Low-temperature Solvothermal Method Research Articles

Cost effective synthesis of 3-dimensional V4O9: A promising high-capacity lithium cathode

The earthly abundant vanadium exhibits multi-oxidation states and different crystalline structures in their oxide compounds offering unique electrical, opto-electronic, and catalytic properties to be applicable for various applications including energy storage materials. The stable vanadium oxides (V2O5, VO2, V2O3) are mostly studied while metastable oxides such as V4O9 is less explored. The latter possesses a tridimensional (3D)-tunnel defect type structure with different polyhedral wherein VO5 pyramids and VO6 octahedra are connected by corner oxygen atoms from the VO4 tetrahedra with V4+ and V5+ oxidation states, respectively, making it an appealing host candidate for lithium-ions insertion. Herein, we present a cost-effective single pot synthesis of 3D V4O9 nanoparticles using versatile low temperature solvothermal method. The obtained material has been fully characterised in terms of phase identity and crystal structure using x-ray diffraction, Raman spectroscopy and high-resolution-transmission-electron-microscopy while surface composition and valence- and/ oxidation states using x-ray photoelectron spectroscopy followed by investigation of its electrochemical performance against lithium. Upon first discharge, V4O9 could intercalate ∼6 Li+ per formula unit corresponding to highest discharge capacity of 464.5 mA h g−1 and a reversible first Coulombic efficiency of 75.3% between 1.5 – 4.0 V against Li in a half-cell configuration. In the long run, the V4O9 exhibited a reversible capacity of 160.8 mA h g−1 at 100 mA g−1 even after 2000 cycles against lithium rendering it as suitable positive electrode with high capacity and cyclability for lithium-ion battery applications.

Porous Zn1-xCdxSe/ZnO Nanorod Photoanode Fabricated from ZnO Building Blocks Grown on Zn Foil for Photoelectrochemical Solar Hydrogen Production.

Solar energy is the most promising, efficient, environmentally friendly energy source with the potential to meet global demand due to its non-polluting nature. Herein, a porous Zn1-xCdxSe/ZnO nanorod (NR) heterojunction was synthesized by hydrothermal and low-temperature solvothermal methods. First, the ZnO NR was grown on a Zinc foil, and an inorganic-organic hybrid ZnSe(en)0.5 material was developed by the low-temperature solvothermal method. In this work, the ZnO NR acted as a base material and a building block for the growth of ZnSe(en)0.5. Moreover, after the solvothermal process, the reduced Se2- reacts with the ZnO NR and forms inorganic-organic hybrid ZnSe(en)0.5. After the selenization process, the obtained material shows a red brick color due to the absorbance of excessive Se metal particles during the solvothermal process. Furthermore, in order to enhance the photoelectrochemical properties, the Cd2+ ion exchange method was applied at various temperatures (140, 160, and 180 °C for 3 h) to produce a precursor material to a porous Zn1-xCdxSe/ZnO NR nanostructure. The optimum Zn1-xCdxSe/ZnO NR-160 photoanode showed a high photocurrent density of 7.8 mA·cm-2 at -0.5 V vs. Ag/AgCl with a hydrogen evolution rate of 199 μmol·cm-2/3 h. The improved photocurrent performance was attributed to effective light absorption and prolonged recombination lifetime.

Low-Temperature Solvothermal Method for Coal Tar-Based Carbonaceous Mesophase Preparation and Its Excellent Performance

Low-Temperature Solvothermal Method for Coal Tar-Based Carbonaceous Mesophase Preparation and Its Excellent Performance

La-doped LiMnPO4/C cathode material for Lithium-ion battery

LiMnPO4 and LiMn1-xLaxPO4 (0.01 ≤ x ≤ 0.1) nanostructures with in-situ carbon coating are synthesized by low temperature solvothermal method using Glycerol: Water (2:1) ratio as solvent. Powder X-ray diffraction (XRD) studies confirmed the orthorhombic crystal structure of LiMnPO4 and LiMn0.99La0.01PO4. X-ray diffraction shows that up to 1% La3+ ion doping into manganese sites does not affect the crystal structure of LiMnPO4. Field emission scanning electron microscopy (FESEM) of LiMnPO4 and LiMn0.99La0.01PO4 depicts the formation of nanosized particles with spherical morphology. Electrochemical properties of LiMnPO4 and LiMn0.99La0.01PO4 are investigated by galvanostatic charge discharge tests. The present studies show that 1% La3+ ion doped LiMnPO4 could be a promising cathode material that can improve the performance of Lithium-ion cell by increasing the electrochemical stability at higher C-rate.

Surfactant Assisted Synthesis of BiVO4 by Low Temperature Solvothermal Method: Effect of Calcination for Photocatalytic Activity

A visible light active semiconductor photocatalyst, BiVO4 was synthesized through low temperature solvothermal method in hot air oven followed by calcination. To enhance the degradation rate surfactants were employed, which shows the better degradation for calcinated hexamine added BiVO4, i.e. 74% of methylene blue was degraded in 180 min in visible light irradiation. The result is correlated with lower band gap energy value, i.e. 2.07 eV and lower photoluminescence emission spectra intensity. It was observed the variation in surface morphology of the prepared samples. The specific surface area of calcinated hexamine added BiVO4 was analyzed by BET analysis. All the prepared samples showed higher absorption in UV-visible region. The FTIR confirmed the presence of hexamine in the calcinated hexamine sample.

Construction of Highly Active Zn3In2S6 (110)/g-C3N4 System by Low Temperature Solvothermal for Efficient Degradation of Tetracycline under Visible Light.

Herein, Zn3In2S6 photocatalyst with (110) exposed facet was prepared by low temperature solvothermal method. On this basis, a highly efficient binary Zn3In2S6/g-C3N4 was obtained by low temperature solvothermal method and applied to the degradation of tetracycline (TC). The samples of the preparation were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, UV-vis diffuse reflection spectroscopy, and photoluminescence spectroscopy. Furthermore, the degradation performance of photocatalysts on TC was investigated under different experimental conditions. Finally, the mechanism of Zn3In2S6/g-C3N4 composite material degrading TC is discussed. The results show that Zn3In2S6 and Zn3In2S6/g-C3N4 photocatalysts with excellent performance could be successfully prepared at lower temperature. The Zn3In2S6/g-C3N4 heterojunction photocatalyst could significantly improve the photocatalytic activity compared with g-C3N4. After 150 min of illumination, the efficiency of 80%Zn3In2S6/g-C3N4 to degrade TC was 1.35 times that of g-C3N4. The improvement of photocatalytic activity was due to the formation of Zn3In2S6/g-C3N4 heterojunction, which promoted the transfer of photogenerated electron-holes. The cycle experiment test confirmed that Zn3In2S6/g-C3N4 composite material had excellent stability. The free radical capture experiment showed that ·O2- was the primary active material. This study provides a new strategy for the preparation of photocatalysts with excellent performance at low temperature.

Self-assembled Cr2O3@nanogel/Au nanozymes to simulate peroxidase activity as a H2O2 sensor

The low temperature solvothermal method synthesized Cr2O3 NPs has not only peroxidase activity, but also oxidase activity. Then, the oxidase activity of Cr2O3 NPs is effectively shielded by nanogel immobilization using three monomers acrylamide, NIPAAM (N-isopropylacrylamide) and MBA (N,N′-methylene bisacrylamide) in HEPES (4-(2-hydroxyerhyl)piperazine-1-erhanesulfonic acid) buffer. Ultimately, the enzymatic activity of Cr2O3@nanogel/Au is significantly enhanced after doping Au NPs by SERS (Surface Enhanced Raman Spectroscopy) evaluation. A SERS strategy was proposed for the detection of H2O2 by Cr2O3@nanogel/Au. The linear range was 10−8 mol·L−1-10−1 mol·L−1.

Waste PET Plastic-Derived CoNi-Based Metal-Organic Framework as an Anode for Lithium-Ion Batteries.

Recycling waste PET plastics into metal–organic frameworks is conducive to both pollution alleviation and sustainable economic development. Herein, we have utilized waste PET plastic to synthesize CoNi-MOF applied to lithium battery anode materials via a low-temperature solvothermal method for the first time. The preparation process is effortless, and the sources’ conversion rate can reach almost 100%. In addition, the anode performance of MOFs with various Co/Ni mole ratios was investigated. The as-synthesized Co0.8Ni-MOF exhibits excellent crystallinity, purity, and electrochemical performance. The initial discharge and charge capacities are 2496 and 1729 mAh g–1, respectively. Even after 200 cycles, the Co0.8Ni-MOF electrode can exhibit a high Coulombic efficiency of over 99%. Consequently, given the environmental and economic benefits, the Co0.8Ni-MOF derived from waste PET plastic is thought to be an appealing anode material for lithium-ion batteries.

Synthesis of novel graphene aerogel encapsulated bismuth oxyiodide composite towards effective removal of methyl orange azo-dye under visible light.

Development of novel and eco-friendly composite photocatalysts for the efficient removal of contaminants from wastewater is the need of the hour. In this study, visible light responsive novel graphene aerogel/bismuth oxyiodide (GA/BiOI) composite was synthesized via low-temperature solvothermal method. The synthesized GA/BiOI composite was tested for methyl orange (MO) azo-dye degradation under visible light. The graphene aerogel nanosheets were wrapped onto the surface of the each individual BiOI microsphere, which encourages the interconnection charge transfer process. The light absorption properties of GA/BiOI composite were increased with the addition of graphene aerogel. The optimal 5%-GA/BiOI composite displayed higher MO removal efficiency, which is ∼2 fold more than the bare BiOI photocatalyst. This enhanced photocatalytic activity was on account of lower recombination rate of charge carriers, improved light absorption, and the high surface area. In addition, the 5%-GA/BiOI composite showed good stability until 3 cycles without deactivation. The plausible MO degradation mechanism was also proposed over GA/BiOI under visible light. This work provides a new perspective on the design and synthesis of graphene aerogel-based composite for environmental applications.

In-situ constructed 2D/2D ZnIn2S4/Bi4Ti3O12 S-scheme heterojunction for degradation of tetracycline: Performance and mechanism insights

Semiconductor materials dominated photocatalytic technology is one of the most efficient approaches to degrade organic pollutants. However, the limited light absorption range and rapid recombination of photogenerated carriers greatly restrict the application of photocatalysts. Rational design of photocatalysts to achieve high catalytic activity and stability is of great importance. Herein, ZnIn2S4/Bi4Ti3O12 S-scheme heterojunction is synthesized by growing the ZnIn2S4 nanosheets on the sheet-like Bi4Ti3O12 surface via a low-temperature solvothermal method. The TC removal efficiency of optimized heterojunction reaches 82.1% within 60 min under visible light, and the rate constant is nearly 6.8 times than that of pristine ZnIn2S4. The favorable photocatalytic performance of heterojunction is attributed to the tight contact interface and efficient separation of photogenerated carriers. Besides, the difference in work function between ZnIn2S4 and Bi4Ti3O12 leads to band bending and the establishment of built-in electric field on the contact interface of heterojunction, which facilitates the migration and separation of photogenerated carriers. Furthermore, the cycling test demonstrates the attractive stability of heterojunction. The possible TC photodegradation pathways and toxicity assessment of the intermediates are also analyzed. In conclusion, this work provides an effective strategy to prepare S-scheme heterojunction photocatalysts with favorable photocatalytic activity, which can enhance wastewater purification efficiency.

Ternary heterostructures of 1D/2D/2D CuCo2S4/CuS/Ti3C2 MXene: Boosted amperometric sensing for chlorpyrifos

Multicomponent heterogeneous Ti3C2 transition metal carbide (MXene)-based materials are receiving extensive research attention due to their interesting synergistic interactions and catalytic properties. However, the morphology-controllable synthesis of heterostructures as structural stabilizers for Ti3C2 MXene remains a challenge owing the complicated synthesis procedure. In this work, a kind of ternary heterogeneous nanomaterials CuCo2S4/CuS/Ti3C2 MXene with a nanorod/nanoplate/nanosheet hybrid architecture is constructed through a one-step low-temperature solvothermal method. The well-designed ternary one-dimensional (1D)/two-dimensional (2D)/2D CuCo2S4/CuS/Ti3C2 MXene heteromaterials exhibit synergistic improvements in substrate-catalyzed reactions for electrochemical acetylcholinesterase (AChE) biosensor. The Michaelis-Menten constant for the Nafion/AChE/CuCo2S4/CuS/Ti3C2 MXene/GCE biosensor is 228 μM, which is smaller than ones reported in previous literatures, indicating a higher affinity of the fabricated enzyme biosensor to acetylthiocholine chloride. The biosensor exhibits a well linear relationship with chlorpyrifos concentration ranging from 2.852 × 10−12 M to 2.852 × 10−6 M. The multicomponent 1D/2D/2D CuCo2S4/CuS/Ti3C2 MXene heteromaterial may shine a light in more electrochemical applications.

Synthesis and photoresponse study of vertically oriented CuO/ZnO nanorod arrays based on solution methods

Low temperature solvothermal method is employed to fabricate hierarchical CuO coated ZnO Nanorod Arrays (NRs) on p-Si. The device is characterized and the photoluminescence result indicates that ZnO NRs coupling with CuO nanostructure has high optical quality. Meanwhile, the experiment shows that obtained detector displays excellent infrared (IR) light sensing properties with fast response without external bias. The device has excellent stability and repeatability under 940 nm at zero bias voltage. The dark current of CuO@ZnO NRs device is 7.1 × 10−10 A, and Ilight/Idark ratio is 155. Furthermore, the response results indicated that the coupling of CuO with and ZnO NRs to construct heterojunction nanostructure has fast response speed and responsibility (<1.5 ms). The unique hierarchical CuO@ZnO NRs will offer high surface-to-volume ratio and efficient electron transport which can accelerate carrier separation and facilitate electron-hole transfer. It will provide an effective method to assemble high performance photodetectors based on metal oxide with low cost.

Hierarchical NiCo2S4/ZnIn2S4 heterostructured prisms: High-efficient photocatalysts for hydrogen production under visible-light

Exploring low-cost co-catalyst to ameliorate the photocatalytic activity of semiconductors sets a clear direction for solving energy crisis and achieving efficient solar-chemical energy conversion. In this work, a unique hierarchical hollow heterojunction was constructed by in-situ growing ZnIn2S4 nanosheets on the porous NiCo2S4 hollow prisms through a low temperature solvothermal method, in which NiCo2S4 with semi-metal property acted as non-noble metal co-catalyst. NiCo2S4 co-catalyst was innovatively encapsulated in ZnIn2S4, which not only relieved the light shielding effect caused by the large loading amount of co-catalyst, but also supplied abundant active sites for H2 evolution. The hierarchical hollow heterostructure of NiCo2S4/ZnIn2S4 provided a highly efficient channel for charge transfer. Combining these advantages, NiCo2S4/ZnIn2S4 composite demonstrated excellent photocatalytic activity. In the absence of sacrificial agent, the NiCo2S4/ZnIn2S4 photocatalyst achieved a remarkable improved H2 yield of 0.77 mmol g−1h−1 under visible light irradiation (λ > 400 nm), which is 6.6 times greater than that of ZnIn2S4. Besides, NiCo2S4 even exhibited better performance on the H2 evolution improvement of ZnIn2S4 than precious metal Pt. This work will offer novel insights into the reasonable design of non-noble metal photocatalysts with respectable activity for water splitting.

Effect of the organic sulfur source on the photocatalytic activity of CdS.

By controlling the species of the organic sulfur source, CdS samples were produced with different photocatalytic performances by a low-temperature solvothermal method. Different species of the organic sulfur source were chosen as the coordination agent to control the interactions in the crystal growth process. Among them, thioacetamide was the best coordination agent. The hydrophobic chain could be good for reducing the resistance of charge transfer, and increasing the rate of surface charge transfer and the lifetime of the photoexcited electrons. Benefiting from the hydrophobic chain, CdS shows an excellent photocatalytic hydrogen evolution rate of 943.54 μmol h−1 g−1 and a rhodamine B photocatalytic degradation rate of 99.1% in 60 min, which is superior to the photocatalysis of pure CdS prepared by many other methods.

Solvent-assisted preparation of low-temperature SnO2 electron transport layers for efficient and stable perovskite solar cells made in ambient conditions

High-quality SnO2 electron transport layers were synthesized by a simple low-temperature solvothermal method.

Solvothermal Synthesis of [Cr7 S8 (en)8 Cl2 ]Cl3  ⋅ 2H2 O with Magnetically Frustrated [Cr7 S8 ]5+ Double-Cubes.

A novel transition metal chalcohalide [Cr7S8(en)8Cl2]Cl3 ⋅ 2H2O, with [Cr7S8]5+ dicubane cationic clusters, has been synthesized by a low temperature solvothermal method, using dimethyl sulfoxide (DMSO) and ethylenediamine (en) solvents. Ethylenediamine ligand exhibits bi‐ and monodentate coordination modes; in the latter case ethylenediamine coordinates to Cr atoms of adjacent clusters, giving rise to a 2D polymeric structure. Although magnetic susceptibility shows no magnetic ordering down to 1.8 K, a highly negative Weiss constant, θ=−224(2) K, obtained from Curie‐Weiss fit of inverse susceptibility, suggests strong antiferromagnetic (AFM) interactions between S=3/2 Cr(III) centers. Due to the complexity of the system with (2S+1)7=16384 microstates from seven Cr3+ centers, a simplified model with only two exchange constants was used for simulations. Density‐functional theory (DFT) calculations yielded the two exchange constants to be J 1=−21.4 cm−1 and J 2=−30.2 cm−1, confirming competing AFM coupling between the shared Cr3+ center and the peripheral Cr3+ ions of the dicubane cluster. The best simulation of the experimental data was obtained with J 1=−20.0 cm−1 and J 2=−21.0 cm−1, in agreement with the slightly stronger AFM exchange within the triangles of the peripheral Cr3+ ions as compared to the AFM exchange between the central and peripheral Cr3+ ions. This compound is proposed as a synthon towards magnetically frustrated systems assembled by linking dicubane transition metal‐chalcogenide clusters into polymeric networks.

Hetero-structured ZnIn2S4-NiO@MOF photo-catalysts for efficient hydrogen evolution

To obtain a high-performance heterogeneous photo-catalyst, herein, the hetero-structured ZnIn2S4-NiO@MOF (ZNM) nano-sheets are designed and prepared by partial pyrolysis of nickel-based MOFs (Ni-MOF) combined with the low-temperature solvo-thermal method. The results indicate that the NiO nanoparticles, produced by partial pyrolysis of the Ni-MOF, have a high density of the surface active sites with limited aggregation, which act as a co-catalyst to capture photo-induced charge carriers. In addition, the morphology and structure of Ni-MOF nano-sheets were preserved in ZNM, which is beneficial to the reduction of the conduction barrier for the photo generated electron-hole pairs. With the synergetic advantages of co-catalyst and unique two-dimensional hetero-structure, ZNM nano-sheets exhibited significantly improved activity for photo-catalytic hydrogen production.

Formation of unique hollow ZnSnO3@ZnIn2S4 core-shell heterojunction to boost visible-light-driven photocatalytic water splitting for hydrogen production

Herein, it is reported that a batch of hollow core-shell heterostructure photocatalysts were carefully fabricated using a reliable and convenient low-temperature solvothermal method, and ultra-thin ZnIn2S4 nanosheets are grown in situ on the hollow ZnSnO3 cubes to achieve efficient photocatalytic hydrogen evolution. This unique layered hollow structure utilizes multiple light scattering/reflection within the cavity to enhance light absorption, the thin shell reduces the path of charge transfer, and the irregular nanosheets-wrapped outer layer not only enhances the adsorption power, but also provides an abundant active sites to promote the efficiency of photocatalytic water splitting to produce hydrogen. Therefore, due to the matching energy band and unique structure, the ZnSnO3@ZnIn2S4 hollow core-shell heterostructure photocatalyst exhibits superior H2 production efficiency (16340.18 μmol h−1 g−1) and outstanding stability. This work emphasizes the importance of carefully designing a suitable material structure in addition to adjusting the chemical composition.

Porous hollow ZnCo2S4 nanosheet arrays derived from metal-organic framework as efficient cathode for lithium oxygen batteries

Rechargeable non-aqueous lithium oxygen batteries (LOBs) have attracted extensive attention as the most promising next-generation battery technologies due to their extremely high theoretical energy density. However, their practical applications are hampered by sluggish reaction kinetics and severe parasitic reactions, resulting from the insulating and insoluble discharge product-Li2O2. Herein, self-standing ZnCo2S4 nanosheet arrays derived from metal-organic framework (MOF) via low-temperature solvothermal sulfuration method, are fabricated as efficient cathode for LOBs. The hollow structure of ZnCo2S4 nanosheet formed during sulfuration provides more catalytic sites and alleviates stress during repeated discharge/charge progress, while three-dimensional (3D) porous architecture inheriting from MOF shortens the transportation pathway of Li+ and O2 in electrolyte. Compared with pure CoS derived from Co-MOF, more Co3+ exposes on ZnCo2S4 surface due to the introduction of Zn, enhancing the catalytic activity distinctly. Benefitting from the bifunctional catalytic performance, the ZnCo2S4 cathode exhibits an extremely high initial discharge capacity of 9505 mAh g−1 at 100 mA g−1. Additionally, it also achieves a smaller overpotential of 1.02 V under a cutoff capacity of 1000 mAh g−1 and a longer cycle life of 90 cycles at 100 mA g−1. This work provides new insights into designing efficient bifunctional catalyst for LOBs.

Tuning Fe-Se Tetrahedral Frameworks by a Combination of [Fe(en)3]2+ Cations and Cl- Anions.

A one-dimensional (1D) chain compound (en = ethylenediamine), featuring tetrahedral FeSe2 chains separated by [Fe(en)3]2+ cations and Cl- anions, has been synthesized by a low temperature solvothermal method using simple starting materials. The degree of distortion in the Fe-Se backbone is similar to previously reported compounds with isolated 1D FeSe2 chains. 57Fe Mössbauer spectroscopy reveals the mixed-valent nature of [Fe(en)3]3(FeSe2)4Cl2 with Fe3+ centers in the [FeSe2]- chains and Fe2+ centers in the [Fe(en)3]2+ complexes. SQUID magnetometry indicates that is paramagnetic with a reduced average effective magnetic moment, μeff = 9.51 μB per formula unit, and a negative Weiss constant, θ = -10.9(4) K, indicating antiferromagnetic (AFM) nearest neighbor interactions within the [FeSe2]- chains. Weak antiferromagnetic coupling between chains, combined with rather strong intrachain AFM coupling, leads to spin-glass behavior at low temperatures, as indicated by a frequency shift of the peak observed at 3 K in AC magnetic measurements. A combination of [Fe(en)3]2+ and Cl- ions is also capable of stabilizing mixed-valent 2D Fe-Se puckered layers in the crystal structure of [Fe(en)3]4(Fe14Se21)Cl2, where Fe14Se21 layers have a unique topology with large open pores. Property measurements of [Fe(en)3]4(Fe14Se21)Cl2 could not be performed due to the inability to either grow large crystals or synthesize this material in single-phase form.