Facile One-step Solvothermal Process Research Articles

Solvothermal growth of silver-doped vanadium pentoxide microurchins as a cathode material for all-solid-state asymmetric supercapacitors

This study aims to improve the electrochemical properties of vanadium pentoxide by inserting silver cations into the vanadium oxide lattice. The porous silver-doped V2O5 (Ag-V2O5) microurchins were grown via a facile one-step solvothermal process. The enhanced mesoporosity and interlayer d-spacing upon silver-doping, as confirmed by Brunauer–Emmett–Teller (BET) and X-ray diffraction analyses, played an important role in facilitating the intercalation/de-intercalation of electrolyte ions and thus enhancing the capacitive performance of V2O5. The Ag-V2O5 electrode delivered a superior capacitance of 535.6 F/g at 0.5 A/g and a higher rate capacity of 78.8% in non-aqueous lithium perchlorate electrolyte compared to sodium perchlorate electrolyte. Furthermore, the specific capacitance of V2O5 was remarkably increased by ∼56% upon 5.33 at% Ag-doping. An all-solid-state asymmetric supercapacitor (ASC) was fabricated using Ag-V2O5 as the cathode, activated carbon cloth as the anode, and LiClO4-loaded poly(acrylonitrile-co-1-vinylimidazole-co-itaconic acid) as a solid electrolyte. The ASC was stably operating in a wide potential window of 0–1.6 V and delivered a high energy of 53.8 Wh kg−1. Most importantly, the ASC exhibits a slow self-discharge rate with only 7.7% voltage loss after 17 h when charged at 1.6 V. Hence, these impressive electrochemical performances of Ag-V2O5 make it a promising cathode material for next-generation supercapacitors.

Direct growth of hierarchically SnS2 layered nanostructure on nickel foam for high-performance solid-state supercapacitors

SnS2 is a promising candidate for an electrode material in lithium-ion batteries and photocatalysts due to its high accessible surface area and significant interlayer nanostructure. Here, we have synthesized hierarchically SnS2 layered nanostructure developed on nickel foam through a facile one-step template-free solvothermal process. FESEM images show the two-dimensional (2D) layer structure of SnS2 arranged in a flower petallike configuration. Further, the electrochemical properties of hierarchically SnS2 were investigated in 1 M KOH electrolyte for supercapacitor (SC) implementation. Synthesized SnS2 electrode material shows excellent specific capacitance of 604F g−1 at 1 mVs−1 and better cyclic stability of 86.2 % over 3000 cycles because the unique layered nanostructure increases the active sites and ion/electron transfer at the electrolyte/electrode interface. The hierarchically structured SnS2 electrode and its potential practical applications were tested by fabricating an SSC device to effectively light a commercial light-emitting diode (LED). This research shows that layered 3D SnS2 electrodes are a promising technology for sustainable energy storage applications. The above results indicated that hierarchically SnS2 with a 2D layered structure has a huge capability as an electrode material for high-performance SC applications and a promising potential for future energy storage devices.

Facile one-step preparation of Co and Ce doped TiO2 in visible light PMS activation for PAHs degradation

In this work, Co and Ce doped TiO2 (CoCeTi) with low content of Co and Ce was successfully prepared by a facile one-step sol-gel solvothermal process for activating Peroxymonosulfate (PMS) to degrade Polycyclic aromatic hydrocarbons (PAHs). The phenanthrene degradation rate was 98.2% effectively in 15 min by CoCeTi (50.0 mg/L) activation PMS (0.50 mmol/L) under visible light. SO4•−, O2•–, h+ and 1O2 were verified as the dominant reactive species for PAHs degradation. The collective effect of CoCeTi, PMS and visible light irradiation has been discussed. The possible phenanthrene degradation pathway was proposed through intermediates analysis. CoCeTi composed of Co3O4, CeO2 and TiO2 was confirmed. Outstandingly, CoCeTi/PMS/visible light system has very low cobalt (0.036 mg/L) and cerium (0.27 mg/L) leaching. Due to CoCeTi having good activated PMS properties and other excellent characteristics, it has potential application for PAHs or other organic pollutants degradation.

In Situ Ni2P-Integrated Black Phosphorus Nanosheets for Efficient Photocatalytic H2 Evolution

The charge-carrier separation efficiency is one of the important factors for a high photocatalytic performance. Herein, a nickel phosphide (Ni2P) cocatalyst chemically bonded to black phosphorus (BP) nanosheets (0D/2D Ni2P/BP) has been synthesized by a facile one-step solvothermal process, using the commercial red phosphorus (RP) as a precursor material. RP is used not only to synthesize BP but also to form in situ Ni2P as a cocatalyst for the host BP photocatalyst. The in situ grown Ni2P on BP nanosheets leads to the creation of a Ni–P covalent bond, which enhances the charge separation as well as material stability. Thus, the developed nanocomposite was found to be efficient toward photocatalytic H2 production at a rate of 406.08 μmol·g–1·h–1 under sunlight with high apparent quantum yields of around 48.45 and 7.90% at 360 and 400 nm, respectively. Notably, the Ni2P/BP composite is found to be more efficient compared to the Pt/BP composite. As confirmed by the comparative study between the chemically and physically loaded Ni2P nanocomposites, the Ni–P bonds enhance the interfacial charge-carrier separation at the interface of BP and Ni2P, which ultimately increase the lifetime of the photogenerated electrons and improve the photocatalytic performance. The obtained results demonstrate that the established in situ one-step solvothermal synthesis strategy can be viable for the scalable synthesis of the developed materials for the large-scale H2 production under solar light.

One-step synthesis of CdS hierarchical microspheres and its ethanol sensing property

The high concentration (>100 ppm) ethanol gas that CdS sensors detect commonly results in saturation problem. In this work, CdS hierarchical microspheres with the diameter of 5 µm–10 µm assembled with abundant nanosheets are prepared by a facile one-step solvothermal process. The specific surface area of the CdS material was 27.04 m2·g−1, which can provide a certain amount of active sites for the target gas and the adsorbed oxygen. In addition, the sensor fabricated by CdS hierarchical microspheres exhibits enhanced sensitivity for C2H5OH to 10 ppm at the optimum operating temperature of 200 °C. The sensor also shows good repeatability, excellent stability and fast response/recovery time of 2.8 s/4.8 s for C2H5OH to 100 ppm. Meanwhile, the good linear relationship of the sensor under wide concentration range of 10 ppm–500 ppm for C2H5OH demonstrates outstanding humidity resistance. The possible C2H5OH-sensing mechanism of CdS hierarchical microspheres is discussed on the basis of XPS analysis.

High performance Flower-Like Mn3O4/rGO composite for supercapacitor applications

• The flower-like Mn 3 O 4 /rGO composite was prepared by a facile one-step solvothermal process. • The as-prepared Mn 3 O 4 /rGO material exhibits a high specific capacitance of 947F g −1 at a current density of 1 A g −1 and excellent capacitance retention of 88.1% after 4000 GCD cycles at 10 A g −1. • The addition of rGO effectively improved the conductivity of Mn 3 O 4 and providing more buffer space for the electrochemical reaction of Mn 3 O 4 , • The flower-like nanostructure allows for more active sites and a shorter electrolyte ion diffusion pathway. Mn 3 O 4 has attracted great interest due to its pseudocapacitive properties, low cost, and environmental friendliness. However, the low conductivity and high-volume expansion limit its application to supercapacitors. In this research, a flower-like Mn 3 O 4 /reduced graphene (rGO) electrode material was obtained by a one-step solvothermal process. The as-prepared Mn 3 O 4 /rGO electrode exhibits a high capacity of 118.375 mAh g −1 at a current density of 1 A g −1 and an excellent cycle ability of 88.1% after 4000 cycles at a current density of 10 A g −1 . The high performance of the Mn 3 O 4 /rGO electrode can be attributed to the hierarchical structure and improved charge transfer capability as well as buffer space for the volume expansion by the addition of rGO. The nanoflower-like structure of Mn 3 O 4 /rGO provides a more active sites and short ion transport pathway during the redox reaction. The results provide an efficient way of improving the electrochemical performance of Mn 3 O 4 and show its great potential in SC applications.

Rime-like carbon paper@Bi2S3 hybrid structure for efficient and broadband microwave absorption

Although metal chalcogenides have been widely utilized as microwave absorbers, it remains a challenge for them to achieve efficient and broadband absorption performance with low filler content. Herein, a series of rime-like carbon paper@Bi2S3 hybrid structures are manufactured by a facile one-step solvothermal process, whose morphology and microwave absorption properties also can be easily adjusted by the dosage control of raw materials. The Bi2S3 clusters are grown densely on the surface of carbon paper fibers, like the rime in winter. The collocation of carbon paper and Bi2S3 is beneficial to impedance matching and synergistically enhances microwave absorption capability based on various attenuation mechanisms, including interfacial/dipolar polarization loss, conduction loss, and multiple reflection. At a low filler content (only 5 wt%), the optimal reflection loss among these composites is −56.63 dB at 8.84 GHz with 3.3 mm thickness, and the broadest efficient absorption bandwidth is 7.32 GHz with a thickness of 2.4 mm, covering the whole Ku band. By adjusting the thickness, the total covered frequency range reaches 13.36 GHz (83.5% of 2–18 GHz). The as-prepared materials have unique microstructure and exhibit strong and broadband absorption performance with thin thickness and low filler content, enlightening future exploration of metal chalcogenides on high-quality microwave absorbers.

A novel and green heterogeneous photocatalytic system (Ca0.01Fe2.99O4/CaTiO3 nanocomposite): Protocol synthesis, characterization, and study of photo-decoloration activity

In our work, we have synthesized effective Ca0.01Fe2.99O4/CaTiO3 nanocomposite (as-called coexistence structure) for visible-light photocatalysis. Our coexistence structure composed of magnetic n-type semiconductor Ca0.01Fe2.99O4 (CF) and p-type semiconductor CaTiO3 (CT) was successfully synthesized with various molar ratios (1:1, 1:2, 1:4 and 1:6) via a facile one-step solvothermal process. The good interaction between nanosphere of CF and nano rectangular prism of CT were determined by: XRD, FE-SEM with false colored scanning electron microscope (SEM) images, UV–Vis, DRS, TEM, FT-IR, VSM, XPS and EDX methods. Photocatalytic activities of all prepared samples were examined by decoloration of methylene blue (MB) solution as a model dye under visible light irradiation. Results clearly show that the molar ratio (1:6) of Ca0.01Fe2.99O4/CaTiO3 nanocomposite (CF/CT NC) exhibited the efficient photo-induced elimination of the MB that were confirmed with by using UV–Vis. spectroscopy. The photo-electrochemical tests show that the photocurrent density of CF/CT NC was better than bare oxides. Furthermore, the stability and the greenness of NC (1:6) was tested by cyclic experiments and external magnetic, respectively. Based on all outcomes, our heterogeneous photocatalytic system affords a platform to realize the environment improvement.

Hierarchical Bi-doped BiOBr microspheres assembled from nanosheets with (0 0 1) facet exposed via crystal facet engineering toward highly efficient visible light photocatalysis

A facile one-step solvothermal process was used to synthesize Bi-doped BiOBr microspheres with mainly the (0 0 1) crystal facet exposed (Bi/BiOBr-001-m), which exhibited enhanced photocatalytic performance. The photocatalytic performance and stability of the obtained Bi/BiOBr-001-m photocatalyst for Cr(VI) photoreduction removal and rhodamine B (RhB) photooxidation degradation were significantly better than those of pure BiOBr and Bi-doped BiOBr microspheres. The enhanced performance is ascribed to the retarding effect of photoinduced electron–hole recombination caused by Bi doping and the predominant (0 0 1) crystal plane composite structure. The photocatalytic performance could be further boosted by the adsorbed RhB owing to the dye sensitization effect. This work provides a reference for effectively improving the photocatalytic performance by combining crystal facet engineering and element doping.

Synthesis of CoTe nanowires: a new electrode material for supercapacitor with high stability and high performance

Highly dispersed CoTe electrode material were successfully prepared by using a facile one-step solvothermal process without any surfactants. Compared with the conventional hydrothermally prepared irregularly-shaped CoTe, a regular nanowire-formed CoTe can be obtained by a solvothermal process using ethylene glycol as a solvent. The prepared CoTe nanowire electrode can exhibit a relatively high specific capacity of 643.6 F g−1 at a current density of 1 A g−1 and remarkable cyclic stability with 76.9% of its specific capacitance retention after 5000 cycles at a high current density of 5 A g−1. Besides, even at the high current density of 20 A g−1, the specific capacitance of CoTe nanowire electrode still has 90.2% retention relative to 1 A g−1, showing an excellent rate performance. In order to enlarge the potential window to increase the energy density, an asymmetric supercapacitor (ASC) is assembled by applying CoTe nanowires and activated carbon as the positive electrode and the negative electrode in 3 M KOH, which can enlarge the operating voltage to as high as 1.6 V, and shows a specific capacity of 92.5 F g−1 with an energy density of 32.9 Wh kg−1 and power density of 800.27 W kg−1 at 1 A g−1, and even after 5000 cycles of charge/discharge at 5 A g−1, the ASC still retains 90.5% of its initial specific capacitance, showing excellent cycle stability.

Crumpled Quaternary Nanoarchitecture of Sulfur-Doped Nickel Cobalt Selenide Directly Grown on Carbon Cloth for Making Stronger Ionic Soft Actuators.

A novel crumpled quaternary sulfur-doped nickel cobalt selenide nanoarchitecture grown on carbon cloth (S-(NiCo)Se/CC) has been successfully synthesized as an electrode material for high-performance ionic polymer-carbon cloth composite (IP-CCC) actuators. A facile one-step solvothermal process has been introduced here to synthesize S-(NiCo)Se/CC, resolving the time-consuming, complicated, and costly problems of existing methods. Taking advantage of the outstanding electron transport kinetics and three-dimensionally interconnected nature of the transition-metal chalcogenide structure, the hybrid carbon cloth electrode with quaternary sulfur-doped selenide nanoarchitectures exhibits low electrical resistivity (3 times lower than that of bare CC), high areal capacitance (409 mF/cm2), and excellent cycle stability (over 4000 cycles). Moreover, due to the synergistic effect between S-(NiCo)Se and a carbon cloth substrate, the S-(NiCo)Se/CC electrode-based actuator exhibits high blocking force (38.5 mN), 6 h durability, and large bending strain (0.47%). Compared with other actuators reported in the literature, the S-(NiCo)Se/CC electrode-based actuator shows much higher normalized blocking force, leading to opening of new potential applications in the field of next-generation soft electronics. Moreover, stacked multiple IP-CCC actuators in parallel exhibit an exceptional blocking force of 0.174 N under direct current 4 V.

Synthesis of N-doped mesoporous TiO2 by facile one-step solvothermal process for visible light photocatalytic degradation of organic pollutant

Utilization of visible-light in photocatalysis is one of the key aspects of achieving effective application. Non-metal doping solely is often not adequate to give a genuinely practical solution because of challenging separation process. Here, we demonstrate the facile synthesis of modified TiO2 by non-metal N-doping and surface modification through a one-step solvothermal method. Under this process, both N-dopant and CTAB could be introduced in one process thus creating N-doped mesoporous TiO2 after template removal using calcination. N2 physisorption indicated high specific surface area up to 148.60 m2/g. Furthermore, the adsorption-desorption isotherm curve exhibited type IV thus confirming the presence of a mesoporous structure, with H1 and H2 hysteresis loop for slow and fast ramp calcination, respectively. Various characterizations were also carried out to explain the possible band-gap reduction mechanism which leads to the workability extension of the as-synthesized photocatalyst. Faster and superior settling capability was shown qualitatively using static settling test. The performance of the modified photocatalysts showed improved performance in methylene blue (cationic dye) and methyl orange (anionic dye) degradation under visible light (λ > 400 nm) as compared to other commercially available TiO2 photocatalysts. In conclusion, facile modifications introduced in this research proved to bring constructive effect, establishing better photocatalyst with effective utilization of visible light and also simple to retrieve catalyst.

Citric acid induced W18O49 electrochromic films with enhanced optical modulation

Electrochromic materials exhibit promising applications in energy-saving fields for their ability to control heat from outdoors. Nanostructured W18O49 has drawn attention for its one-dimensional structure to transfer charge efficiently as a remarkable electrochromic material. W18O49 bi-layer films were fabricated through a facile one-step solvothermal process with citric acid as a chelating agent. The addition of citric acid improved the deposition on the substance, and a nanostructured film with a denser layer at the bottom and a tussock-like upper layer was obtained. The bi-layer film exhibited an enhanced optical modulation of 68.7%, a coloration efficiency of 82.1 cm2/C with stability over 400 cycles, and fast response times (1.4 s and 2.3 s for bleaching and coloring), with expectation to be applied in the electrochromic field.

1T@2H-MoSe2 nanosheets directly arrayed on Ti plate: An efficient electrocatalytic electrode for hydrogen evolution reaction

Few-layered MoSe2 nanosheets with mixed 1T/2H phase were successfully arrayed on a Ti substrate (forming 1T@2H-MoSe2/Ti) through a facile one-step solvothermal process. After testing different synthesis conditions, it was found that the optimal process involves a temperature of 200 °C and a reaction time of 12 h. Structural characterizations reveal that the morphology of 1T@2H-MoSe2 consists of edge-terminated nanosheets with one to five layers, composed of a mixed 1T/2H phase dominated by the 1T one. The 1T@2H-MoSe2/Ti electrode shows excellent HER catalytic activity, with a small onset potential (−120 mV vs. reversible hydrogen electrode, RHE) and an electrode potential of only −133 mV (vs. RHE) to achieve a current density of 20 mA·cm−2. This excellent electrocatalytic activity is due to the synergistic effects of 1T metallic phase, few-layered nanosheet morphology, and direct growth of 1T@2H-MoSe2on the Ti substrate. In addition, the 1T@2H-MoSe2/Ti electrode shows excellent stability towards long-term electrolysis. This is due to the long-term stability of the valence states of Mo and Se, as shown by post-electrolysis X-ray photoelectron spectroscopy analysis.

Effects of sodium oleate on synthesis and photocatalytic activity of Bi2WO6/Bi2O3@RGO

In this study, the effects of sodium oleate on synthesis of Bi2WO6/Bi2O3 loaded reduced graphene oxide photocatalyst was studied. The as-prepared composites were characterized by X-ray diffraction, Fourier transform infrared, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance and photoluminescence spectroscopy. The results suggested that addition of sodium oleate not only promoted synthesis of Bi2O3, but also enhanced the reduction of GO to graphene. When the amount of sodium oleate was 4 mol (Bi:SO = 1:1), Bi2WO6/Bi2O3@RGO to the best visible-light photocatalytic activity can be synthesized by a facile one-step solvothermal process without further reduction reaction. Hence, it indicated that sodium oleate could affect the synthesis of the as-prepared composites and the photocatalytic activity for degradation of RhB. This study did provide not only a facile method to synthesize Bi2WO6/Bi2O3@RGO, but also a method to reduce graphene oxide to graphene.

Solvothermal evolution of red palygorskite in dimethyl sulfoxide/water

Abstract Red clay deposit with palygorskite (Pal) as the main component is abundant on the earth, but it is not yet fully utilized in industrial fields because of its deep color. In this paper, we employed a facile one-step solvothermal process to treat red Pal using water, dimethyl sulfoxide (DMSO) and DMSO/water as solvents and studied the effect of this process on the structure, physico-chemical characteristics and color of red Pal. It was revealed that the brick-red Pal still remain its color unchanged after solvothermal reaction in water or DMSO solvent, but it converted to white after reaction in dimethyl sulfoxide (DMSO)/water mixture. When the volume ratio of DMSO to water is 2:1, the product has the best whiteness of 83.3%. The associated minerals such as quartz, feldspar and muscovite did not change significantly and the rod-like crystalline morphology of Pal still remains intact after solvothermal reaction. The leaching of Fe(III) in Pal, the dissolution of α-Fe 2 O 3 and the reduction of Fe(III) by the dimethyl sulfide (the reaction product of DMSO with water) to Fe(II) contributed to the conversion of red Pal to white one. The conversion of brick-red Pal to white would lay a foundation for the applications of deep-colored clay minerals in the fields of chemical industries and composite materials.

Hierarchical α-Ni(OH)2 Composed of Ultrathin Nanosheets with Controlled Interlayer Distances and Their Enhanced Catalytic Performance.

Hierarchical α-Ni(OH)2 assembled of ultrathin nanosheets with the intercalation of diatomic alcohol molecules were synthesized via a facile one-step solvothermal process. The assembly structure avoided the agglomeration of ultrathin nanosheets while retaining their atomic-scale thickness and high surface area. The intercalation of the diatomic alcohol molecules into the transition-metal layers provided larger interlayer spacing and more exposed active sites, which guaranteed the high activity of the α-Ni(OH)2. The as-obtained hierarchical α-Ni(OH)2 exhibited excellent catalytic performance in the reduction of p-nitrophenol, with a maximum reaction rate constant (k) of 6.23 × 10-3 s-1 and a super high activity factor K (K = k/m) of 216.69 s-1 g-1. The layer spacing played the most important role in the reaction, and the catalytic efficiency increased greatly with the increase of the layer spacing of the α-Ni(OH)2. This design concept and synthetic method can also be extended to the production of a wide variety of hierarchical catalysts for other reactions.

One-step synthesis and magnetic properties of Ni-Fe3O4@PI core–shell composite microspheres

Nickel(Ni)-iron(III) oxide(Fe3O4)@polyimide (PI) composite microspheres were successfully prepared from poly(amic acid) triethylammonium salts and a mixture of Fe(III) and Ni(II) via a facile one-step solvothermal process. Furthermore, the formation mechanism of the composite microspheres has been investigated. The morphology and the structure of the samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and infrared spectroscopy, respectively. It was determined that PI could be successfully coated on the surface of the magnetic microspheres. Based on the results obtained from thermo-gravimetric analysis and vibrating sample magnetometer curves, it was found that the composite microspheres exhibit an excellent thermal stability. The prepared sample, coined NiFe@PI-4, with higher weight content of iron particles in the polymer matrix, showed improved magnetic properties (saturation magnetization = 57.1 emu/g) due to the high saturation magnetization of Fe3O4 and excellent dispersion effects of polyethylene glycol on the nanoparticles in solution.

One-Step Synthesis of Silver Nanoparticle-Decorated Hydroxyapatite Nanowires for the Construction of Highly Flexible Free-Standing Paper with High Antibacterial Activity.

A highly flexible and free-standing paper with high antibacterial activity made from silver nanoparticle (AgNP)-decorated ultralong hydroxyapatite nanowires (HAPNWs) is reported. The HAPNWs@AgNPs nanocomposites were obtained from a facile one-step solvothermal process and utilized for the construction of highly flexible and free-standing inorganic paper through a simple vacuum-filtration procedure. The structure and properties of the HAPNWs@AgNPs paper were characterized in detail. Scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs show that AgNPs are highly dispersed and stabilized in the nanocomposite and exhibit a narrow particle size distribution. The effects of the concentration of silver nitrate, solvothermal temperature and time on the product were systematically investigated. This method is simple, convenient and reproducible. The as-prepared HAPNWs@AgNPs paper shows long-time sustained silver-ion release, high antibacterial activity against both Gram-negative and Gram-positive bacteria, and good biocompatibility. Overall, this work provides a novel pathway for the preparation of a new type of highly flexible, free-standing and antibacterial inorganic paper made from silver nanoparticle-decorated hydroxyapatite nanowires for various applications, as a promising functional biomaterial.

One-Step Fabrication of Magnetic Carbon Nanocomposite as Adsorbent for Removal of Methylene Blue

Magnetic Fe3O4@C nanocomposites with well-defined core@shell structure were synthesized via a facile one-step solvothermal process using ferrocene as both iron and carbon resource in the presence of hydrogen peroxide (H2O2). The as-prepared Fe3O4@C nanocomposites were employed as adsorbent materials for removal of methylene blue (MB) from aqueous solution. Several experimental parameters, including contact time, acidity of the solution, and initial MB concentration were investigated. The result showed that the equilibrium uptake of MB was related to the MB initial concentration as well as acidity of the solution. The adsorption kinetics of MB was dominated by the pseudo-second order reaction model. Significantly, the synthesized Fe3O4@C nanocomposites could be easily isolated from the adsorption system after adsorbing MB and showed prominent reusability. All results indicated that the prepared Fe3O4@C composites had the potential to be used as adsorbents for the removal of dye pollutant from wastewater.