Facile One-pot Hydrothermal Synthesis Research Articles

A novel carbon-decorated hollow flower-like MoS2 nanostructure wrapped with RGO for enhanced sodium-ion storage

A novel composite nanomaterial that consisting of few-layer MoS2 modified by pyrolyzed conductive carbon was self-assembled into hollow flower-like nanostructures, and wrapped with the reduced graphene oxide (RGO) networks via a facile one-pot hydrothermal synthesis route. This unique nanostructure of the sample possesses large specific surface area and expanded interlayer, which could provide more adsorption sites for Na+ and better buffer the volume change in Na+ insertion and deinsertion. Moreover, by incorporated with carbonaceous materials involving both amorphous carbon and RGO, the limited electrical conductivities and structural stability of MoS2 can be improved effectively, meanwhile the aggregation of 2D layer materials is also relieved, promoting the fluent transport of sodium ion and leading to greatly enhanced electrochemical performances. When evaluated as an anode material for sodium-ion batteries, the as-obtained electrode exhibits the highly reversible capacities (891 mAh g−1 at 50 mA g−1) and favorable cyclability (637 mAh g−1 at 50 mA g−1 for 50 cycles). These results, combined with our experimental design strategy, provide an efficient approach to enhance the cycling property of MoS2 and congeneric 2D electrode materials.

Facile one-pot hydrothermal synthesis of particle-based nitrogen-doped carbon spheres and their supercapacitor performance

Particle-based nitrogen-doped carbon spheres (PNCSs) were prepared via a hydrothermal and carbonization route and PNCSs-1.2 demonstrated an enhanced supercapacitor performance.

Ammonium Ions Intercalated 1T-MoS2 for Enhanced Electrochemical Hydrogen Production

Molybdenum disulphide (MoS2), a 2D layered transition metal dichalcogenide (TMDC) is being studied as an effective catalyst for Hydrogen Evolution Reaction (HER) in electrochemical water splitting. Optoelectronic properties of nanostructured MoS2 make them a potential materials for energy conversion and energy storage.[1-2] MoS2 exhibits 2 major stacking polytypes, 2H and 1T based on their coordination symmetry, where 2H is trigonal prismatic (D3h), 1T exists in octahedral coordination (Oh). 2H phase is a semiconductor where sulfur edges are only active, but 1T phase is metallic with both edge and basal planes active for HER. However, 1T is metastable in nature and easily converted into 2H [3]. To enhance the HER rate, alkali metals (Na, K, Li) are intercalated into 1T MoS2. The intercalation of alkali metals (Li, Na, Mg) can increase the d-spacing and electronic conductivity between interlayer and reduce the barrier to the diffusion of large-sized ions.[4] Here we have reported a facile one-pot hydrothermal synthesis of 1T-MoS2 at various temperatures (120-200oC) to perform as effective catalysts for HER. The d-spacing of inter-layer expanded 1T-MoS2at various temperatures are 0.92nm. 1T MoS2 was prepared by hydrothermal method at various temperatures (120-200oC) using ammonium molybdate tetrahydrate and thiourea in aqueous solution as precursors. The calculated molar ratio of Mo:S in the solution was 1:4. Ammonium ions released from thiourea and ammonium molybdate intercalated into the layers of MoS2 which eventually increases the d-spacing. The crystallinity and phases of the MoS2 sample were analyzed using X–ray diffraction. In contrast to bulk 2H phase, the ammonium ion intercalated 1T phase shows two new peaks at 9.5o (002) and 18.95o (004) with a d-spacing of ~9.27Å and 4.67Å, respectively. The ammonium ion intercalation increases the d-spacing and thereby shifts in the (002) plane from 14.3o to 9.5o is observed. The change in the d spacing is 3.3 Å and matches with the size of hydrogen bonding diameter in ammonium ions (∼ 3.5 Å).[5] The crystallinity of the MoS2sample increased with increasing temperature. The sulfur composition is being further examined using X-ray photoelectron spectroscopy. The onset potential for HER decreases with increase in the crystallinity. The hydrogen evolution current also shows significant increase with increase in crystallinity. The enhanced interlayer spacing increases the diffusion of larger Hydronium ions into the layer which directly enhances the hydrogen evolution rate. Hydrogen evolution reaction mechanism is being studied using electrochemical studies such as Tafel polarization.

Monodispersed FeCO3 nanorods anchored on reduced graphene oxide as mesoporous composite anode for high-performance lithium-ion batteries

The development of advanced 1D/2D hierarchical nanocomposites for high-performance lithium-ion batteries is important and promising. Herein, monodispersed FeCO3 nanorods anchored on reduced graphene oxide (RGO) are prepared via a facile and efficient one-pot hydrothermal synthesis. The influence of RGO content on the morphology and electrochemical performances of the mesoporous FeCO3/reduced graphene oxide (FeCO3/RGO) composites are systematically studied. Optimized FeCO3/RGO composite shows good cycling stability. It delivers an initial discharge capacity of 1449 mAh·g−1 at the current density of 200 mA g−1 and maintained a capacity of 789 mAh·g−1 after 80 cycles. A moderate amount of RGO sheets can not only provide more conductive channels to improve the electrode conductivity, but also effectively buffer the large volume variation of FeCO3 during continuous charge/discharge process. The combination of FeCO3 nanorods with RGOs synergistically contribute to enhanced capacity and durability of the composite anode. It demonstrates that RGO anchored-FeCO3 nanorods should be an attractive candidate as anode material for high-performance lithium-ion batteries.

A facile one-pot hydrothermal synthesis of tin sulfide-decorated reduced graphene oxide nanoribbons and its sensing application for a flavanone naringenin

New electrode materials have been synthesized extensively with the aim of enhancing sensitivity and selectivity besides decreasing the overpotential of electrode reactions. Present work describes the design of a new one-pot hydrothermal route for the preparation of highly electroactive nanocomposite, SnS2 decorated reduced graphene oxide nanoribbons (designated as SnS2-rGONRs) for analytical and binding applications of a flavanone, naringenin (NAR). Electrode materials were characterized by XRD, Raman, TEM and AFM techniques. SnS2-rGONRs based electrochemical sensor was fabricated by drop casting of SnS2-rGONRs dispersion on GCE surface (SnS2-rGONRs/GCE). SnS2-rGONRs/GCE was utilized to explore the detailed electrochemistry of NAR and to unravel the mechanism of interaction of NAR with human serum albumin. About 50-fold enhancement in the electrochemical response of NAR was observed at SnS2-rGONRs/GCE compared to that noticed at bare GCE, suggesting that the interface SnS2-rGONRs has an excellent charge transfer capability. Influence of pH and scan rate was studied to explore the electrode kinetics of NAR. Under the optimized conditions, a linear relationship between the peak current and concentration of NAR was observed in the range of 0.49–56.6μM. Proposed electrode, SnS2-rGONRs/GCE was employed for the determination of NAR in analyte fortified biological samples. Binding characteristics viz., binding constant, stiochiometry and mode of interaction of NAR with drug carrier protein, human serum albumin (HSA) was also explored using the proposed sensor. Binding constant of NAR-HSA was found to be in the order of 104M−1 and one molecule of NAR was bound to one macromolecule of HSA.

Fabrication of ZnS Hollow Spheres and RGO-ZnS Nanocomposite Using Cysteamine as Novel Sulfur Source: Photocatalytic Performance on Industrial Dyes and Effluent

A facile one-pot hydrothermal synthesis of hollow ball-like ZnS nanostructures is reported using cysteamine, an ecofriendly sulfur source. Following similar protocol, a heterostructure of RGO-ZnS nanocomposite have been synthesized. The as-synthesized samples are structurally and optically characterized using different techniques. The photocatalytic activity of RGO-ZnS has been found to be ∼9% higher than that of ball-like ZnS nanostructures at a dose of 0.4 g/L. This result is attributed to the improved charge transport by hindering charge recombination of photoinduced excitons. One of the significant findings of this work is that the model anionic dye degraded better under alkaline condition with ZnS whereas the trend is reversed for RGO-ZnS composite. The removal efficiency of both the systems is allied with structural, morphological, and optical properties to understand the underlying mechanism of synthesis as well as photocatalysis process.

Facile hydrothermal synthesis of nanocomposites of nitrogen doped graphene with metal molybdates (NG-MMoO4) (M=Mn, Co, and Ni) for enhanced photodegradation of methylene blue

A facile one-pot hydrothermal synthesis of nanocomposites of nitrogen doped graphene with MnMoO4/CoMoO4/NiMoO4 is reported. The morphological and structural characteristics of prepared NG-MMoO4 nanocomposites have been characterized by Powder X-ray diffraction, Fourier transform vibrational spectroscopy, Scanning electron microscopy, Transmission electron microscopy and Thermal analysis. The molybdates are well-anchored and uniformly distributed on the surface of nitrogen doped graphene sheets. The nanocomposites exhibit excellent photocatalytic activity as demonstrated by photodegradation of methylene blue under Ultraviolet–Visible irradiation by using NG-MnMoO4 as catalyst.

Facile one-pot synthesized ordered mesoporous Mg-SBA-15 supported PtSn catalysts for propane dehydrogenation

A series of high-surface area and well-ordered mesoporous Mg-incorporated SBA-15 (xMg-SBA-15, x=0, 1, 2, 4 and 6) was prepared using a facile one-pot hydrothermal synthesis method. The resulting materials were used to disperse Pt, Sn particles and further studied the catalytic performance for propane dehydrogenation. The physicochemical properties of the supports and catalysts were characterized by XRD, N2 adsorption-desorption, FT-IR, TEM, NH3-TPD, XPS, H2-TPD and TG-DTA techniques. Compared with the sample synthesized by the impregnation method, the xMg-SBA-15 materials showed a better Mg species distribution and higher specific surface area. It was found that incorporation of appropriate amounts of Mg promoted the dispersion of metallic nanoparticles and facilitated the transfer of the carbon deposits from the active metal to the support. Such a modification of support not only enhanced the interaction of the Sn-support, but also stabilized the oxidation state of Sn species, leading to the improvement of catalytic activity and stability. The significant increases in conversion and selectivity were obtained on the modified catalysts with appropriate content of Mg. The best catalytic performances were obtained on PtSn/2Mg-SBA-15 catalyst with 2wt.% of magnesium, showing a higher than 98% selectivity toward propene at a 38.0% conversion of propane even after 6h reaction.

Highly active and durable methanol electro-oxidation catalyzed by small palladium nanoparticles inside sulfur-doped carbon microsphere

In this work, small palladium nanoparticles (Pd NPs) inside sulfur-doped carbon microsphere (S-CMS) were synthesized to achieve both high electro-catalytic activity and long durability for methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). The highly dispersed Pd NPs encapsulated in S-CMS with an architectural feature like the plum pudding model were obtained via a facile one-pot hydrothermal synthesis employing reduced glutathione (r-GSH) as both reducing and capping agents, followed by a simple carbonization procedure. The synthesized Pd NPs inside S-CMS was found to provide larger effective surface for MOR compared to commercial Pd/C. Mass activity 5.9 times higher than that of Pd/C was acquired, originating from the small size of Pd NPs and their interactions with the heteroatom-modified CMS coating. Due to the decreased agglomeration and dissolution, the proposed encapsulated Pd NPs also kept more stable during continuous start-stop operation, suggesting its great potential as an effective anode material to be used in DMFCs.

Uncapped nanobranch-based CuS clews used as an efficient peroxidase mimic enable the visual detection of hydrogen peroxide and glucose with fast response

Nanosized materials acting as substitutes of natural enzymes are currently attracting significant research due to their stable enzyme-like characteristics, but some flaws of these nanozymes, including their limited catalytic rate and efficiency, need to be remedied to enable their wider applications. In this work, we verify for the first time the catalytic behavior of uncapped nanobranch-based CuS clews as a peroxidase mimic. XRD, XPS, SEM, and TEM proofs demonstrate that high-purity CuS clews composed of intertwined wires with abundant nanodendrites outside are successfully produced via a facile one-pot hydrothermal synthesis approach, with thiourea as both the sulfion source and the structure-directing agent. The synthesized CuS can catalytically oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2 to trigger a visible color reaction with rapid response (reaching a maximum change within 5 min). The proposed CuS nanozyme exhibits preferable catalytic kinetics over natural horseradish peroxidase (HRP). This outstanding activity primarily results from the large surface area and rich sites exposed by the uncapped unique structure. Under optimized conditions, the fabricated sensing system provides linear absorbance (652 nm) changes in the H2O2 concentration range of 0.2˜130 μM, with a detection limit of as low as 63 nM. When coupled with glucose oxidase (GOD), the system is demonstrated to be capable of monitoring glucose in blood samples with excellent performance.

Facile one-pot hydrothermal synthesis and electrochemical properties of carbon nanospheres supported Pt nanocatalysts

One kind carbon nanosphere supported Pt nanocatalyst (Pt/CN-1) has been successfully synthesized by a facile one-pot hydrothermal synthesis using sucrose as carbon source and triblock pluronic copolymer P123 as reducer and stabilizer. The obtained Pt nanoparticles with an average diameter at 3.0 nm were uniformly distributed on the surface of the carbon nanospheres. The other kind Pt/CN-2 was prepared through the same route just in absence of P123, the carbon sphere was used as both carrier and reducer due to its reducing nature. Characterization demonstrated that the Pt/CN-2 was aggregated seriously without the protection of P123. The electrocatalytic tests indicated that the Pt/CN-1 nanocatalyst exhibited an enhanced electrocatalytic activity toward methanol oxidation in acidic media than that of Pt/CN-2 catalyst and commercial Pt/C catalyst. The promising synthetic method provides a new avenue to prepare carbon spheres supported Pt-based nanocatalysts used for direct alcohols fuel cells (DAFCs).

Facile Synthesis of CoSe<sub>2</sub> Nanoparticles and their Electrocatalytic Performance for Hydrogen Evolution Reaction

For more energy-efficient and economical hydrogen production, highly active noble metal-free hydrogen evolution catalysts are a priority for all. Herein, we report a facile one-pot hydrothermal synthesis of CoSe2 nanoparticles with their electrocatalytic performance for hydrogen evolution reaction. The synthesized CoSe2 nanoparticles have an average diameter of 50-70 nm with a uniform distribution. They also exhibited good electrocatalytic performance for hydrogen evolution reaction with the onset overpotential and Tafel slope of 140 mV and 95 mV/dec, respectively. The results provide a facile and effective way for the exploration of efficient Co-based HER catalysts.

Facile synthesis of ultrathin Pd–Pt alloy nanowires as highly active and durable catalysts for oxygen reduction reaction

The exploration of efficient nanocatalysts with high activity and stability toward the oxygen reduction reaction (ORR) is extremely important for the advancement of fuel cells but still remains challenging. The capability of rational synthesis of one-dimensional ultrathin Pt-based nanowires could effectively address this issue. Herein, we demonstrate a facile one-pot hydrothermal synthesis of uniform ultrathin Pd–Pt alloy nanowires with a high yield. The judicious adoption of NaI as a structure-directing agent and Pluronic F127 as a stabilizing agent is crucial for the formation of the ultrathin Pd–Pt nanowires by manipulating the reaction kinetics. Due to the bimetallic synergetic effect and unique structural advantage, the as-prepared Pd–Pt alloy ultrathin nanowires outperform commercial Pd black and Pt black catalysts toward ORR, with much improved activity and stability. We expect that this work will provide a promising strategy for the development of efficient ORR electrocatalysts and can also be extendable for the preparation of other one-dimensional bimetallic nanostructures.

One-pot synthesis of graphene-molybdenum oxide hybrids and their application to supercapacitor electrodes

Electrochemical double-layer capacitor (EDLC) electrodes are conventionally based on carbon materials, which provide increased chemical stability and the possibility of a large number of charge and discharge cycles. However, their specific capacitance is generally much lower than pseudo-capacitors based on metal oxide or conductive polymer electrodes. Carbon-based electrodes for electrochemical devices can be hybridized with metal oxide functionalities in order to provide catalytic activity that increases their electrochemical performances. We report the preparation of a conductive hybrid electrode of reduced graphene oxide and molybdenum oxide by a facile one-pot hydrothermal synthesis. A three-dimensional network structure comprising graphene and molybdenum oxide was obtained when phosphomolybdic acid was used as a precursor for molybdenum oxide. The hybrid material contains polycrystalline nanoparticles of molybdenum (IV) oxide (MoO2) that covers the surface of reduced graphene oxide. Compared to graphene electrodes, the hybrid electrodes showed significantly improved specific capacitance, as good as three times higher (381 vs. 140F/g), and considerable reduction of the equivalent series resistance (by about half) when they were used in a supercapacitor with sodium containing aqueous electrolyte.

Facile one-pot hydrothermal synthesis of belt-like β-V6O13 with rectangular cross sections for Li-ion battery application

Belt-like orthorhombic V6O13 (β-V6O13) with rectangular cross sections were successfully synthesized using V2O5, ethanol and H2O as the starting materials by a facile one-pot hydrothermal route. The chemical composition, morphology and electrochemical performances of the sample were briefly discussed. The results show the synthesized β-V6O13 consists of a large quantity of uniform micro- and nano-structures with typical lengths up to several tens of micrometers, widths about several ten nanometers to several hundred nanometers, and thicknesses about several ten nanometers. The electrochemical properties of β-V6O13 showed it exhibited a high initial discharge capacity of 335mAh/g and the capacity retention rate was 73.1% after 75 cycles. The excellent discharge capacities and cycling performance demonstrate the great potential of belt-like β-V6O13 with rectangular cross sections in next-generation high-performance energy storage applications.

One-pot hydrothermal synthesis of Pd/Fe3O4 nanocomposite in HEPES buffer solution and catalytic activity for Suzuki reaction

The Pd/Fe3O4 nanocomposite integrates versatile Pd nanocatalysts with magnetic separation, and has great potential in fine chemical and pharmaceutical synthesis. Its preparation usually involves multi-steps. Herein it was prepared via a facile one-pot hydrothermal synthesis in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution with the assistant of polyvinylpyrrolidone (PVP). HEPES plays multi-functions, particularly as a ligand to enhance the oxidation of Fe2+ to Fe3+ and as a buffer to control the pH value at slightly basic conditions (ca. 7.4) for the formation of crystalline Fe3O4 phase via Fe2+/Fe3+ co-precipitation. PVP works as a dispersant to prevent the particle from aggregation. The obtained Pd/Fe3O4 nanocomposite comprised uniform Pd nanoparticles (ca. 5nm) deposited on Fe3O4 nanocrystals (ca. 15nm). It exhibited excellent catalytic activity and stability for various Suzuki coupling reactions, and could be efficiently recovered with a magnet and recycled for at least 10 cycles without losing catalytic activity.

A facile one-pot hydrothermal synthesis of branched α-MnO2 nanorods for supercapacitor application

Branched α-MnO2 nanorods are synthesized using a facile, green and effective one-pot hydrothermal approach without surfactants or templates. The branched α-MnO2 nanorod electrode exhibited good supercapacitive properties due to its novel textural morphology and crystal structure.

Enhanced optical properties of heterostructured ZnO/CeO2 nanocomposite fabricated by one-pot hydrothermal method: Fluorescence and ultraviolet absorption and visible light transparency

Many researchers investigated the properties of either discrete metal oxide CeO2 or ZnO materials. However, less attention has been paid to the various nanostructure and performances of CeO2 and ZnO nanocomposite up to now. In this paper, a facile and low cost one-pot hydrothermal synthesis method has been adopted to obtained directly precursors of CeCO3OH and Zn5(CO3)2(OH)6 with different Ce atom molar ratios to Zn, which are transformed into their corresponding metal oxide to form the ZnO/CeO2 heterostructure nanocomposites (HSNCs) by pyrolysis. The heterostructure is composed of ZnO and CeO2 monocrystals, simultaneously, CeO2 monocrystals are well dispersed on the surface of ZnO monocrystal for cosmetics. Bing dependent on the analysis results of XRD and TEM for the obtained precursors before and after pyrolysis, the formation mechanism of HSNCs was proposed. To the best of our knowledge, the paper first reported heterostructured ZnO/CeO2 nanocomposite grown in one-pot mixed aqueous solution of cerium nitrate, zinc acetate and urea without other extra surfactant. Additionally, the influence of various Ce/Zn molar ratios on the heterostructure, fluorescence emission and UV–visible absorption properties of HSNCs was investigated in detail. ZnO/CeO2 HSNCs display higher fluorescence emission with the increasing Ce/Zn molar ratio. Meanwhile, the larger Ce/Zn molar ratio of ZnO/CeO2 HSNCs, the stronger transparency in the visible light region and the weaker UV absorption. The results are due to the fact that the band gap of ZnO/CeO2 HSNCs will decrease from 3.25 to 3.08eV when Ce/Zn atom molar ratio is increased from 0 to 0.08. By the comprehensive analysis on the optical performances of HSNCs with the different Ce/Zn atom molar ratios, ZnO/CeO2-0.04 HSNCs could become UV absorber materials and transparent material in the visible region. ZnO/CeO2-0.04 HSNCs with the UV-filtering and Vis-transparent properties is appropriate for personal-care cosmetics.

Facile one-pot hydrothermal synthesis of Pt nanoparticles and their electrocatalytic performance

Pt nanoparticles are synthesized by a facile one-pot hydrothermal synthesis using one kind triblock Pluronic copolymers as reducer and stabilizer for the first time. The size of the Pt nanoparticles can be controlled through simply varying the reaction conditions. The morphology and structure of the Pt nanoparticles were well characterized by different techniques. The electrocatalytic test indicated that the obtained Pt nanoparticles exhibit a better electrocatalytic performance for methanol oxidation in acidic media compared to the commercial Pt/C catalyst. The results of this paper provide a promising approach to prepare Pt-based nanocatalysts for direct alcohols fuel cells (DAFCs).

Facile one-pot hydrothermal synthesis of B/N-codoped TiO2 hollow spheres with enhanced visible-light photocatalytic activity and photoelectrochemical property

B/N-codoped TiO2 hollow spheres (B/N-THs) were synthesized by facile one-pot hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption isotherms, UV–vis diffuse reflectance spectrum (DRS) and X-ray photoelectron spectroscopy (XPS). The B/N-THs have large surface areas (up to 172.1 m2 g−1). The photocatalytic activities of as-prepared THs were evaluated by degradation of Reactive Brilliant Red dye X-3B solution under visible light irradiation. The results showed that B/N-THs exhibited the highest photocatalytic activity due to their high surface area and synergetic effect of B/N-codoped. A photocurrent–time spectrum was examined by anodic photocurrent response to characterize the electron-transferring efficiency in the process of photocatalysis reaction.