Solvothermal System Research Articles

Spherical Fe3O4 morphology modulation for enhancing infrared emissivity and radiant heat dissipation

Radiant heat dissipation has emerged as a critical technique for effective thermal management, offering energy efficiency, cost-effectiveness, and adaptability to various shapes while promoting environmental sustainability. However, the intricate relationship between material structures and emissivity remains inadequately understood. This study primarily utilizes a straightforward and economical solvothermal method to regulate the synthesis of Fe3O4 ferrite, exploring its structural relationship with infrared radiation performance. By adjusting the solvent ratio of ethylene glycol and diethylene glycol in the solvothermal system, we successfully synthesized uniformly dispersed Fe3O4 nanospheres ranging from 10 to 800 nm. Notably, our research revealed a positive correlation between infrared emissivity and the particle size. Submicron hollow spheres with a size of 800 nm exhibit an exceptionally high emissivity of 0.992 within the 8–13 μm wavelength range. Morphological and size variations induced alterations in lattice strain, oxygen vacancies, and phonon lifetimes, which consequently influencing the lattice vibration absorption and infrared emissivity. Moreover, the device surface with a composite coating formed by combining 15 wt% Fe3O4 particles with organic matter, achieves a temperature difference of 17.6 °C under a 4 W input power condition compared to blank device. This finding contributes to further revealing the process of material radiative heat dissipation, driving the application of high-emissivity materials for heat dissipation in high-power electronic devices.

Synthesis of Monodispersed Pd Nanoparticles and Ultrathin Twisty Pd Nanowire Networks for Electrooxidation of Ethanol.

In recent years, preparing precious metal catalysts with a controllable morphology has become a hot research topic for researchers. In this study, monodispersed palladium (Pd) nanoparticles (NP) and ultrathin Pd twisty nanowire networks (TNN) were synthesized in a solvothermal system using N,N-dimethylformamide (DMF) and oleylamine (OAm) as solvents, Transmission electron microscopy (TEM) images reveal the successful synthesis of nanoparticles and ultrathin TNN microstructures. Electrochemical data show that the current densities of Pd-NP and Pd-TNN for the ethanol oxidation reaction (EOR) reach 1878 mA mg-1 and 1765 mA mg-1, respectively. Compared to commercial Pd/C, Pd-TNN and Pd-NP exhibit better catalytic stability, lower electron transfer barriers, and more resistance to catalyst poisoning. Temperature, pH value, and ethanol concentration are all favorable for the EOR. According to the experimental data, the mechanism of enhanced electrocatalytic activity of Pd-NP and Pd-TNN catalysts for ethanol oxidation is discussed. This paper presents a method for preparing catalysts with stabilized structures to develop Pd-based catalysts for electrocatalytic oxidation reactions.

Modulating Ni-S coordination in Ni3S2 to promote electrocatalytic oxidation of 5-hydroxymethylfurfural at ampere-level current density.

Electricity-driven oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a highly attractive strategy for biomass transformation. However, achieving industrial-grade current densities remains a great challenge. Herein, by modulating the water content in a solvothermal system, Ni3S2/NF with stabilized and shorter Ni-S bonds as well as a tunable coordination environment of Ni sites was fabricated. The prepared Ni3S2/NF was highly efficient for electrocatalytic oxidation of HMF to produce FDCA, and the FDCA yield and Faraday efficiency could reach 98.8% and 97.6% at the HMF complete conversion. More importantly, an industrial-grade current density of 1000 mA cm-2 could be achieved at a potential of only 1.45 V vs. RHE for HMFOR and the current density could exceed 500 mA cm-2 with other bio-based compounds as the reactants. The excellent performance of Ni3S2/NF originated from the shorter Ni-S bonds and its better electrochemical properties, which significantly promoted the dehydrogenation step of oxidizing HMF. Besides, the gram-scale FDCA production could be realized on Ni3S2/NF in a MEA reactor. This work provides a robust electrocatalyst with high potential for practical applications for the electrocatalytic oxidation of biomass-derived compounds.

A High-Throughput Preparation Strategy for Microporous Polyimides and Their Photocatalysis Performance: Understanding Polymerization Kinetics and Thermodynamics in a Solvothermal System

A High-Throughput Preparation Strategy for Microporous Polyimides and Their Photocatalysis Performance: Understanding Polymerization Kinetics and Thermodynamics in a Solvothermal System

Solvothermally Synthesized Hierarchical Aggregates of Anatase TiO2 Nanoribbons/Nanosheets and Their Photocatalytic–Photocurrent Activities

Hierarchical aggregates of anatase TiO2 nanoribbons/nanosheets (TiO2-NR) and anatase TiO2 nanoparticles (TiO2-NP) were produced through a one-step solvothermal reaction using acetic acid or ethanol and titanium isopropoxide as solvothermal reaction systems. The crystalline structure, crystalline phase, and morphologies of synthesized materials were characterized using several techniques. According to our findings, both TiO2-NR and TiO2-NP were found to have polycrystalline structures, with pure anatase phases. TiO2-NR has a three-dimensional hierarchical structure made up of aggregates of TiO2 nanoribbons/nanosheets, while TiO2-NP has a nanoparticulate structure. The photocatalytic and photocurrent activities for TiO2-NR and TiO2-NP were investigated and compared with the widely used commercial TiO2 (P25), which consists of anatase/rutile TiO2 nanoparticles, as a reference material. Our findings showed that TiO2-NR has higher photocatalytic and photocurrent performance than TiO2-NP, which are both, in turn, higher than those of P25. Our developed solvothermal method was shown to produce a pure anatase TiO2 phase for both synthesized structures, without using any surfactants or any other assisted templates. This developed solvothermal approach, and its anatase TiO2 nanostructure output, has promising potential for a wide range of energy harvesting applications, such as water pollution treatment and solar cells.

Synthesis of Urchin-like Ni@NP@NCP Composites with Three Solvothermal Systems for Highly Efficient Overall Seawater Splitting.

In this work, an urchin-like Ni@Ni2P@NiCoP (Ni@NP@NCP) composite was prepared on nickel foam by a simple hydrothermal treatment process. Using the prepared NiO nanosheets as templates, the NiCo precursor was prepared in the presence of three solvothermal systems of water/dimethylformamide (DMF)/dimethyl sulfoxide (DMSO) by the hydrothermal process. After mixing and calcining with sodium hypophosphite under a nitrogen atmosphere at a high temperature for phosphating, an urchin-like Ni@NP@NCP(F/SO/H) nanostructured catalyst was obtained with superior hydrogen evolution and oxygen evolution performance. To further explore their efficiency in seawater splitting. Ni@NP@NCP(F/SO/H) composites were used as the cathode and anode of an electrolytic cell, which delivered 1.822 V potential at 300 mA cm-2 in simulated seawater (1 M KOH and 0.5 M NaCl). This may provide an effective way of developing clean energy.

Copper-induced formation of heterostructured Co3O4/CuO hollow nanospheres towards greatly enhanced lithium storage performance

We report a facile template-free fabrication of heterostructured Co3O4/CuO hollow nanospheres using pre-synthesized Co/Cu-glycerate as conformal precursor. The introduction of copper nitrate in the solvothermal reaction system of glycerol/isopropanol/cobalt nitrate readily induces the conversion from solid Co-glycerate to hollow Co/Cu-glycerate nanospheres, and the effect of the Co/Cu atomic ratio on the structure evolution of the metal glycerates as well as their corresponding oxides were investigated. When examined as anode materials for lithium-ion batteries, the well-defined Co3O4/CuO hollow nanospheres with Co/Cu molar ratio of 2.0 demonstrate excellent lithium storage performance, delivering a high reversible capacity of 930 mAh/g after 300 cycles at a current density of 0.5 A/g and a stable capacity of 650 mAh/g after 500 cycles even at a higher current density of 2.0 A/g, which are much better than their counterparts of bare CuO and Co3O4. The enhanced lithium storage performance can be attributed to the synergistic effect of the CuO and Co3O4 heterostructure with hollow spherical morphology, which greatly enhances the charge/electrolyte transfer and effectively buffers the volume changes upon lithiation/delithiation cycling.

Synthesis, Structure, and Magnetic Properties of Two {Co16IICo4III} Supertetrahedral T4 Clusters Formed from the In Situ Dissociation of a Tertiary N-Containing Ligand

Two mixed-valent cobalt clusters {[(CoII)16(CoIII)4(μ6-O)4(μ3-OH)12(OCH3)12(H2O)8(BMBC)4]·(NO3)8} (1) and {[(CoII)16(CoIII)4(μ3-OH)20(OCH2CH3)4(HOCH2CH3)8(BMBC)4]·(NO3)8} (2) were synthesized and constructed by a semiflexible dicarboxylic ligand 4′,4′-[ammoniobis(methylene)]-bis[(1,1′-biphenyl)-2-carboxylate] (BMBC–) with Co(NO3)2·6H2O under solvothermal systems. Interestingly, the ligand BMBC- is afforded from the in situ dissociation reaction of tertiary N-containing organic carboxylic acid ligands. The complexes present a beautiful supertetrahedral T4 cluster formed by an interior Co4IIIO4 cubane and four exterior Co4IIO4 cubanes bridged via μ6-O2 and μ3-OH– ions and stabilized by four BMBC– organic ligands. The complexes were confirmed by single-crystal X-ray diffraction (XRD), elemental analysis, infrared spectroscopy, and thermogravimetric analysis. Furthermore, the magnetic analyses reveal that the [Co20] cluster exhibits an antiferromagnetic behavior.

Preparation and characterization of oriented hydroxyapatite bundles in supersaturated solution: ionic interference and charge balance

Hydroxyapatite (HA), an artificial bioceramic with high similarity to the mineral constituent of vertebrate bones and teeth, has attracted extensive attention due to its excellent bioactivity and biocompatibility. The micro-nano structure of HA is a vital factor in expanding its application in biomedicine as well as in many other industrial fields. What's more, HA nanofiber exhibits outstanding properties among its various morphologies. In this work, HA bundles with the same oriented nanofibers are successfully synthesized in a solvothermal reaction system by controlling the amount of carbonate addition and using oleic acid as a template. Under the synergistic effect of different molar ratios of hydroxide ion to carbanion ([OH−]/[CO32−]), HA nanofibers gradually increase their aspect ratio and tend to grow into oriented bundles. This product has admirable flexibility and good mechanical strength, as well as great application potential. Based on the characterization and analysis results, we take a further exploration of the effects of ionic interference ([OH−]/[CO32−]) and charge balance (CO32− vs PO43, Na + vs Ca2+) on the microstructure, phase composition and thermal stability of HA nanofibers bundles (HANBs) in the solvothermal system during the chemical reaction process. And then, the formation and assembly mechanism of HANBs is proposed, and the role of van der Waals forces in this process is also discussed. Furthermore, the generation of this clustered state may be influenced by the shift in the dissolution equilibrium of insoluble carbonates during synthesis. This research provides a new direction for controlling the micro-nano morphology of HA to further obtain products with desirable properties.

Transition Metal-Doped Boron Nitride Atomic Sheets with an Engineered Bandgap and Magnetization

Controlled doping of flat atomic sheets of boron nitride (BN) can in principle break charge and spin symmetries. In contrast to graphene that oxidizes at >500 °C, due to its high melting point (ca. 2700 K) and the electrically insulating nature (Eg ∼ 5.5 eV), BN presents strong material candidature for flexible magnetic memory chips that are functional even under fire. Here, we report the transition metal (Fe and Cr) doping of BN by microwave and solvothermal methods. X-ray photoelectron spectroscopy reveals ∼17% doping by microwave (800 W) and <11% doping by the solvothermal method. Cr or Fe doping brings the bandgap down to ∼3.6 or ∼2.0 eV, respectively, for the doped BN samples. Cr doping by microwave results in intrinsic ferromagnetic ordering evident from the high Curie point (∼380 K) in contrast to orbital-mediated magnetic ordering in solvothermal Cr-doped BN systems. Fe doping raises magnetization values in particular. Spin-polarized DFT band structure calculations suggest vivid spin asymmetry caused by doping, supporting our experimental findings on doped BN samples.

Panax notoginseng powder -assisted preparation of carbon-quantum-dots/BiOCl with enriched oxygen vacancies and boosted photocatalytic performance

Low activity of photocatalysts is a serious bottleneck to the practical application of photocatalytic technology. In this paper, a series of BiOCl composite photocatalysts containing carbon quantum dots (CQDs) were successfully prepared by adding Panax notoginseng powder (PNP) to the solvothermal synthesis system of BiOCl as a template agent and a raw material for 0D CQDs. CQDs/BiOCl exhibit 2D flake structures and 3D flower-like microspheres self-assembled from thin flakes, holding rich oxygen vacancies (OVs). After detailed characterization, it was found that the amount of OVs on BiOCl could be regulated according to the amount of PNP added. The CQDs/OVs-BiOCl photocatalysts exhibit higher photogenerated charge separation efficiency and photocatalytic activity than the bare BiOCl. When the mass ratio of PNP/BiOCl is 1.0%, the photocatalyst demonstrates the maximum degradation activity for rhodamine B (RhB) and perfluorooctanoic acid (PFOA). In view of the solid observations, a photocatalytic enhancement mechanism of CQDs/BiOCl was elucidated.

Comparative life cycle assessment on zeolitic imidazolate framework-8 (ZIF-8) production for CO2 capture

Metal-organic frameworks (MOFs) combine the advantages of both organic and inorganic materials. Among the synthesized MOFs, ZIF-8 is promising for CO2 capture, raising the need for its sustainable production. The life cycle assessment (LCA) of various ZIF-8 synthesis methods such as solvothermal (DMF), solvothermal (MeOH), microwave, sonochemical, mechanochemical, dry-gel conversion and aqueous system was investigated. The findings indicated that the seven production methods have the highest impact on marine ecotoxicity, followed by human toxicity non-carcinogenic, and terrestrial ecotoxicity among the 18 categories of evaluation studies. The main contributor towards environmental degradation was the solvent for washing, N, N-dimethylformamide (DMF) in most of the methods. It is also revealed that replacing the solvent of DMF with methanol remarkably reduced the influence on human health, ecosystem and resources in the solvothermal (MeOH) method as compared to the solvothermal (DMF) method. As a whole, the mechanochemical method has the least impact on the environment because it has fewer production steps and is easy to operate. Therefore, this work delineates comprehensive environmental influences of different ZIF-8 synthesis methods to lay the groundwork for its mass and sustainable production.

Effectively destruction of rhodamine B and perfluorooctanoic acid over BiOCl with boosted separation ability of carriers benefited from tunable oxygen vacancies

BiOCl-based photocatalysts have triggered considerable concern because of the unique layered crystal structures and electronic band structures. Construction of oxygen vacancies (OVs) can promote photocatalytic activity, which provides a new insight into understanding the separation and migration behavior of photoexcited carriers. In this study, BiOCl photocatalysts were manufactured through a solvothermal method via adding polyvinyl alcohol 1700 (PVA 1700) into the solvothermal synthetic system. The PVA-BiOCl samples (BiOCl prepared with the assistance of PVA 1700) have visible light-responsive capacity and display stronger separation ability of photoinduced charge than the reference BiOCl, proven by surface photovoltage spectroscopy (SPS) and electrochemical tests. The PVA-BiOCl samples hold richer OVs compared with the blank BiOCl. The destruction ability of PVA-BiOCl was studied by elimination of rhodamine B (RhB) and perfluorooctanoic acid (PFOA) under visible light and mercury lamp irradiation, respectively. The consequences show that the PVA-BiOCl has better photocatalytic properties than the blank BiOCl. When the weight ratio of PVA 1700/BiOCl is 4.4, the sample possesses the supreme photocatalytic property, the photocatalytic performance of the sample is two-fold of that of the blank BiOCl and the sample exhibits high structural stability. Combined with all the results, photocatalytic mechanism of PVA-BiOCl was discussed and revealed.

Enhanced visible-light photocatalytic performance of ZIF-8-derived ZnO/TiO2 nano-burst-tube by solvothermal system adjustment

A novel strategy for the preparation of heterojunction derivants by regulating the loading of precursors was proposed and applied for the first time to effectively remove dyes and antibiotics. Zeolite imidazole framework-8 (ZIF-8)-derived ZnO/TiO2 nano-burst-tube (NBT) was prepared by calcination of ZIF-8 as precursor grown in a solvothermal system adjusted by NH4OH or NaOH, TiO2 NBT as solvothermal substrate. Through a reasonable selection of solvothermal system, ZIF-8-derived ZnO/TiO2 NBT not only provides enhanced specific surface area (1012.3 m2/g), but also enhances the visible light response and charge separation of TiO2 NBT, whose instantaneous photocurrent density is up to 53 mA cm−2, which is three times that of TiO2 NBT. Under visible light irradiation, ZnO/TiO2 NBT achieved rapid degradation of Rhodamine B(RhB), tetracycline hydrochloride (TCH) and chlortetracycline hydrochloride (CTC) with complete removal within 20 min, outperforming ZnO, ZIF-8, TiO2 NBT and ZIF-8/TiO2 NBT, with excellent cyclic photocatalytic performance. The results show that the degradation pathways of RhB, TCH and CTC are different. The work provides a promising strategy for multifunctional derivative photocatalytic materials preparation.

Tunable oxygen vacancies facilitated removal of PFOA and RhB over BiOCl prepared with alcohol ether sulphate

In this study, surfactant sodium alcohol ether sulphate (AES) was added into the solvothermal preparation system of BiOCl to decrease the surface energies of the (010) facets during the crystallization process. BiOCl samples were synthesized by controlling the amount of AES. BiOCl samples prepared with the assistance of AES have a smaller size, higher oxygen vacancies (OVs) and photogenerated electron and hole pairs (e-/h+) separation efficiency than the reference BiOCl (R-B). The content of OVs can be facilely controlled by using the different amount of AES. When the weight ratio of AES/BiOCl is 5%, the BiOCl prepared (5% AB) has suitable OVs content to hoist the separation of photoinduced charge, displaying the highest photocatalytic activity. Photocatalytic degradation ability of the 5% AB sample toward destruction of Rhodamine B (RhB) under visible light is 4.4 times of that of R-B, and the degradation rate constant and defluorination rate of perfluorooctanoic acid (PFOA) over 5% AB under UV light for 2 h is 2.9 times and 1.5 times of that over R-B, respectively. Given the experimental observations, enhancement mechanism in photocatalytic property was proposed.

Stabilizing emulsions using high-amylose maize starch treated by solvothermal process

This paper proposes a method to modify high-amylose maize starch (HAMS) with lauric acid in an ethanol solvothermal system to prepare a cold-water swelling esterified starch (M-HAMS). Using M-HAMS as a granule stabilizer, oil-in-water Pickering emulsions were prepared, and factors affecting the oxidation stability of emulsion, such as granule content, oil-water ratio, pH value, and NaCl concentration, were studied. Atomic force microscopy (AFM) analysis showed that M-HAMS granules swell into dense molecular chains liking a three-dimensional network barrier in the emulsion, which increases the viscosity of continuous phase and prevents the oil droplets from contacting the pro-oxidant in the water phase, thus reducing the peroxide value. At the same time, the influence of changes in pH value and NaCl concentration on the viscosity and stability of emulsion is weakened. Therefore, the preparation of M-HAMS granule by ethanol solvothermal is a simple and effective method.

Enhanced gas sensing performances of hydrogenated MnO octahedrons with {111} facets and the sensing mechanism of unsaturated Mn as a reactive atom

MnO octahedrons with exposed {111} crystal faces have been synthesized in a solvothermal system of Mn(Ac)2 and C2H5OH at 200 °C for 48 h. Formation of the MnO octahedron results from the selective adsorption of -OCH2CH3 and -OH groups on the (111) crystal plane. Responses of the MnO octahedrons towards acetone, triethylamine, ethanol and n-Butylamine are enhanced by increasing numbers of the unsaturated 2, 3 and 5-coordinated Mn atoms on the (111) surface by removing surface C2H5O- and -OH groups through hydrogenation. Thus, the exposed Mn-MnO (111) face is found to be a gas sensing active surface, the unsaturated 2, 3 and 5-coordinated Mn atoms on the (111) surface are evidenced to be the sensing reactive atoms and a detailed sensing mechanism is presented. The unsaturated active Mn atoms produce electrons, adsorb oxygen and catalyze the sensing reactions. The mechanism can deepen the understanding of the nature of oxide semiconductor gas sensing and is helpful to the design of high performance gas sensing materials.

Efficient synthesis of N-doped porous carbon nanoribbon composites with selective microwave absorption performance in common wavebands

One-dimensional carbon-based nanomaterials possess unique advantages in the field of microwave absorption due to their special structure. Structure design and synthesis method development of new one-dimensional carbon-based microwave absorbers are of great significance. In this paper, a rapid preparation method for N-doped porous carbon nanoribbon composites is reported, and a series of high-efficiency lightweight microwave absorbers have been obtained. They can meet the requirements of different microwave absorption scenarios. Firstly, an organic-inorganic hybrid nanomaterial with ribbon-shaped structure (HNR) is synthesized by solvothermal system. Then, N-doped porous carbon nanoribbon composites with different components are obtained by using HNR as precursor and being calcined at different temperature. The microwave absorbing properties show frequency selectivity. ZnS/ZnO@N-doped porous carbon nanoribbons (ZnS/ZnO@NPCNRs) exhibit best absorption performance in Ku band and achieve full band absorption with a minimum reflection loss of −56.1 dB. ZnS@N-doped porous carbon nanoribbons (ZnS@NPCNRs) have the strongest absorption in X band. The minimum reflection loss is −55.3 dB. N-doped porous carbon nanoribbons (NPCNRs) show obvious advantages in C band and S band under an ultra-low filler content of 4%. This work proposes a rapid synthesis method for ribbon-shaped carbon-based nanomaterials and provides new candidates for different microwave absorption scenarios.

Investigation on [OH−]-responsive systems for construction of one-dimensional hydroxyapatite via a solvothermal method

The concentration of OH− can directly influence the crystal growth of flexible hydroxyapatite nanofibers in oleic acid-assisted solvothermal reaction systems.

BiOBr/Ti3C2 nanocomposites prepared via an octanol solvothermal method to achieve enhanced visible photocatalytic properties

BiOBr nanospheres grown in situ on lamellar Ti3C2 were synthesised in an octanol solvothermal system to obtain BiOBr/Ti3C2 heterojunction composites with high visible photocatalytic activity (OBT).