Hydrothermal Treatment Route Research Articles

Bimetallic ZIF-derived cobalt nanoparticles anchored on N- and S-codoped porous carbon nanofibers as cathode catalyst for Li-O2 batteries

Metal-organic frameworks (MOFs) have shown great application potential for improving Lithium-oxygen (Li-O2) batteries performance with high O2 affinity and accessible active centers. Herein, a novel type of cobalt nanoparticles embedded in porous nitrogen (N)- and sulfur (S)-codoped carbon nanofiber (Co@N/S-CNF) structure is developed by employing electrospinning technology and bimetallic zeolitic imidazole framework (ZIF-8/ZIF-67, a kind of MOF) precursor with the following annealing and hydrothermal treatment route. When utilized as cathode catalysts for Li-O2 batteries, the Co@N/S-CNF sample exhibits higher discharge capacity (9290.7 mAh g−1 at 50 mA g−1) and better cycling stability (42 cycles at 100 mA g−1 under a curtailing capacity of 500 mAh g−1) compared to Co@N-CNF electrode. The enhanced performance can be attributed to the 1D porous morphology and N/S doping effect, which can effectively improve mass transport, increase exposed active sites, and induce structural defect, thereby accelerating the formation and decomposition progress of discharge products. This simple synthetic strategy may provide a new insight for designing and developing MOFs-based multifunctional catalysts in the field of energy and electrocatalysis.

Modified hydrothermal treatment route for high-yield preparation of nanosized ZrO2

Nanosized ZrO2 particles are applied in high-performance thermal barrier coatings and catalyst carriers. To synthesize nanosized zirconia, precipitation from aqueous solutions followed by hydrothermal treatment is widely conducted. In this work, a modified hydrothermal treatment route is described for high-yield fabrication of well-dispersible nanosized t–ZrO2. Zirconium oxychloride and sodium hydroxide were used as the precursor and precipitant, respectively. N, N-bis(2-hydroxyethyl) glycine (bicine) was used as surface stabilizer to inhibit the early agglomeration of nuclei, and ultrasonication was used to enhance the dispersion of ZrO2 nanocrystals. The hydrothermal treatment was optimized for reaction temperature, time, fill fraction, and solid content. The synthesized zirconia was characterized using X-ray diffraction, dynamic light scattering, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The yield of zirconia increased to 134 g/L after hydrothermal. Tetragonal ZrO2 obtained with hydrothermal treatment at 200 °C for 8 h at a fill fraction of 80% has a good dispersibility, with an average particle size of 20 nm and a narrow size distribution.

Synergy of interlayer expansion and capacitive contribution promoting sodium ion storage in S, N-Doped mesoporous carbon nanofiber

Heteroatoms doping is proved to be an effective strategy to improve the electrochemical performance of carbon materials by adjusting its physical and chemical properties. In this work, sulfur, nitrogen co-doped carbon nanofiber (SNCNF) is prepared by electrospinning technique with the following heat and hydrothermal treatment route. Benefiting from the S, N co-doping, SNCNF demonstrates perfect pseudocapacitance characteristic improving rate performance (N-doping) and large interlayer distances promoting reversible insertion/extraction of Na+ (S-doping). SCNNF displays high charge-discharge specific capacity (290.3 mA h g−1 at 0.1 A g−1), superior cycling stability (247.4 mA h g−1 and 98.2% retention at 0.5 A g−1 over 600 cycles) and ultra-long circulation characteristics at high current rate (160.2 mA h g−1 at 10.0 A g−1 after 10,000 cycles), which can be served as a very promising material as anode for sodium ion batteries.

Novel multi-wavelength effectively excited ZnWO4-WO3:Eu3+ multiphase red phosphor for white light-emitting diodes

The discovery of phosphor with efficient red emission is a crucial step in the development of the white light-emitting diodes (wLEDs). Herein, based on the regulation of the W/Zn ratio, the Eu3+-activated ZnWO4-WO3∙0.5H2O-WO3 multiphase phosphor was designed successfully via the one-step hydrothermal treatment route. The effects of the W/Zn ratio on the phase structure, composition, morphology, luminescence property and lifetime of the obtained samples were systematically and comparatively investigated. The obtained product not only maintains the multi-wavelength excitation feature of ZnWO4:Eu3+ phosphor, but also sharply improves the characteristic emission intensity of Eu3+ ions. It is found that the WO3∙0.5H2O crystal has a special 3D interconnected channel structure, which is a relatively much access to the chemical behavior and permits the ready insertion of part of Eu3+ ions, and this coordination environment can obtain strong pure red light emission. Further, the ZnWO4-WO3:Eu3+ phosphor obtained after dehydration treatment can be excited more efficiently in the deep-ultraviolet (DUV), near-ultraviolet (NUV) and blue light regions, and its quantum efficiencies reach 18%, 22% and 21.2%, respectively. Besides, it also exhibits better CIE chromaticity coordinate, higher color purity than commercial Y2O2S:Eu3+ phosphor. Therefore, the ZnWO4-WO3:Eu3+ is promising for the application in red phosphor with different wavelengths for wLEDs.

Facile hydrothermal treatment route of reed straw-derived hard carbon for high performance sodium ion battery

Although hard carbon is deemed to be the most potential industrialized sodium-ion batteries anode material, there are still some problems need to be solved. In this study, a waste biomass of reed straw is pretreated by using a new strategy-hydrothermal treatment instead of pickling and successfully transformed to hard carbon materials through subsequent carbonization process. The reed straw carbonized at 1300 °C exhibits an impressively high reversible capacity of 372.0 mAh g−1 with excellent initial coulombic efficiency of 77.03% and outstanding cycling stability. Significantly, the sodium storage mechanism in our electrodes is mainly summarized into two models. Moreover, we find the interlayer spacing of graphite-like nanocrystal of obtained hard carbon influences the sodium ion diffusion ability, thereby affecting the rate performance. Our work offers a simple and eco-friendly way for converting biomass to highly capacity carbon as well as a towardly anode material for sodium-ion batteries, which will open up new avenues of other biomass carbon materials with promising applications.

Surface N modified 2D g-C3N4 nanosheets derived from DMF for photocatalytic H2 evolution

The two-dimensional graphitic carbon nitride (2D g-C3N4) shows excellent photocatalytic performance due to its graphene-like structure, unique electronic and optical property. However, the 2D g-C3N4 suffers from lower visible light utilization because of the quantum size effect. Herein, a new approach was developed to prepare the surface nitrogen modified 2D g-C3N4 nanosheets (NCNS) through a facile hydrothermal treatment route. The as-obtained NCNS exhibited a high hydrogen evolution rate of 19.8 mmol h−1 g−1 with a turnover number (TON) of 642.39 in 5 h, and the external quantum efficiency (EQE) of 10.7% at 420 nm was superior to the g-C3N4 different morphological regulation. The surface nitrogen modification prompted electron delocalization of two-dimensional electron system, leading to accelerating photon-generated carrier separation and transportation efficiency.

Hierarchical growth of ZnO nanorods over SnO2 seed layer: insights into electronic properties from photocatalytic activity

The ZnO–SnO2 heterojunction catalyst was prepared via a hydrothermal treatment route. The heterojunction exhibited a superior photocatalytic performance in comparison to SnO2 and ZnO, attributed to the good charge separation.

Tailoring the surface characteristic of alumina for preparation of highly active NiMo/Al2O3 hydrodesulfurization catalyst

Tailoring alumina surface via hydrothermal treatment route was investigated so as to design highly active NiMo/Al2O3 hydrodesulfurization catalysts. First, two types of tailored γ-Al2O3 supports were prepared from hydrothermally treated pseudo-boemhite or hydrothermally treated γ-Al2O3, respectively. The characterization results showed that compared with reference γ-Al2O3, the tailored γ-Al2O3 supports have a notable increase in their crystallite size, terminal hydroxyl groups and the ratio of Al(tetrahedral)/Al(octahedral), but an obvious decrease in surface area, pore volume, and the amount of hydroxyl groups and tetrahedral cation vacancies. Metal species supported on the tailored γ-Al2O3 supports are easier to be reduced or sulfided. And for the sulfided catalysts, the average slab length and stacking number of (Ni)MoS2 obviously increase with the crystallite growth of the corresponding γ-Al2O3 supports. NiMo supported on the tailored γ-Al2O3 support obtained from hydrothermally treated pseudo-boehmite, exhibits the highest hydrodesulfurization activity for 4,6-DMDBT. It can be ascribed to its moderately crystallized particles, proper decrease in the amount of hydroxyl groups and tetrahedral cation vacancies, and more well-dispersed Ni–Mo–S active phases.

Pore morphology-controlled preparation of ZrO2-based hybrid catalysts functionalized by both organosilica moieties and Keggin-type heteropoly acid for the synthesis of levulinate esters

A series of ZrO2-based hybrid catalysts functionalized by both organosilica groups and Keggin type heteropolyacid, H3PW12O40/ZrO2–Si(Et/Ph)Si and H3PW12O40/ZrO2–Si(Ph), with different structural orderings and pore geometries were controllably prepared by a one-pot template-assisted sol–gel co-condensation–hydrothermal treatment route. The pore morphologies, textural properties and acidity of as-prepared hybrid catalysts were characterized by XRD, TEM, nitrogen gas porosimetry, in situ pyridine-FTIR spectroscopy and titration, while the structural integrity of the incorporated functionalities was studied by FT-IR, 31P MAS NMR, 13C CP-MAS NMR and 29Si MAS NMR. As the novel solid acid catalysts, the catalytic performance of as-prepared materials was evaluated by esterification of levulinic acid with various alcohols under mild conditions. Meanwhile, comparative studies were carried out to find out the influences of acidity, porosity and surface hydrophobicity on the catalytic activity of the catalysts. Finally, the recyclability of the catalysts was tested.

Synthesis and characterization of Sn or Al-containing SBA-15 mesoporous materials without mineral acids added

A simple and direct-synthesis route without mineral acids added was successfully developed to prepare Sn or Al-containing SBA-15 mesoporous materials with good mesostructural ordering, high surface area and narrow pore-size distribution via evaporation-induced self-assembly (EISA) process in which no mineral acids were added and no hydrothermal treatment was needed. Compared with other direct-synthesis methods of metal ions substituted SBA-15 materials reported early, our synthesis method, with two unique points of no mineral acid and hydrothermal treatment route, is very simple, efficient and energy-saving. These materials were characterized by powder X-ray diffraction (XRD), N 2 sorption isotherms, TEM with EDS analysis, 27Al MAS NMR, and UV–visible absorption spectra.