Hydrothermal Reaction Conditions Research Articles

One-step hydrothermal synthesis of iron phosphate dihydrate with ferric salt dephosphorized sludge

This study presents a novel approach for one-step hydrothermal synthesis of iron phosphate dihydrate (FePO4·2H2O) using ferric salt dephosphorization sludge (FePs) from liquor wastewater. The gradual dissolution of FePs, facilitated by increasing temperatures and concentrations of phosphoric acid, releases Fe3+ and PO43- ions during hydrothermal reactions. These ions recrystallize into iron phosphate dihydrate and iron hydroxy-phosphate (Fe5(PO4)4(OH)3·2H2O) depending on the conditions. Through a single-factor experiment, the effects of total organic carbon (TOC) in FePs and hydrothermal reaction conditions on the phase and morphology of the products were investigated, then the recrystallization process of iron phosphate dihydrate was also simulated by molecular dynamics. The first charge/discharge capacities of lithium iron phosphate (LFP) batteries synthesized from the optimal products were 153.1 and 149.4 mAh·g-1 at 0.1C rate, respectively, and the cycling performance could be maintained under different rates, which has a good application prospect. The reaction fully utilized the iron and phosphorus resources in FePs, and the filtrate could be recycled to avoid the waste of resources, which provided a new idea for the resource utilization of FePs.

Enhanced oxygen evolution reaction by controlled assembly of Co3O4 nanorods on TiB2 nanosheets

Cobalt oxide (CO) and Titanium boride hybrid composites are synthesized via hydrothermal reaction conditions followed by attentive calcination. Exfoliated Titanium boride (ETB) nanosheet templates are used for the first time to skillfully decorate CO nanorods on it. As-synthesized diverse hybrid composites ETB@CO (1, 3, and 5) are optimized for the electrochemical properties and weight ratios of CO and ETB nanosheets altered accordingly. Various spectroscopic techniques are used to characterize the as-synthesized hybrid composite materials. Standard electrochemical techniques such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and Chronopotentiometry (CP) are used to discover the electro-catalytic behavior of hybrid composites. The composite ETB@CO-3 recorded outstanding performance by exhibiting a lower overpotential of 271 mV, with a cramped Tafel slope of 42.4 mV dec−1 for electrochemical oxygen evolution reaction (OER). The composite ETB@CO-3 clamour a lower overpotential of 271 mV to attain the current density of 10 mA/cm2 than the other composite ratio. Furthermore, the composite ETB@CO-3 displayed remarkable stability over 24 h with continuous OER reaction by maintaining stable voltage at 10 mA/cm2 current density and exhibited no noticeable increase in overpotential, suggesting its feasibility in practical applications.

Low over-potential cathode synthesized using a binary metal self-templated molybdenum reinforced method for highly efficient hydrogen evolution

To solve the problem of renewable energy generation fluctuation, water splitting for hydrogen generation is proposed, which can store renewable energy as hydrogen energy. Low overpotential cathode materials can effectively reduce the cost of hydrogen production. Here, a new NiMo/NMF electrode was prepared using a hydrothermal coupled H2 reduction method. Three-dimensional NiMo nanorod arrays were constructed by modulating the ion dissolution and surface epitaxial growth process of the electrode substrate. The influence of different hydrothermal reaction and H2 reduction conditions on the electrochemical performance of the electrode was investigated. Under optimum preparation conditions, the NiMo/NMF electrode exhibits a extremely low overpotentials of 158 mV at 500 mA cm-2 (30% wt. KOH alkaline medium), which can serve for preparing high efficiency and economy electrodes by in-situ integration of high active components on metal foam substrate. The NiMo/NMF electrode is a high-performance electrocatalytic cathode material with great prospects for industrial applications.

Hydrothermal Synthesis, Phase Analysis, and Magneto-Electronic Characterizations of Lead-Free Ferroelectric BM2+(Zn, Ca, Mg)T-BFO System.

In this study, lead-free BiM2+(Zn, Ca, Mg)Ti-BiFeO3 ceramics are fabricated under eco-friendly hydrothermal reaction conditions at 250 °C. XRD patterns show that all the synthesized compounds exhibit a phase coexistence of monoclinic and tetragonal perovskite-type structures with a morphotropic phase boundary at x = 0.4, with minimum impurity. The calculated average crystallite/grain size of the samples was close to 50 nm at full width at half-maximum of the main peak. The corresponding bonds of the constituent elements were observed by FTIR analysis, which further supports the formation of the local structure. EDS analyses detect all of the elements, their quantities, and compositional homogeneity. SEM data show agglomerated and nearly spherical morphology with an average particle size of about 128 nm. All synthesized ceramic powders revealed thermal stability with trivial mass loss up to investigated high temperatures (1000 οC). The dielectric constant reached its maximum at 38.7 MHz and finally remained constant after 80 MHz for all nanoceramics. Because of the complementary impact of different compositions, the most effective piezoelectric characteristics of d33 = 136 pCN-1, Pr = 8.6 pCN-1 cm-2, and kp = 11% at 30 °C were attained at x = 0.4 content for 0.4BiCaTi-0.6BiFeO3 ceramic. The measured magnetic hysteresis data (M-H curve) showed a weak ferromagnetic nature with the highest moment of ∼0.23 emu/g for 0.4BiCaTi-0.6BiFeO3, and other samples exhibited negligible ferromagnetic to diamagnetic transition. The optical response study shows that the 0.4BiMgTi-0.6BiFeO3 sample yielded the maximal transmittance (50%), whereas the 0.4BiCaTi-0.6BiFeO3 compound exhibited the highest refractive index. The calculated large band gap shows a high insulating or dielectric nature. Our findings demonstrate that the BiM2+Ti-BiFeO3 system, which was fabricated using a low-temperature hydrothermal technique, is an excellent lead-free piezoelectric and multiferroic nanoceramic.

Preparation and Ferroelectric Properties of Er Doped BaTiO3 Nanotubes

In this paper, erbium-doped barium titanate nanotubes with different concentrations were prepared by combining the anodic oxidation method with the low-temperature hydrothermal method. The TiO2 nanotubes produced by electrolysis using titanium flakes as substrate were put into barium hydroxide octahydrate solution for hydrothermal reaction, and different concentrations of Er-doped barium titanate nanotubes were prepared by adding different concentrations of Er(NO3)3·5H2O to the reaction solution. The samples with different doping concentrations were analyzed for their morphological structure, physical phase composition and ferroelectric properties. All samples were found to have complete barium titanate nanotube structure, and the diffraction peaks of XRD were compared with the standard Cope, and the doped samples were all tetragonal phase chalcogenide structure with no other impurities generated. From the hysteresis loop diagram of the samples measured by the TF-2000 ferroelectric analyzer, it can be found that the residual polarization intensity of the samples showed a characteristic of increasing and then decreasing with the increase of the doping concentration, and the residual polarization intensity was the largest at 0.151 uC/cm2 under the hydrothermal reaction condition of 180°C and 3 h with the Er3+ concentration of 0.0025 mol/L.

Hydrochloric Acid Catalyzed Hydrothermal Treatment to Recover Phosphorus from Municipal Sludge

Resource utilization of sludge is critical because traditional sludge treatment methods cause a large amount of nutrient loss. This study investigated the impact of hydrochloric acid quantity, reaction temperature, and time on phosphorus release and migration from municipal sludge during hydrothermal treatment and designed a sludge disposal method for the recovery and utilization of phosphorus resources. We know that hydrochloric acid destroys the complexation of calcium and phosphorus precipitates, leading to the selective transfer of phosphorus to the liquid phase, and that the addition of 1–5% hydrochloric acid corresponds to a phosphorus extraction rate in the range of 0.3–98%. When hydrochloric acid is added, a change in temperature and reaction time has a negligible effect on phosphorus. Phosphorus can be recovered using the liquid product obtained under the optimal hydrothermal reaction conditions (adding 5% HCl at 205 °C for 30 min). After adjusting the pH value and adding the magnesium source, struvite (MgNH4PO4·6H2O) can be precipitated quickly and with high purity. At a cost of USD 27.8/ton of sludge, this method can recover 94% of the phosphorus in the sludge, and the bioavailable phosphorus ratio of the product is 93%, therefore, providing an important alternative to existing phosphorus recovery technologies.

Hybrid bimetallic phosphonates as cathode materials for miniaturized in-plane asymmetric supercapacitor device

The utilization of wearable electronic devices facilitates the development of smart and flexible technology as a superior energy storage device that minimizes the dimension of wearable devices. The simple vacuum filtration method was employed to fabricate the micro-supercapacitor device (MSC) using the as-synthesized bimetallic nickel cobalt phosphonate (NiCoNPO) on the PVDF membrane as substrate. Novel microporous bimetallic metal phosphonates (NiCoNPO, Ni2CoNPO, NiCo2NPO) have been synthesized in a hydrothermal reaction condition by varying the molar ratio (Ni1:Co1; Ni2:Co1; Ni1:Co2) of metal sources without any employment of templating agent. Among these, NiCoNPO exhibits the remarkable specific capacitance of 2308 F g−1 at 1 mV s−1 and long-term cyclic stability up to the 5000th cycle with 99.6 % capacity retention in the three-electrode system. In addition, the electrode material demonstrates an exceptional capacitance of 574 F g−1 with stability (87.6 % retention) in a two-electrode system. Also, it displays excellent performance as a flexible MSC device with an areal capacitance of 123.5 mF cm−2. Notably, the MSC demonstrates long-term stability up to the 5000th cycle with a capacity retention of 85.6 %, suggesting the electrode material has excellent mechanical flexibility and superior electrochemical performance.

Valorizing natural-abundant glucose to lactic acid using a MOF-808 catalyst under green hydrothermal conditions.

Highly robust Zr-based MOF-808, featuring Lewis acid Zr sites and coordinate hydroxide ions upon the removal of the monocarboxylate capping reagent, emerges as an efficient catalyst for the hydrothermal conversion of glucose into lactic acid. A remarkable 99% glucose conversion with an impressive 76.6% yield of lactic acid can be achieved. The large pore window of MOF-808 facilitates the diffusion of glucose to the active sites within the framework. The single-site attribute of the catalytic center enables a high selectivity of lactic acid over the competitive product, 5-(hydroxymethyl)furfural, under hydrothermal reaction conditions.

Tuning scintillation property of CsLu2F7: Pr crystals for X-ray imaging

Lanthanide doped fluoride scintillators possess a diverse range of applications in the fields of computed tomography and medical imaging. In this study, CsLu2F7: Pr crystals have been synthesized by a simple hydrothermal method to realize X-ray excited optical luminescence (XEOL). Our results reveal that the reaction temperature and amount of cetyltrimethylammonium bromide (CTAB) can significantly change the morphology of the crystals; the suitable hydrothermal reaction conditions, the amount of CTAB, and the doping concentration of Pr3+ ions are favorable for the enhancement of the XEOL intensity; and the crystals exhibit good irradiation stability under prolonged X-ray excitation. In addition, we used the crystal to prepare scintillation films to realize XEOL imaging. This research provides crucial information to support an in-depth investigation into the XEOL performances of CsLu2F7 doped with lanthanide ions.

Mechanochemistry of Strecker degradation: Interaction of glyoxal with amino acids

Mechanochemistry is rapidly evolving into a versatile and green method for chemical synthesis. Due to its unique reaction conditions, ball milling of sugars and amino acids mainly leads to the formation of Amadori products with minimum degradation. In this study, we milled glyoxal trimer dihydrate with twenty proteogenic amino acids to demonstrate the formation of Strecker degradation products. HS-GC/MS studies indicated that Strecker degradation proceeded to selectively generate Strecker aldehyde and unsubstituted pyrazine as the major volatiles. Moreover, ESI/qToF/MS studies demonstrated for the first time the formation of the proposed key Strecker degradation intermediates, such as the condensation products and their decarboxylated products, indicating the similarity of the mechanism of Strecker reaction under ball milling to that proposed under hydrothermal reaction conditions. These studies provided supporting evidence that ball milling at ambient temperatures could be used as a novel synthetic approach to prepare precursors of aroma-active volatiles through Strecker degradation.

Sol-hydrothermal synthesis of Na0.5Bi0.5TiO3 powders and corresponding ceramics prepared by traditional and flash sintering

In this paper, a new wet chemical route named sol-hydrothermal method was used to synthesize Na0.5Bi0.5TiO3 (NBT) nanopowders. The effects of hydrothermal reaction conditions such as temperature, time and NaOH concentration on the properties of the powder were studied in detail. The results showed that as-synthesized NBT powders with were perovskite structure with rhombohedral symmetry and had submicron size (200 nm ∼ 800 nm). The morphology of NBT powders was mainly spherical and they had good dispersibility. NBT powders with homogeneous size and pure phase were synthesized under the optimum condition of hydrothermal reaction at 200 °C for 24 h. It is worth noting that pure NBT ceramic could not be obtained by traditional sintering at 1100 °C for 2 h. However, the relatviely dense ceramic with a relative density of 95.8% and an apparent porosity of 1.8% was obtained by electric field assisted flash sintering for only 3 s at 700 °C. Therefore, the very short time flash sintering method was suitable for the preparation of volatile NBT ceramic. In particular, a mechanism named Electric Field Assisted Solid Crystal Growth (EFASCG) was proposed to explain sintering process.

Review of the Booklet : Solvothermal and Hydrothermal Techniques for Nano-synthesis: An Overview by Dr. Manisha Bora

Dr.Manisha Bora has come with handy booklet on hermal and Hydrothermal Techniques for Nano- in the same timeframe of October 2023 when Nobel prize in Chemistry has been awarded to three American Professors Bawendi, Brus and Yekimov for their pioneering research on Q Dots, the tiniest components of nanotechnology. What a great coincidence! This booklet is thus a timely and welcome addition in the sphere of nanotechnology. It comprises in all 12 chapters followed by apt references at the end. Illustrative figures and synthesis equations are provided at appropriate places. Table-1 furnishes summary of hydrothermal and solvothermal reaction conditions for the synthesis of typical nanomaterials and their focussed end-applications. It is well established that hydrothermal/solvothermal synthesis conditions lead to formation of nanostructures with complex morphological features/ hierarchical nano- architecture which, in turn, can enhance the utility of the envisaged end-application. Perhaps, inclusion of representative FESEM and FETEM images in this booklet could have been very useful for clarity on nano-scale formation and also to prove the merits of hydrothermal/solvothermal

Superior catalytic performance of Zr-incorporated MnCu/SBA-15 catalyst for low-temperature NH3-SCR of NO: Effect of support

High surface area mesoporous solid support has attracted much interest in the development of cost-effective catalysts for NOx abatement at low temperatures. SBA-15, a high surface area mesoporous material, was employed in the preparation of Al, Ti, and Zr incorporated SBA-15 through a direct synthesis approach under long hydrothermal reaction conditions (100 °C for 72 h). Heteroatom incorporation facilitated change in the morphology and textural properties of the material and was applied as a catalytic supports in order to facilitate the development of a MnCu bimetallic catalyst by a facile conventional co-impregnation method. At temperatures as low as 260 °C, the catalyst that was developed displayed superior deNOx activity for SCR of NO with NH3. There have been various physicochemical studies undertaken on the catalysts that were prepared, such as XRD, XPS, BET, HR-SEM, and HR-TEM. The deNOx optimization and deNOx activity over the catalysts are discussed. The exceptional deNOx activity at low temperatures may be attributed to the rod-like morphology, extensive oxygen vacancies, and high ratio of Mn3+ + Mn4+/Mn on 10Mn4Cu/Zr-SBA-15 catalyst. Furthermore, the catalyst also displayed a synergetic interaction between the Mn and the Zr species on its surface, which contributed to the catalyst's superior catalytic recycle ability and its long-term stability on stream stability. A useful approach of preparation is provided in order to accomplish the industrial use of a bimetallic catalyst consisting of manganese and copper at a low cost.

The Cobalt(II) Oxidotellurate(IV) Hydroxides Co2(TeO3)(OH)2 and Co15(TeO3)14(OH)2

Previously unknown Co2(TeO3)(OH)2 and Co15(TeO3)14(OH)2 were obtained under mild hydrothermal reaction conditions (210 °C, autogenous pressure) from alkaline solutions. Their crystal structures were determined from single-crystal X-ray diffraction data. Co2(TeO3)(OH)2 (Z = 2, P1¯, a = 5.8898(5), b = 5.9508(5), c = 6.8168(5) Å, α = 101.539(2), β = 100.036(2), γ = 104.347(2)°, 2120 independent reflections, 79 parameters, R[F2 > 2σ(F2)] = 0.017) crystallizes in a unique structure comprised of undulating 2∝[Co2(OH)6/3O3/3O2/2O1/1]4− layers. Adjacent layers are linked by TeIV atoms along the [001] stacking direction. Co2(TeO3)(OH)2 is stable up to 450 °C and decomposes under the release of water into Co6Te5O16 and CoO. Magnetic measurements of Co2(TeO3)(OH)2 showed antiferromagnetic ordering at ≈ 70 K. The crystal structure of Co15(TeO3)14(OH)2 (Z = 3, R3¯, a = 11.6453(2), c = 27.3540(5) Å, 3476 independent reflections, 112 parameters, R[F2 > 2σ(F2)] = 0.026) is isotypic with Co15(TeO3)14F2. A quantitative structural comparison revealed that the main structural difference between the two phases is connected with the replacement of F by OH, whereas the remaining part of the three-periodic network defined by [CoO6], [CoO5(OH)], [CoO5] and [TeO3] polyhedra is nearly unaffected. Consequently, the magnetic properties of the two phases are similar, namely being antiferromagnetic at low temperatures.

Controllable synthesis and formation mechanism of pure and Fe-doped h-MoO3 microrods under hydrothermal reaction conditions

In the present work, pure and Fe-doped h-MoO3 microrods were successfully synthesized via the hydrothermal method using (NH4)6Mo7O24·4H2O and concentrated HNO3 as the raw materials.

Isostructural Family of Rare‐Earth MOFs Synthesized from 1,1,2,2‐Tetrakis(4‐phosphonophenyl)ethylene

AbstractThe tetraphosphonic acid 1,1,2,2‐tetrakis(4‐phosphonophenyl)ethylene (H8L) was used as linker in the synthesis of eight new isostructural, phosphonate‐based metal‐organic frameworks of composition [M2(H2O)2(H2L)] ⋅ xH2O (M=Y3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+; 1.5<x<4), denoted as M‐CAU‐34. The compounds were synthesized under hydrothermal reaction conditions, using the corresponding metal nitrates as starting materials. The determination of the crystal structure was achieved by a combination of electron and powder X‐ray diffraction (PXRD) data. In addition, a thorough characterization by thermogravimetric and elemental analysis, IR‐ and Raman‐spectroscopy as well as H2O‐sorption is given.

Synthesis of a Self‐assembled Dual Morphologies Ag‐NPs/SrMoO4 Photocatalyst with LSPR Effect for the Degradation of Methylene Blue Dye

AbstractMorphology of photocatalyst has attracted many attentions due to its significant effect on photocatalytic properties. Herein, the effects of hydrothermal reaction conditions including time, temperature, and pH value on the morphology evolution as well as on the photocatalytic performance of SrMoO4 were investigated in detail. It was found that SrMoO4 had self‐assembled dual morphologies (spherical and dumbbell shape) under the specific reaction conditions with time=24 h, temperature=200 °C, and pH=6.13. In order to enhance its photocatalysis further, the silver nanoparticles (Ag‐NPs) were well‐dispersed uniform on the surface of as‐prepared samples to obtain Ag‐NPs/SrMoO4 composites by photoreduction method. It was determined that 3 %Ag‐NPs/SrMoO4 had the first‐class photocatalytic performance (η=83.7 %, kapp=0.05229 min‐1) for the photodegradation of MB dye, which is ∼2.52 times that of the bare SrMoO4 with dual morphology (η=51.9 %, kapp=0.02078 min−1) by comparison with the apparent first‐order reaction rate constants. The photocatalytic performance was promoted by high efficiency of photo‐induced carriers’ separation based on the effect of Localized Surface Plasmon Resonance (LSPR) of well‐dispersed Ag‐NPs.

Rational control on the morphology of WS2 nanomaterials by altering hydrothermal reaction conditions

Here, we present the synthesis of nanomaterials based on WS2, using a simple and green hydrothermal route. The synthesis was accomplished by the high-temperature hydrothermal reaction of WS2 powder in aqueous NaOH. Upon changing the mole ratio of WS2 to NaOH, different types of nanomaterials such as quantum dots (QDs), nanosheets and hybrid QDs-nanosheets were obtained. We systematically characterized the optical properties of these materials. All exhibited high photoluminescence spanning a large portion of the UV and visible region of the electromagnetic spectrum. The morphological and other structural aspects were unraveled by transmission electron microscopy (TEM) and Raman spectroscopy. Size-dependent photophysical properties of various WS2 nanomaterials were investigated using UV–visible absorption spectroscopy, fluorescent spectroscopy and fluorescence lifetime analysis. We envisage that these materials can be promising candidates for various biological and optoelectronic applications due to their extraordinary temporal and photostability.

Semiconductive MOFs with tetranuclear Co-clusters constructed from 2,5-dimethoxyterephthalic acid and phenyl imidazole ligands

Complexes {[Co2(DTA)2(1,4-BMIB)(H2O)]·1·.5H2O}n(ZNC-9) and {[Co2 (DTA)1.5(OH)(TIB)]·5H2O}n (ZNC-10) (H2DTA = 2,5-dimethoxyterephthalic acid, 1,4-BMIB = 1,4-bis(2-methyl-1H-imidazol-1-yl)benzene, TIB = 1,3,5-tri(1H- imidazol-1-yl)benzene) were obtained via hydrothermal reaction condition. DTA2− ligands adopted various coordination modes to result in tetranuclear clusters [Co4(CO2)8(μ2-H2O)2] and [Co4(μ3-OH)2]6+ in ZNC-9 and ZNC-10, respectively. In complex ZNC-9, [Co4(CO2)8(μ2-H2O)2] as 10-connected node was bridged by DTA2− and 1,4-BMIB to form a 3D framework with Schlafli symbol of (36.434.62). In complex ZNC-10, DTA2− ligands and [Co4(μ3-OH)2]2+ built a 4-connected dia net, while TIB and [Co4(μ3-OH)2] units built a 3,6-connected ant net. The dia and ant nets further constructed a (3,10)-connected framework with point symbol (3.42)2(34.410.512.613.76). Additionally, UV–vis spectra and electrochemical tests have confirmed that ZNC-9 and ZNC-10 belong to n-type semiconductors possessing low resistance for charge transportation. In photo-catalytic experiments, ZNC-9 and ZNC-10 have obvious catalytic activity in degradation of dye under ultraviolet light.

Synchronous Moderate Oxidation and Adsorption on the Surface of γ-MnO2 for Efficient Iodide Removal from Water.

Long-term exposure to excessive iodine via drinking water presents health risks. Moderate oxidation of iodide (I-) to iodine (I2) has a better iodine removal effect than excessive oxidation to iodate (IO3-). This study combines computational and experimental methods to construct a heterogeneous interface with synchronous I- moderate oxidation and I2 adsorption to increase the total iodine removal. Compared to other forms of crystal manganese dioxide (MnO2), theoretical calculations predict that MnO2 with a γ-crystal structure has the lowest adsorption energy, that is, -1.20 eV, and a slight overlap between the conduction and valence bands, which favors electron transfer between I- and Mn(IV) and I2 adsorption. Thus, γ-type MnO2 was designed by adjusting the precursor Mn sources and hydrothermal reaction conditions. The liquid chromatography-inductively coupled plasma-mass spectrometry and high-performance liquid chromatography confirmed that the total iodine concentration in water decreased from 173.7 to 36.3 μg/L after 2 h, with 200 mg/L γ-MnO2 dosage lower than the national standard of 0.1 mg/L. A minute proportion of I- in water was converted to IO3- (approximately 1.1 μg/L). The current I- adsorbent performed better than previously reported ones. During iodine removal, most of the I- migrated from water to the surface of γ-MnO2, and the ratio of I- to I2 was determined to be 1:0.6 by X-ray photoelectron spectroscopy. This study evaluates iodine species transformation and an optimum strategy for heterogeneous interface design; it is promising for treating high-iodine groundwater.