Facile One-pot Solvothermal Route Research Articles

Defect engineered 2D mesoporous Mo-Co-O nanosheets with crystalline-amorphous composite structure for efficient oxygen evolution

Two-dimensional (2D) mesoporous metal-oxide (hydroxide) nanomaterials with defects are promising towards the realization of efficient electrocatalysis. Herein, we report a facile and effective one-pot solvothermal route to synthesize mesoporous Mox-Co-O hybrid nanosheets (NSs) which is composed of crystalline Mo4O11 and amorphous cobalt hydroxide. Due to the corrosion of 1-octylamine at high temperatures, abundant mesoporous holes are created in situ over the Mox-Co-O hybrid NSs during the solvothermal process, which is beneficial to increasing the electrochemical surface area. The dimension of the Mox-Co-O NSs, size of mesoporous and the concentration of defects can be easily modulated by controlling the molar ratio of Mo/Co. Electrochemical measurements reveal that the 2D mesoporous Mox-Co-O NSs show an excellent activity for the oxygen evolution reaction with the highest catalytic activity of η10 = 276 mV at 10 mA cm−2 in 1 mol L−1 KOH. Enhanced adsorption of intermediates and abundant oxygen vacancies achieved by appropriate Mo doping are the two main factors that contribute to the excellent catalytic activity of Mo0.2-Co-O NSs. This work, with the construction of 2D metal-oxide (hydroxide) crystalline-amorphous nanomaterials possessing abundant holes, oxygen vacancies and enhanced adsorption of intermediates, provides important insight on the design of more efficient catalysts.

Ultrathin molybdenum disulfide nanosheet-coated acetylene black: One-pot synthesis and electrocatalytic hydrogen evolution

Molybdenum disulfide (MoS2) and its composites are the promising electrocatalysts for the hydrogen evolution reaction (HER) in acidic solution because it is earth-abundant and low-cost. Here we reported the ultrathin molybdenum disulfide nanosheet-coated acetylene black (AB) coated (MoS2@AB) as the electrocatalysts for the HER. The catalysts were synthesized in a facile one-pot solvothermal route. The as-prepared catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM, X-Ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The results show that the MoS2 nanosheets on AB have a few layers and many surface defects, which are benefical to the HER catalysis. Electrochemical tests revealed that the existence of AB can't only make the catalyst expose a considerable amount of active sites but also increase the turnover frequency (TOF) value per site. In addition, the MoS2@AB(75) had excellent electro-catalytic HER performances with a low onset potential (−110 mV), a small Tafel slope (50–60 mV per decade) and the longtime stability (10 h).

Facile synthesis of Bi-modified Nb-doped oxygen defective BiOCl microflowers with enhanced visible-light-driven photocatalytic performance

Bi-modified Nb-doped oxygen defective BiOCl hierarchical microflowers were synthesized through a facile one-pot solvothermal route. The prepared photocatalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results indicated that the modified BiOCl appeared as hierarchical microflowers composed of nano sheets. The BiOCl synthesized with Nb/Bi = 1:7 in precursor solutions exhibited the best photocatalytic performance for Rhodamine B (RhB) and Tetracycline (TC) degradation under visible light irradiation. Compared with the BiOCl fabricated through a hydrothermal method, the counterpart with oxygen vacancies (OVs) had a better visible-light-driven photocatalytic activity, and the kinetics constant k for the degradation of RhB increased by 728% (525% for TC). After the modification of Bi0 and Nb5+, the constant k further increased by 134% and 82%, respectively, for the degradation of RhB and TC. This enhanced photocatalytic activity was attributed to both the improved visible light absorption caused by the introduction of OVs and the highly efficient separation of photoexcited carriers resulted from Nb5+ doping and Bi0 deposition. Trapping experiments revealed that the photogenerated hole was the dominating active species. This work provides a new facile strategy for the synthesis of visible-light-driven photocatalysts with high performance.

In2S3/CuS nanosheet composite: An excellent visible light photocatalyst for H2 production from H2S

As hydrogen sulfide (H2S) is a toxic chemical emitted in large quantities from both natural sources and industrial processes, resource utilization of H2S has become a hotspot research in recent years. We report herein, synthesis and characterization of a highly active In2S3/CuS nanosheet composite photocatalyst via a facile one-pot solvothermal route. The as-obtained In2S3/CuS composite show a special hierarchical structure and remarkable visible light absorption ability with an absorption edge of 785 nm. Its remarkable light absorption ability enables it to fully absorb the visible light. The as-obtained In2S3/CuS composite exhibits a superior visible-light photocatalytic activity and long-term durability in H2S splitting. As a result, a maximum H2 production rate of 14950 μmol g−1 h−1 over In2S3/CuS composite has been achieved even without any noble metal co-catalysts, which is 404 and 87 fold higher than that of over bare β-In2S3 and Cu9S5, respectively. The corresponding apparent quantum yield (AQY) of In2S3/CuS at 420 nm is 9.3%. The excellent photocatalytic activity depends on the chemical structure, phase, optical nature and folded nanosheet like geometry of In2S3/CuS composite, which facilitated electron transfer between interfaces of β-In2S3 and CuS, and improved the separation of photogenerated electron-hole pairs. Therefore, In2S3/CuS composite could serve as an efficient and practical visible-light response photocatalyst for H2 production from toxic and corrosive H2S.

Sodium Acetate Orientated Hollow/Mesoporous Magnetite Nanoparticles: Facile Synthesis, Characterization and Formation Mechanism

Monodispersed magnetite (Fe3O4) nanospheres with hollow or porous interior structures were synthesized by a facile one-pot solvothermal route. The facile synthetic process was carried out by using iron (III) chloride hexahydrate (FeCl3·6H2O) as only ferric ion resource, and anhydrous sodium acetate (NaAc) as structure-directing agent in an ethylene glycol solution without any templates or surfactants involved. The sizes, morphologies, crystal structures and magnetic properties of hollow Fe3O4 NPs are characterized via Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and Vibrating sample magnetometer (VSM) techniques. The influences of reaction time, molar ratio of reactants on the morphologies and magnetic performances are also investigated. The different morphologies of magnetite (Fe3O4) particles were presented with tunable size ranging from 85 to 250 nm and controllable structures including porous and hollow construction by using different amount of anhydrous NaAc. A plausible mechanism based on sodium acetate assistant local Ostwald ripening is proposed for acquiring the tailorable morphology and magnetic performance. Such a design conception of anhydrous NaAc assisted Ostwald ripening applied here is a significant alternative for synthesizing hollow magnetic particles, and it could elucidate some light to understand and construct other novel hollow/mesoporous nanostructures.

Boosting visible light photoreactivity of photoactive metal-organic framework: Designed plasmonic Z-scheme Ag/AgCl@MIL-53-Fe

In this work, we report the efficient integration of plasmonic Ag/AgCl with a typical photoactive metal-organic framework (MOF, MIL-53-Fe) to boost the visible light photoreactivity of MOFs. The Ag/AgCl@MIL-53-Fe photocatalysts are rationally designed and successfully prepared by a facile one-pot solvothermal route, where the Ag/AgCl nanoparticles are firmly anchored on the surface of MIL-53-Fe microrods. The formed structure is in favor of the synergetic transfer of photoinduced electrons and holes in the Ag/AgCl@MIL-53-Fe by a Z-scheme mechanism, ensuring the long lifetime of charge carriers and yielding the enhanced photocatalytic activity. The photocatalytic experiments reveal that Ag/AgCl@MIL-53-Fe is highly efficient for organic pollutant degradation and Cr(VI) reduction under visible light irradiation. The photocatalytic reactivity of Ag/AgCl@MIL-53-Fe is about 21.4 times and 10.8 times higher than that of bare MIL-53-Fe for the degradation of RhB and reduction of aqueous Cr(VI), respectively. Our finding on photoredox of Ag/AgCl@MIL-53-Fe would bring new insight into the design and development of highly efficient MOF-based photocatalysts.

Construction of 2D MoS2/PbS heterojunction nanocomposites with enhanced photoelectric property

Constructing heterojunction is one of the methods to restrain the hole-electron recombination and thus improve the photoelectric property. In this work, PbS nanoparticles were grown directly on ultra thin MoS2 nanosheets to fabricate 2D MoS2/PbS nanocomposites via a facile one-pot solvothermal route. PbS nanoparticles anchored on MoS2 sheets exhibited high crystallinity and uniformity. The particle size can be controlled by varying the precursor concentration. The nanocomposites displayed higher photocurrent compared with pristine MoS2, due to the improved light harvesting and the construction of p-n heterojunction structure.

Hydrothermal synthesis of the clustered network-like Ni3S2-Co9S8 with enhanced electrochemical behavior for supercapacitor electrode

In this work, a facile one-pot solvothermal route has been employed in preparing the clustered network-like Ni3S2-Co9S8 on Ni foam substrate (Ni3S2-Co9S8/NF) worked as electrode of supercapacitor. Ni3S2-Co9S8/Ni foam obtained showed a high specific capacitance of 5.37 F cm2 at a current density of 5 mA cm2. Furthermore, an asymmetric supercapacitor has been assembled using Ni3S2-Co9S8/NF as positive electrode and activated carbon (AC) as negative electrode. The resulting Ni3S2-Co9S8/NF//AC device exhibited a high energy density of 17 Wh kg−1 at a power density of 1.4 kW kg−1 with good cycling performance (80% of the initial capacitance retention after 1000 cycles). The superior electrochemical performance can be attributed to the combined contribution of both component and unique clustered network-like. The results demonstrate that the Ni3S2-Co9S8/NF is promising as electrode material for supercapacitors in energy storage.

Platinum-nickel alloy excavated nano-multipods with hexagonal close-packed structure and superior activity towards hydrogen evolution reaction

Crystal phase regulations may endow materials with enhanced or new functionalities. However, syntheses of noble metal-based allomorphic nanomaterials are extremely difficult, and only a few successful examples have been found. Herein, we report the discovery of hexagonal close-packed Pt–Ni alloy, despite the fact that Pt–Ni alloys are typically crystallized in face-centred cubic structures. The hexagonal close-packed Pt–Ni alloy nano-multipods are synthesized via a facile one-pot solvothermal route, where the branches of nano-multipods take the shape of excavated hexagonal prisms assembled by six nanosheets of 2.5 nm thickness. The hexagonal close-packed Pt–Ni excavated nano-multipods exhibit superior catalytic property towards the hydrogen evolution reaction in alkaline electrolyte. The overpotential is only 65 mV versus reversible hydrogen electrode at a current density of 10 mA cm−2, and the mass current density reaches 3.03 mA μgPt−1 at −70 mV versus reversible hydrogen electrode, which outperforms currently reported catalysts to the best of our knowledge.

Three-Dimensional Branched TiO2 Architectures in Controllable Bloom for Advanced Lithium-Ion Batteries.

Three-dimensional branched TiO2 architectures (3D BTA) with controllable morphologies were synthesized via a facile template-free one-pot solvothermal route. The volume ratio of deionized water (DI water) and diethylene glycol in solvothermal process is key to the formation of 3D BTA assembled by nanowire-coated TiO2 dendrites, which combines the advantages of 3D hierarchical structure and 1D nanoscale building blocks. Benefiting from such unique structural features, the BTA in full bloom achieved significantly increased specific surface areas and shortened Li(+) ion/electrons diffusion pathway. The lithium-ion batteries based on BTA in full bloom exhibited remarkably enhanced reversible specific capacity and rate performance, attributing to the high contact area with the electrolyte and the short solid state diffusion pathway for Li(+) ion/electrons promoting lithium insertion and extraction.

Highly porous TiO2 hollow microspheres constructed by radially oriented nanorods chains for high capacity, high rate and long cycle capability lithium battery

Hierarchical nanorods chains-constructed TiO2 hollow microspheres (HNC-TiO2-HMSs) have been designed and prepared through a facile one-pot fluorine-free solvothermal alcoholysis route using TiCl4 and isopropanol reaction system. Owing to the assembly of radially oriented nanorods chains leading to the formation of the shell of the hollow spheres, a large series of straight channels along nanorods chains are formed. Such highly porous hollow microspheres with hollow cavity, straight nanorods chains and straight nanochannels are highly desirable for Li ions batteries because such structure can easily store the electrolyte, facilitate the charge diffusion and Li+ insertion and buffer the volume change during the Li+ insertion/extraction process. One of the key innovation of the present work is the fine tuning of water amount released from the esterification of alcohol to induce in a well controlled hydrolysis of TiCl4 and engineer precisely HNC-TiO2-HMSs formation. Most importantly, the released Cl− ions direct the nanorods growing along (001) crystal plane and self-assembling along the radial direction accompanying with nanorods size controlling to form HNC-TiO2-HMSs. The obtained TiO2 anode material with such special structure demonstrates excellent Li+ storage capacity with outstanding cycle performance and superior rate capability at different rates over 700 cycles: a reversible capacity of 216mAhg−1 is obtained after 100 cycles at 1C and a reversible capacity of 112mAhg−1 is retained after 100 cycles at 10C. The SEM, TEM, HRTEM and in-situ XRD techniques have been utilized to shed light on the Li+ insertion process and the phase transformation. Most importantly, a self-improving phenomenon of cycle performance and storage capacity was observed owing to the formation of numerous ~5nm Li2Ti2O4 nanocrystals formed on the surface of the nanorods chains. The results reveal that the high performance of the as-prepared HNC-TiO2-HMSs in terms of storage capacity, cycle performance and rate capability can be attributed to the synergy of the special structure and the self-improving phenomenon. Our simple reaction system may provide a concrete example on the construction of novel hollow spherical porous anode materials for high performance lithium batteries.

Solvothermal self-assembly of magnetic Fe3O4 nanochains by ethylenediamine functionalized nanoparticles for chromium(VI) removal

In this study, one-dimensional amino-functionalized magnetic Fe3O4 nanochains (MNCs) consisting of self-assembled Fe3O4 nanoparticles (NPs) were synthesized via a facile one-pot solvothermal route at 180 °C using FeCl3·6H2O as the iron source and ethylenediamine as the surfactant without the use of any external magnetic fields or templates. The synthesized MNCs consist of nanospheres with a diameter of 120 nm assembled from Fe3O4 NPs and have good water dispersibility with a high Brunauer–Emmett–Teller surface area (44.028 m2 g−1). The magnetic measurements revealed the superparamagnetic nature of the as-prepared MNCs with a saturation magnetization of 70.9 emu g−1 at room temperature. The nanochain formation mechanism was proposed as a magnetic dipole–dipole interaction and caused by the effects of the ethylenediamine surfactants. These MNCs were confirmed to be efficient adsorbents for chromium(VI) removal. The adsorption isotherm conformed to the Langmuir model at a Cr(VI) ion concentration higher than 40 mg L−1, and the maximum removal capacity was 60.25 mg g−1 at a solid-to-liquid ratio of 1:1000 g/mL.

One-pot solvothermal synthesis of Co1−xMnxC2O4 and their application as anode materials for lithium-ion batteries

A facile one-pot solvothermal route has been developed to synthesize phase pure MxC2O4⋅2H2O (M=Mn, Co; 0<x⩽1) microstructures without employing any hard/soft template and their electrochemical performance in lithium-ion batteries has been systematically investigated. Morphology, microstructure and composition of the synthesized materials are characterized by field emission-scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. Anhydrous micron-sized MnC2O4 and CoC2O4 exhibits specific reversible discharge capacity of ∼800 and 950mAhg−1 respectively, at 1C-rate. MnC2O4 exhibited good cycling stability while CoC2O4 showed severe capacity fading phenomenon after 40 cycles, thereafter attaining 400–600mAhg−1 for all C-rates. Interestingly, mixed solid solution having Co0.52Mn0.48C2O4 composition improved the specific reversible discharge capacity to a stable value of ∼1000mAhg−1 (1C-rate), which is one of the highest reported values for such oxalates. The cycling stability of this mixed metal oxalate is remarkably better than its individual constituents at most C-rates. The Mn2+ substitution into CoC2O4 lattice has led to the synergistic modification of the electrochemical performances, thus making it a promising anode candidate for future LIBs.

Fabrication of γ-MnS/rGO composite by facile one-pot solvothermal approach for supercapacitor applications

γ-MnS/reduced graphene oxide (γ-MnS/rGO) composite was successfully fabricated via a facile one-pot solvothermal route using graphene oxide (GO), thioacetamide (TAA, CH3CSNH2) and MnCl2·4H2O as reactants. It reveals that TAA plays an important role in reducing GO and sulfurizing γ-MnS. The synthesized composite was characterized via X-ray diffraction and scanning electron microscopy for structural and morphological studies. Electrochemical performance was also investigated through cyclic voltammetry and galvanostatic charge–discharge. As for the application of supercapacitors, the γ-MnS/rGO composite shows a great value of 802.5 F g−1 at a current density of 5 A g−1. Furthermore, the capacitance of γ-MnS/rGO has no decrease of its initial values after 2000 cycles. The galvanostatic charge–discharge curve demonstrates the ideal capacitive behavior of γ-MnS/rGO composite electrodes.

One-pot solvothermal synthesis of ZnFe2O4 nanospheres/graphene composites with improved lithium-storage performance

We report a facile one-pot solvothermal route for synthesizing ZnFe2O4/graphene nanocomposites. XRD, SEM and TEM results demonstrate that ZnFe2O4 nanospheres with a size of about 100–200nm are uniformly dispersed on graphene nanosheets. Each ZnFe2O4 nanosphere is assembled by many nanoparticles around 10nm. When evaluated as anode for Li-ion batteries, ZnFe2O4/graphene nanocomposites deliver a first discharge capacity of 1400mAhg−1 and remain a reversible capacity up to 704.2mAhg−1 after 50 cycles. ZnFe2O4/graphene nanocomposites also exhibit ameliorative rate capacity of 271.8mAhg−1 at the current of 800mAg−1, which can recover to 814mAhg−1 when the current density is reduced back to 100mAg−1. The enhanced electrochemical performances of the nanocomposites are ascribed to the confining and conducting effects of graphene and the synergistic effects between the conductive graphene and ZnFe2O4 nanospheres.

One-pot synthesis of Ag@Fe3O4/reduced graphene oxide composite with excellent electromagnetic absorption properties

A ternary composite of Ag@Fe3O4/reduced graphene oxide (RGO) was synthesized by a facile one-pot solvothermal route and the electromagnetic absorption properties of the composite were investigated. The structure and morphology of the composite were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy and scanning electron microscopy. Interestingly, plenty of Ag/Fe3O4 core/shell particles are well-distributed on the surface of graphene nanosheets. The magnetic hysteresis measurement reveals the ferromagnetic behavior of the composite at room temperature. The electromagnetic absorption properties show that the maximum reflection loss of Ag@Fe3O4/RGO is up to −40.05dB at 11.9GHz and the absorption bandwidth with the reflection loss below −10dB is 3.1GHz (from 9.4 to 12.5GHz) with a thickness of 2mm. The absorption bandwidth with the reflection loss below −10dB is up to 13.5GHz with a thickness in the range of 1.5–5.0mm. The remarkable electromagnetic absorption properties of Ag@Fe3O4/RGO composite can be attributed to the multiple absorbing mechanisms. It is believed that such a composite could serve as an attractive candidate for electromagnetic absorber.

An easy one-pot solvothermal synthesis of poorly crystalline solid ReS2/C microspheres

Dense microspheres consisting of poorly crystalline ReS2 embedded in carbon were synthesized with a high yield via a facile one-pot solvothermal route, by reacting dirhenium decacarbonyl, elemental sulfur and an aromatic solvent (benzene, toluene or p-xylene) for 24 h at 180 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR) techniques were used to characterize the samples. The resulting microspheres were dense, with average diameters between 0.79 and 1.40 μm, had smooth surfaces and were constructed of ReS2 sheet-like structures with 4.5–9.8 wt % of structural amorphous carbon, which is retained as a textural stabilizer after calcination at 800 °C. The synthesis was repeated using isopropanol and cyclohexane, whose products were agglomerated grains and botryoidal quasi-spherical particles, respectively. A possible formation mechanism of ReS2/C microspheres was preliminarily presented, in order to clarify the mechanistic differences between the rhenium carbonyl and other transition metal carbonyls used in similar syntheses.

TiO2 nanocrystals/graphene hybrids with enhanced Li-ion storage performance

TiO2 nanocrystals/graphene hybrids (TiO2-G) with ultrafine TiO2 nanocrystals (~7 nm in size) conformally coated on ultrathin graphene nanosheets (~ 2 layers thick) were successfully prepared via a facile one-pot solvothermal route under mediated conditions. With the feature of large surface area, abundant mesopores and high thermal stability, the TiO2-G nanohybrids exhibited large reversible Li-ion storage capacity with excellent cycling stability (629 mAh·g−1 after 400 cycles at a current of 60 mA·g−1) and good rate capability (184 mAh·g−1 at a current density of 3 A·g−1) due to the synergetic effects and strong interactions between the components, showing great promise in applications for advanced energy storage devices.

Uniform iron oxide hollow spheres for high-performance delivery of insoluble anticancer drugs

As an intrinsic characteristic of many anticancer drugs, low solubility in physiological conditions limits the usage of these active ingredients in clinics. To overcome this bottleneck, we attempt to design and construct a high-performance magnetic-targeted delivery system based on uniform iron oxide hollow spheres. Via a facile one-pot solvothermal route, well-defined iron oxide hollow spheres were prepared with inexpensive inhesion. Compared with previously reported mesoporous Fe3O4 nanoparticles, our iron oxide hollow spheres have a larger void space giving the structures a higher storage capacity for guest molecules. In our present work, camptothecin (CPT) was selected as a model insoluble anticancer drug to confirm the efficiency of drug-loading and chemotherapy in vitro. Detailed anticancer efficacy was further investigated by using MTT assays and microscope imaging methods, indicating that these iron oxide hollow spheres are promising for insoluble drug delivery.

Controllable synthesis of plasmonic Ag/AgBr photocatalysts by a facile one-pot solvothermal route

Plasmonic photocatalysts Ag/AgBr composites were synthesized by a facile one-step solvothermal route. Unlike the traditional photoreduction method, metallic Ag in the present work was in situ anchored on the surface of AgBr by reducing radicals created through the thermal process. The structures (e.g., particle size, composition, and dispersion) of metallic Ag nanoparticles could be well controlled by simply changing the reaction temperature and solvent. The as-prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectra (DRS). The as-prepared Ag/AgBr composites exhibited excellent photocatalytic efficiency for the degradation of azo dye methyl orange (MO), phenol, and 2-chlorophenol under visible light irradiation. It was found that the activity was highly dependent on the particle size, composition and the dispersing extent of Ag nanoparticles. The photocatalytic mechanism was studied by radical-trapping experiments and the photoluminescence (PL) technique with terephthalic acid, and the results indicated that O2- and h+ played great roles in the rapid degradation of organic pollutants under visible light irradiation.