role of ZnO in thermochromic applications. Here, 3D nanostructures of ZnO are grown on the surface of cotton fabric using a simple and cost-effective solvothermal synthesis approach. The coated fabrics are investigated to determine their structure, morphology, composition, electrical, optical and emissivity properties using an X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), current-voltage (I-V) characteristics, ultraviolet protection factor (UPF) etc. From the morphology study, uniformly packed ZnO nanorods with growth in the c-axis direction are observed. The ZnO nanostructures are known to have excellent UPF when exposed to solar radiation and showed UPF value of 112.48. It is found that coated fabrics have increased electrical conductivity under optical excitations and also enhanced the reflectance. Moreover, based on the emissivity analysis coated ZnO cotton fabric showed the emissivity of 0.95, which is higher and has greater radiation protection than that of bare cotton fabric. Hence, the developed thermochromic device has potential for use in the future in textile and wearable based thermochromic application.

Selective N-formylation of amines and carbon dioxide through the utilization of Nd2Sn2O7 supported by Ar-g-C3N4 on dendritic filamentous nanotitanium

Nd2Sn2O7 NPs were synthesized by employing a straightforward synthetic method along with aromatic ring-doped g-C3N4 nanosheets loaded onto dendritic filamentous nanotitanium (DFNT/Ar-g-C3N4@Nd2Sn2O7). The inclusion of DFNT in this process was found to offer an abundance of O-H groups for the uniform charging of g-C3N4 through chemical bonding interaction. The topography and mesoporous anatomy of the DFNT/Ar-g-C3N4@Nd2Sn2O7 composite remained unchanged upon Ar-g-C3N4@Nd2Sn2O7 loading, indicating the sustained crystalline shape. This extraordinary catalyst exhibits a noteworthy capacity in facilitating the N-formylation reaction by establishing N-C bonds through the reaction between amine and carbon dioxide, all while conforming to environmentally favourable circumstances. Here, the DFNT/Ar-g-C3N4@Nd2Sn2O7 photocatalyst was synthesized utilizing a solvothermal approach for the N-formylation of N-methylaniline. The main products obtained were mono-N-formylated compounds, with favourable to excellent yields for all amines. Lastly, an explanation for the reaction between amine and carbon dioxide is put forward by conducting control experiments and verifying spectra.

A highly selective fluorescent biosensor based on sulfur quantum dots for iron (III) detection

In this study, sulfur quantum dots (SQDs) were synthesized via an easy one-step solvothermal approach, and for the first time polyvinylpyrrolidone (PVP) was used as a capping agent that resulted in the synthesized SQDs with ultra-small size (3.57 nm), good photoluminescence, excellent stability, hydrophilicity, and rich functional groups surface. As a result of these features, SQDs were able to detect ferric ions (Fe3+) with fast rate responsiveness in acidic environments (pH=3) and in the existence of interferents with a limit of detection (LOD) of 48 nM and the detection range of 0 to 250 µM. Moreover, the cytotoxicity of SQDs was examined based on fibroblast normal cells (L929) and cervical cancer cells (HeLa). SQDs showed biocompatibility and extremely low toxicity towards both cell types even at high concentrations (250 µg/mL). This proposed method showed that SQDs as simple and portable sensors are promising for Fe3+ detection that can be applied in acidic environments and real samples with acceptable results.