One-step Hydrothermal Process Research Articles

Simultaneous synthesis of carbon quantum dots and porous carbon using one step hydrothermal method for supercapacitor applications

The present work reports a one-step hydrothermal carbonization process used to simultaneously produce carbon quantum dots and porous carbon. The synthesized materials were characterized by using a Fourier transform infrared spectrometer (FT-IR) to study the chemical interactions, the optical properties were studied with the help of UV-visible absorption spectroscopy, and the morphology analysis of CQDs and porous carbon was examined using FESEM, in which spherical morphology confirms the formation of CQDs, while XRD confirms the amorphous nature of the porous carbon. The application of CQDs and porous materials is evaluated as a supercapacitor material by using the cyclic voltammetry technique. The specific capacitance of porous carbon was 161.33 Fg−1 at 0.01mVs−1 scan rate. This makes CQDs and porous carbon a promising candidate for applications in energy storage devices such as supercapacitors.

Samarium doped carbon dots for near-infrared photo-therapy

Photo-assisted tumor therapy, encompassing photodynamic therapy (PDT) and photothermal therapy (PTT), has garnered considerable attention as a promising approach for tumor treatment owing to its stimuli-responsive nature and noninvasive characteristics. Carbon dots (CDs) have recently emerged as a novel type of nanomaterial with great potential in the field of anticancer therapy. However, the development of multifunctional CDs nano-platforms that integrate multiple therapeutic performance remains a challenge, especially in near-infrared (NIR) window. In this study, we synthesized samarium-doped carbon dots (Sm/CDs) via a one-step hydrothermal process for fluorescence imaging guided PTT/PDT in NIR-II window. Sm/CDs demonstrated remarkable absorption and emission properties in the NIR region, enabling efficient generation of heat energy, superoxide (•O2–) and hydroxyl radicals (•OH) under NIR irradiation. The photothermal conversion efficiencies of Sm/CDs reached up to 34.12 % and 24.38 % when exposed to 808 nm and 1060 nm wavelengths, respectively. Moreover, long-term toxicity experiments conducted in vivo as well as fluorescence experiments confirmed the potential of such functional CDs for fluorescence imaging and excellent biocompatibility. It is noteworthy that the tumor is nearly eradicated when exposed to either 808 nm or 1060 nm, demonstrating significant efficacy in both scenarios. This study provides a multifunctional CDs nano-platform that offers a promising bimodal phototherapeutic strategy to enhance the synergistic treatment of tumors through PDT and PTT.

Rational construction of bromine doped rose-like Bi2O2CO3 microspheres for enhanced visible-light-driven degradation

Optimizing the charge distribution of photocatalysts through halide ion doping has been recognized as an effective approach to enhance photocatalytic activity. Herein, the bromine doped rose-like Bi2O2CO3 microspheres were prepared through a one-step hydrothermal process. The visible diffuse reflectance spectroscopy (DRS) revealed that the bromine doping led to a narrowed band gap of Bi2O2CO3 and optimized band structure. In addition, bromine doping can achieve efficient separation of photogenerated electron-hole pairs. Thus, the photodegradation efficiency of the antibiotic oxytetracycline (OTC) and the dye rhodamine B (RhB) were significantly improved over bromine doped rose-like Bi2O2CO3 microspheres, which is 63.5% for OTC and 97.5% for RhB under visible light irradiation. The kinetic constants of the Br-Bi2O2CO3-2 material are 27.3 times for OTC and 156.2 times for RhB compared with those of pristine Bi2O2CO3. The enhanced photocatalytic performance can be attributed to the optimized carrier separation ability and broadened range of light response. The possible intermediates were identified by mass spectrometry (MS), and the degradation pathways were determined. A gradual decrease in toxicity during degradation was found by the Toxicity Estimation Software Tool (T.E.S.T). This work provides a new idea to construct high-performance photocatalysts for organic pollutants degradation.

Investigating the synergistic effects of NbCo-oxide composite electrodes in supercapacitor and water splitting applications via hydrothermal synthesis

A self-supported, binderless NbCo-oxide composite electrode was synthesized directly on a nickel foam (NF) substrate through a simple one-step hydrothermal process and utilized for energy storage and conversion applications. The optimized NbCo-oxide electrode displayed impressive energy storage capabilities, boasting an areal capacitance of 10.1 F/cm2 (equivalent to 9.10C/cm2), an energy density of 0.57 mWh/cm2, and a power density of 6.75 mW/cm2 at a 15 mA/cm2 current density. Furthermore, this electrode exhibited notable bifunctional activity, with low overpotentials of 217 mV for the hydrogen evolution reaction (HER) and 250 mV for the oxygen evolution reaction (OER) at a 10 mA/cm2 current density. The distinctive morphology, featuring rectangular blocks and plate-like microstructures, provided numerous exposed electro-active sites, facilitating efficient charge transfer, and enhancing overall electrochemical performance. The sturdy self-supporting structure on the NF substrate ensures remarkable stability, highlighting NbCo-composite materials' potential for energy storage and conversion.

Rational construction of defect-enriched α-Fe2O3/Bi2S3 composites for high-effective photocatalytic degradation of p-nitrophenol

Herein, the high-activity α-Fe2O3 (PSNF) was obtained first, and defect-enriched PSNF/Bi2S3 composites were prepared via a one-step hydrothermal process. The obtained PSNF had abundant oxygen vacancies (OV) and low bandgap energy, showing enhanced visible-light catalytic activity. Compared with PSNF and Bi2S3, the PSNF/Bi2S3 composites presented superior adsorption capacity and photocatalytic degradation activity for p-nitrophenol (p-NP). The p-NP degradation process followed the BMG model. The PSNF/Bi2S3-2 exhibited the highest photocatalytic activity, as 90.5% of the p-NP was degraded within 30 min. A tight heterojunction was formed between PSNF and Bi2S3 by the S–O bond, which effectively inhibited the recombination of photoproduced carriers and promoted the generation of OV defects. Under the synergistic effect of OV detects, photo-Fenton, and heterojunction, the generation of active species was promoted in the composite degradation system, thereby resulting in the rapid degradation of p-NP.

Engineering nanoscale nickel sulfide by a “reduction-restriction” strategy for high performance hybrid supercapacitor

Nanostructured materials usually exhibit superior electrical properties than bulk-structured materials, but conventional preparation methods are prone to produce bulk-structured nickel sulfide, leading to unsatisfactory electrochemical properties. In this work, we proposed a novel “reduction-restriction” strategy to synthesize nanoscale β-NiS via a one-step hydrothermal process. We found the introduction of strong reductants accelerates the crystal nucleation and growth of nickel sulfide, and limits further crystal growth, thus generating nanoparticles. Benefiting from the advantages brought by nanoscale effect, both of NS-15mLNaBH4 (β-NiS nanoparticles) and NS-100µLN2H4 (β-NiS nanoparticles) electrodes deliver an outstanding specific capacity of 254.1 mAh g−1 and 256.9 mAh g−1 at 1 A g−1, respectively, obviously higher than bulk-structured NS-0 (β-NiS/Ni3S4) electrode (171.0 mAh g−1 at 1 A g−1). The assembled NS-100µLN2H4//rGO hybrid supercapacitor shows a high energy density of 69.3 Wh kg−1 at a power density of 399.8 W kg−1. This work offers a novel mechanism and approach for fabrication of nanoscale metal sulfides from the perspective of controlling crystal nucleation and growth.

Synthesis of SrTiO3-TiO2-CaTiO3/Cu2O composite for stable and efficient H2 generation in deionized water and river water

Herein, the SrTiO3-TiO2-CaTiO3/Cu2O quaternary composite has been designed and prepared via one-step hydrothermal process followed by a NaBH4 reduction treatment. By comparing the H2 production rate (HPR) of Sr-Ti-Ca/Cu samples prepared by different Cu sources, it is found that Sr-Ti-Ca/Cu has the best H2 production performance when CuCl2 is as Cu source. As expected, the highest HPR of Sr-Ti-Ca/Cu sample is up to 5.088 mmol g−1 h−1, which is 195.7 times as higher as that of the Sr-Ti-Ca sample (0.026 mmol g−1 h−1) under the same conditions. Moreover, the HPR reached 0.692, 0.530 and 0.647 mmol g−1 h−1 in tap water, lake water and river water, indicating that the photocatalyst has high practicability in natural water sources. In addition, the experiment of the tap water composition effect on H2 production performance shows that NO3− and SO42− ions have great negative influence on the HPR. Compared with Sr-Ti-Ca, the light absorption of Sr-Ti-Ca/Cu extends over the entire visible region, the interface resistance decreases, and the photocurrent density increases. These results suggest that the well-designed dual p-n heterojunctions and dual type-II heterojunctions in Sr-Ti-Ca/Cu sample can enhance the light absorption in the ultraviolet region and realize the rapid separation and migration of photogenerated charge, thereby accelerating the production of H2. This work shows the strong advantage and potential of non-precious metal efficient photocatalyst system for producing H2 from deionized water and natural fresh water.

Electrical and structural engineering of nanoflower-like NiMn-layered double hydroxide by V modulation for high-performance hybrid supercapacitors

This work produced V-doped NiMn-layered double hydroxide(V-NiMnLDH) composite positive electrode material directly on nickel foam using a simple one-step hydrothermal synthesis process. The composite's 3D nanoflower-like design increased spatial utilization, surface area, and active sites for Faradaic redox reactions. The composite material has a specific capacitance of 1551 F g−1 at 1 A g−1 and 85.6 % capacitance retention at 10 A g−1, demonstrating exceptional cycle stability. In addition, we combined V-NiMnLDH with commercial activated carbon to create an asymmetric supercapacitor (ASC) with 63.5 Wh kg−1 energy density and 975 W kg−1 power density. After 5000 charge-discharge cycles, the gadget preserved 89.7 % of its specific capacitance. This material outperforms similar electrode materials in certain performance evaluations. We also used density functional theory (DFT) computations to analyze each element in the V-NiMnLDH composite and explain their electronic density of states contributions. This theoretical framework explains how V doping improves capacitance. Band structure simulations also showed V-NiMnLDH's higher charge transfer and conductivity compared to intermediate products, explaining its extraordinary capacitance performance. Our work combines theoretical and experimental data to advance catalyst design and high-performance energy storage materials.

One-step synthesis of CoxS/Ni3S2@NF on 3D nickel foam with different sulfur sources as a novel heterogeneous catalyst efficient activation of peroxymonosulfate in lomefloxacin degradation

In this study, we have successfully synthesized Co9S8/CoS/Ni3S2 and Co3S4/Ni3S2 materials in situ on three-dimensional (3D) nickel foam (NF) substrates using a one-step hydrothermal process with different sulfur sources. Under the experimental conditions of catalyst dosage of 0.50 cm × 0.50 cm and peroxymonosulfate (PMS) dosage of 0.30 g/L, the Co3S4/Ni3S2@NF catalyst exhibited superior catalytic performance in activating PMS and degrading 91.0 % of lomefloxacin (LOM) as compared to 76 % of Co9S8/CoS/Ni3S2@NF. Both Co9S8/CoS/Ni3S2@NF and Co3S4/Ni3S2@NF showed excellent stability and performed effectively over a wide pH range. The Co9S8/CoS/Ni3S2@NF and Co3S4/Ni3S2@NF demonstrated significant differences in morphology, crystal plane properties, surface functional groups, chemical composition, elemental valence states, and coordination environment as revealed by XRD, TEM, SEM, FTIR, and XPS analyses, contributing to their distinct mechanisms and performance in LOM degradation. Additionally, the NF acted as a support carrier, exposing multiple active sites to enhance electron transport and providing a nickel source for the catalytic reaction. The degradation of LOM in the CoxS/Ni3S2@NF&PMS system was thoroughly investigated, revealing the involvement of SO4−, OH, 1O2, and electron transfer in the process. Additionally, the mechanism of PMS activation and the pathway of LOM decomposition in the reaction system were elucidated by theoretical analysis. Furthermore, the ecotoxicity of the by-products generated during LOM degradation was assessed using the ECOSAR software. In summary, the CoxS/Ni3S2@NF catalysts proved to be efficient, stable, easily prepared, environmentally friendly, and recyclable heterogeneous nanocomposites. It is a promising candidate for heterogeneous PMS process.

Strategy for establishing sensitive fluorescent sensor toward p-nitrophenol integrating magnetic molecularly imprinted materials and carbon dots

In this work, a sensitive fluorescent sensor toward p-nitrophenol (4-NP) integrating magnetic molecularly imprinted materials and carbon dots (CDs) was proposed. Magnetic material and CDs derived from K3 [Fe(CN)6] and glucose were simultaneously obtained through simple one-step hydrothermal process. Introducing of molecularly imprinted materials based magnetic solid phase extraction (MSPE) endowed the constructed fluorescent sensor with higher sensitivity and selectivity. The significant factors affecting the sensitivity of the sensor toward 4-NP were optimized. Good linearity was obtained between fluorescent intensity of CDs and different concentration of 4-NP from 0.08 to 62.5 μg L−1. The sensitivity of constructed sensor was very low with detection limit of 0.02 μg L−1. Reliable applicability was also proved by the well-pleasing recoveries of 94.2–97.8% with different spiked concentrations of 4-NP in real environmental waters.

Ratiometric electrochemical determination of hydroxyl radical based on graphite paper modified with metal-organic frameworks and impregnated with salicylic acid.

Hydroxyl radical (•OH) detection is pivotal in medicine, biochemistry and environmental chemistry. Yet, electrochemical method-specific detection is challenging because of hydroxyl radicals'high reactivity and short half-life. In this study, we aimed to modify the electrode surface with a specific recognition probe for •OH. To achieve this, we conducted a one-step hydrothermal process to fabricate a CoZnMOF bimetallic organic framework directly onto conductive graphite paper (Gp). Subsequently, we introduced salicylic acid (SA) and methylene blue (MB), which easily penetrated the pores of CoZnMOF. By selectively capturing •OH by SA and leveragingtheelectrochemical signal generated by the reaction product, we successfully developed an electrochemical sensor Gp/CoZnMOF/SA + MB. The prepared sensor exhibited a good linear relationship with •OH concentrations ranging from 1.25 to 1200 nM, with a detection limit of 0.2 nM. Additionally, the sensor demonstrated excellent reproducibility and accuracy due to the incorporation of an internal reference. It exhibited remarkable selectivity for •OH detection, unaffected by otherelectrochemically active substances. The establishment of this sensor provides a way to construct MOF-modified sensors for the selective detection of other reactive oxygen species (ROS), offering a valuable experimental basis for ROS-related disease research and environmental safety investigations.

Facile and scalable synthesis of Ni3S2/Fe3O4 nanoblocks as an efficient and stable electrocatalyst for oxygen evolution reaction

This study employed a one-step hydrothermal process to synthesize Ni3S2/Fe3O4 nanoblocks in situ on nickel foam (NF). The resulting Ni3S2/Fe3O4/NF catalyst demonstrates exceptional electrocatalytic activity for the oxygen evolution reaction (OER) and robust long-term stability. It achieves a low overpotential of only 220 mV for a current density of 10 mA cm−2 with a Tafel slope of 54.1 mV dec−1 and remains stable in 1.0 M KOH for 66 h. The binder-free self-supported three-dimensional nanoblocks enhance the reaction region and long-term stability. Electronic interactions between Fe3O4 and Ni3S2, coupled with heterogeneous interfaces, optimize the electronic structure, fostering the formation of highly reactive species. Density-functional theory (DFT) calculations confirm that Ni3S2/Fe3O4, with a heterogeneous interfacial structure, modulates the chemisorption of reaction intermediates on the catalyst surface, optimizing the Gibbs free energies (ΔG) of oxygen-containing intermediates. The synergistic effect between the two active materials within the heterogeneous structure enhances OER catalytic performance. This finding offers a valuable approach to designing efficient and stable OER electrocatalysts.

Role of Zr in promoted activity of urea oxidation reaction and oxygen evolution reaction for NiFe layered double hydroxide

Electrolysis of water and splitting of urea to produce hydrogen are identified as one of the most attractive approach to reduce environmental pollution. However, this approach is both promising and challenging. In the paper, the NiFeZr LDH material was in situ grown on Ni foam through a one-step hydrothermal process. The electrochemistry activity of the NiFeZr LDH electrode was investigated by two probe reactions, one for the oxidation of urea and the other for the oxidation of water. It is worth mentioning that whether it is the oxidation reaction of urea (potential of 1.42 V @ 10 mA cm−2) or water (overpotential of 350 mV @ 10 mA cm−2), the doping of Zr improves the catalytic activity of the material. What is worth mentioning that the oxidation of urea does significantly decrease energy consumption compared to the oxidation of water. However, experiments show that the catalytic active sites are different in the two reactions. We speculate that iron is the active site for the oxidation of water, while zirconium is the active site for the oxidation of urea. Experiments demonstrate that the promoted performance is assigned to the exposure of the centre site, the rapid charge transfer rate and the improved electron configuration. Density functional theory analysis indicates that this NiFeZr LDH electrode presents optimal adsorption energy for urea, which improves the catalytic activity of the material.

Multiscale understand the tuning photocatalytic hydrogen evolution performances of BiOCl stemmed from engineered crystal facet

BiOCl photocatalyst has been extensively investigated due to unique internal electric field. However, the limited photocatalytic efficiency seriously blocks the further development of this photocatalyst. Here, using one-step hydrothermal process, we prepared the octagonal plate BiOCl, which is characterized with (110) facets. Contrasted with the ordinary BiOCl with (010) and (001) facets, the designed BiOCl-110 exbibits approximately 1.70 times and 3.15 times enhancement in photocatalytic H2 evolution, along with qualified reusability. The experimental findings collectively uncover the origin of high hydrogen production, which (110) facet greatly prolongs the lifetime of carriers, sharply increases the surface photovoltage and reasonably optimizes the carrier transport. Particularly, density functional theory simulations unveil a remarkably reduced transition between valence band maximum and conduction band minimum within BiOCl-110, resulting in a largely increased carrier extraction. Besides, the optimized free energy barriers of intermediates yield proper adsorption and desorption process in overall H2O splitting. Further ab initio molecular dynamics calculations unlock that the distinctive atomic structure on surface of the octagonal plate BiOCl serves as the inherent factor in regulating the element distribution of H2O layer on photocatalyst surface. The facet-dependent electronic structure and facet/H2O interface effects offer crucial understanding for BiOCl in highly effective hydrogen evolution.

Hierarchical Mg/Al hydrotalcite oxide hollow microspheres with excellent adsorption capability towards Congo red.

A novel citrate anion-intercalated Mg/Al layered double hydroxide (CA-LDH) is synthesized via a one-step hydrothermal process. The synthesized CA-LDH is a hollow flower-like microsphere composed of thin nanoflakes (10 nm in thickness). After calcination, the formed Mg/Al layered double oxide (CA-LDO) hollow microspheres possess a high specific surface area of 247.8 m2 g-1 and a high pore volume of 0.97 cm3 g-1, which endow them with excellent adsorption ability towards Congo red (CR). The maximum adsorption capacity of CR onto CA-LDO can reach up to 1883 mg g-1. The significantly improved adsorption capacity of CA-LDO can be attributed to its unique structures of hierarchical hollow microspheres, in which the hierarchical porous shell layer provides enough adsorption sites to anchor the dye molecules, and the hollow core can preserve the absorbed dye. This study provides a promising novel adsorbent which can be used for efficient water remediation.

Current collector-free symmetric μ-supercapacitor based on a ternary composite of graphene, polydopamine and Co3O4

A nanocomposite of reduced graphene oxide, polydopamine, and Co3O4 was developed via a one-step hydrothermal process, which showed remarkable electrochemical properties, when used as electrodes in a current collector-free μ-supercapacitor device.

Enhanced properties of gelatin films incorporated with TiO2-loaded reduced graphene oxide aerogel microspheres for active food packaging applications

The synergistic effect of graphene sheets and titanium dioxide nanoparticles (TiO2) hybrid fillers can improve the antibacterial, mechanical, and barrier properties of gelatin (GL), making it more suitable to be used in the food packaging application. However, the uneven dispersion and aggregation of the hybrid fillers restrict its performance for further application. In order to achieve the above superior properties, reduced graphene oxide aerogel microspheres (rGOAMs) loaded with TiO2 (rGOAMs@TiO2) were successfully prepared using one-step hydrothermal process by reducing titanium sulfate into TiO2 on the framework of rGOAMs, followed by effective dispersion in the GL matrix to form nanocomposites (rGOAMs@TiO2/GL) through simultaneous ultrasonication and mechanical stirring, as well as an ultrasonic cell grinder process. Incorporating a mere 0.8 wt% of rGOAMs@TiO2 effectively improved the mechanical, antibacterial, UV light barrier, thermal stability, hydrophobicity, and water vapor barrier properties of the GL. Compared with the composites made of rGOAMs, TiO2, and GL (rGOAMs/TiO2/GL), rGOAMs@TiO2/GL composites showed stronger filler-matrix interactions, better filler dispersion, and lower TiO2 particle aggregation, suggesting superiority compared to rGOAMs/TiO2/GL composites at the same filler content. This innovative method of mixing GL with rGOAMs@TiO2 holds great promise for enhancing the suitability of GL in active food packaging applications.

Co@MoS2 Nanocatalyst: Enhanced Activation of Peroxymonosulfate for Effective Degradation of Sulfadiazine

To improve the activation efficiency of PMS to efficiently degrade antibiotic sulfadiazine (SD), herein, a Co@MoS2 catalyst was prepared by a one-step hydrothermal process. The unique petal-like structure of MoS2 enables the transition metal Co to achieve high dispersion and avoid agglomeration. Mo(IV) and unsaturated S accelerate the electron transfer between Co[Formula: see text] and Co[Formula: see text] to improve the cycling efficiency and thus realize the efficient activation of PMS. The results of active substance quenching experiment and ESR analysis show that the main active substance for the efficient degradation of SD by Co@MoS2 is the non-radical 1O2, while the other three radicals [Formula: see text], ⋅OH and [Formula: see text] contribute significantly to the efficient degradation of SD. And after 5 cycles, the degradation could still be as high as 90%. The strong consolidation of Co on the petal-shaped sheet of MoS2 ensures the stability of Co@MoS2 catalyst.

SnO2/Sn with core-shell structure Schottky heterojunctions loaded in graphene to promote electrochemical reaction kinetics and enable efficient lithium-ion storage.

The stannic oxide (SnO2) anode expands in volume during cycling causing a decrease in reversible capacity. In this work, we generated a spherical SnO2/Sn heterojunction with core-shell structure composites encapsulated by graphene (SnO2/Sn/G) in situ using a simple one-step hydrothermal and subsequent annealing process. SnO2/Sn heterojunction nanospheres dispersed in a porous graphene framework accelerate the diffusion kinetics of electrons and ions. In addition, the structure plays a key role in mitigating large volume changes and nanostructure agglomeration. As a result, SnO2/Sn/G exhibits excellent performance as an anode material for lithium-ion batteries (LIBs), maintaining a reversible specific capacity of 720.6 mA h g-1 even after 600 cycles at a current density of 0.5 A g-1.

NaLuF4:RE3+ (Dy3+, Tb3+, Eu3+, Tm3+): controllable morphology, multicolor light.

A series of emission-tunable NaLuF4:RE3+ (RE = Dy, Tb, Eu, Tm) phosphors were firstly synthesized by a glycine assisted one-step hydrothermal process. The structure and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results revealed that the samples were Na5Lu9F32, LuF3 and NaLuF4 and the size and shape of the products could be tuned just by adjusting the pH values of the initial reaction solutions or by adjusting the RE3+/NaF ratio or RE3+/NaBF4 ratio. The morphologies for the products include irregular particles, irregular blocks, octahedral shapes, hexagons, or micron sized hexagonal prisms. Furthermore, the photoluminescence properties of NaLuF4:Dy3+,Tb3+, NaLuF4:Tb3+,Eu3+, NaLuF4:Dy3+,Eu3+ and NaLuF4:Tm3+,Dy3+ were investigated in detail. Additionally, when co-doping Dy3+ with Tb3+ or Eu3+ or co-doping Tb3+with Eu3+ or co-doping Tm3+ with Dy3+ ions in the single component, colorful emission can be obtained by giving abundant blue, green, yellow, orange, and especially white-light-emission. All these properties indicate that the developed phosphor may potentially be used as single-component multicolor-emitting phosphors.