One-pot Hydrothermal Strategy Research Articles

Design of long-wavelength emission carbon dots for hypochlorous detection and cellular imaging

A facile strategy for the preparation of nitrogen and phosphorus co-doped carbon dots (N, P-CDs) with long-wavelength emission is attractively proposed in one-pot hydrothermal strategy. The resulting N, P-CDs hold exceptional optical features and display excitation wavelength-independent properties with the emission wavelength at 590 nm, which enable it with the satisfactory relative quantum yield (QY) of 15.6% in long-wavelength region. In addition, the proposed N, P-CDs demonstrates specific selectivity towards ClO− over other competitive reactive oxygen species and exhibits rapid fluorescence response time to ClO−. Moreover, the N, P-CDs exhibits low-cytotoxicity and excellent cell membrane permeability for recognizing ClO− in SMMC-7721 cells, which demonstrates their enormous potential in biological system.

One-pot green hydrothermal synthesis of bio-derived nitrogen-doped carbon sheets embedded with zirconia nanoparticles for electrochemical sensing of methyl parathion

We report a simple, economical and green one-pot hydrothermal strategy to synthesize the bio-derived nitrogen-doped carbon sheets (ONCSs) embedded with zirconia nanoparticles (ZrO2NPs) with orange juice as carbon source and solvent. The ONCSs-ZrO2NPs composite was further applied in the decoration of glassy carbon electrode (GCE) for electrochemical sensing of methyl parathion. The orange juice-derived ONCSs with graphene-like micromorphology showed good electrical conductivity, large specific surface area, and nitrogen functional groups. They could accelerate the electron transport, provide sufficient electrolyte-electrode interface, and improve the surface wettability, thus forming a suitable microenvironment for the redox reaction of MP. The embedded ZrO2NPs in graphene-like ONCSs possessed a strong affinity toward the phosphorus groups on MP molecules, which could promote the preconcentration of MP in the interface of the fabricated sensor and electrolyte. Benefitting from the synergistic effect of ONCSs and ZrO2NPs/GCE, the ONCSs-ZrO2NPs/GCE sensor exhibited excellent peak current response towards MP with a linear detection range of 0.01–15 μg mL−1 and a low detection limit of 0.115 ng mL−1. Furthermore, the ONCSs-ZrO2NPs/GCE sensor presented good capability to investigate the MP levels in romaine and kiwifruit juices with satisfactory recoveries. This work provides a novel and green one-step approach in the development of carbon-based composite materials for high-performance MP electrochemical sensors.

Green and environmental-friendly method to synthesize template free nano grass-flower hierarchical manganese dioxide for high performance supercapacitor

In this article, a simple and environmentally benign one-pot hydrothermal strategy has been developed for the synthesis of nano grass-flower hierarchical manganese dioxide without the use of either templets or acid. Because of synergistic effects of nano grass and nano flower, the nano grass-flower hierarchical structure exhibits specific capacitance of 230 F g−1 at the current density of 1.0 A g−1 and acquires outstanding cycling stability after 10000 cycles with specific capacitance retention of 81%. The samples were analyzed by XRD and FTIR while SEM and TEM were used to confirm the morphology of MnO2. For the evaluation of the electrochemical performance of prepared samples, cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) cycling tests were conducted. Further, an aqueous asymmetrical supercapacitor device (nano grass-flower MnO2//AC and nano grass-MnO2//AC) constructed, nano grass-flower MnO2//AC illustrated an energy density of 30 Wh Kg−1 with a maximum power density of 18000 W kg−1. In addition, the device nano grass-flower MnO2//AC. Finally, this work will provide a new strategy to synthesize worthwhile nanostructures that reveal potential applications in energy storage electrodes.

Antibacterial composite paper with corn stalk-based carbon spheres immobilized AgNPs.

Silver nanoparticles (AgNPs) have been widely used for sterilization due to their broad-spectrum bactericidal properties. However, there exist the problems of premature releasing and accumulative toxicity when free AgNPs are applied. This study proposed a one-pot hydrothermal strategy to synthesize carbon spheres immobilized silver nanoparticles (AgNPs@CS). The synthesis involves with silver ammonia solution as Ag precursor, and corn stalk as green reducing agent and carbon precursor. Furthermore, AgNPs@CS was anchored by cellulose nanofibers (CNF) to obtain the antibacterial composite paper. The obtained CNF/AgNPs@CS paper exhibited superior antibacterial properties against E. coli and S. aureus. Notably, the accumulative release rate of AgNPs from AgNPs@CS was 10.2% in 9days, while that from CNF/AgNPs@CS paper was only 6.7% due to the anchoring effect of both CS and CNF, which was low for avoiding the cumulative toxicity problem. In addition, the mechanical and barrier properties of CNF/AgNPs@CS paper were also improved by 29.4% (tensile index), 2.7% (tear index), 7.4% (burst index), 10% (folding endurance), 0.8% (water vapor transmission) and 9.4% (oxygen transmission rate), respectively. Therefore, the composite paper has potential application as a medical antibacterial material.

Citric acid coated K2GdF7:Ce/Tb nanocrystals for broad and reversible photoluminescence pH sensing

An pH-sensitive citric acid coated Ce/Tb:KGd 2 F 7 nanocrystals with a broad detection range from 3 to 10 is established. Under the 254 nm excitation, the Tb 3+ emission intensity originated from Ce 3+ → Gd 3+ →Tb 3+ decreases gradually with the increase of pH, while its intensity almost keeps unchanged in pH 3 to 6 and increases in pH 6 to 10 under the 311 nm excitation, which activates the ratiometric pH sensing with high sensitivity. An pH-sensitive citric acid coated Ce/Tb:KGd 2 F 7 NCs with a broad detection range from 3 to 10 is established. Under 254 nm excitation, the Tb 3+ emission intensity decreases gradually with the increase of pH, while its intensity almost keeps unchanged below 6 and increased in pH 6 to 10 under 311 nm excitation. • Citric acid coated Ce/Tb:KGd 2 F 7 NCs were prepared via a one-pot hydrothermal strategy. • Under the 254 nm excitation, the PL intensity decreases gradually with the increase of pH. • The intensity almost kept unchanged in pH 3 to 6 and increased in pH 6 to 10 under the 311 nm excitation. • A ratiometric pH sensing route with high sensitivity was obtained.

Hollow flower-like polyhedral α-Fe2O3/Defective MoS2/Ag Z-scheme heterojunctions with enhanced photocatalytic-Fenton performance via surface plasmon resonance and photothermal effects

Hollow Polyhedral superstructures can capture light effectively and have adjustable composite composition, which is useful for constructing Z-scheme systems. Here, rational design of hollow flower-like polyhedral α-Fe2O3/defective MoS2/Ag Z-Scheme heterojunctions is described, using polyhedral α-Fe2O3 as the template and via a one-pot hydrothermal and postdeposition strategy. The hollow flower-like polyhedral heterojunctions utilize multiple reflections of light in the hollow structure to achieve enhanced photocatalytic activity. Defective MoS2 acts as a link between α-Fe2O3 and Ag nanoparticles, providing a great deal of active sites and broadening the photoresponse region. Because of the enhancement of light absorption and surface plasma resonance of Ag, α-Fe2O3/defective MoS2/Ag has significant photothermal effect. The photogenerated carriers can be effectively separated by the construction of a Z-scheme system. Importantly, photocatalytic-Fenton degradation of 2,4-dichlorophenol and salicylic acid over hollow flower-like polyhedral α-Fe2O3/defective MoS2/Ag is higher than that of α-Fe2O3 and α-Fe2O3/defective MoS2.

Hierarchically flower-like WS2 microcrystals for capture and recovery of Au (III), Ag (I) and Pd (II)

In the past few years, two-dimensional (2D) nanomaterials have emerged great potential for the removal of valuable metals and the capture of polluted-heavy metals. Herein, hierarchically flower-like microcrystals with 2D WS2 nanosheets (F-WS2 MCs) were prepared by one-pot hydrothermal synthesis strategy and its adsorption performances for precious metals were systematically assessed. The excellent adsorption efficiencies of ∼86.8%, ∼27.6%, and ∼94.1% towards Ag (I), Pd (II), and Au (III) respectively were achieved within 120 min, and the adsorption curves were in good agreement with a pseudo-second-order kinetic model showing a fast uptake rate at the optimum pH values (1.30 for Au (III), 1.43 for Ag (I), and 3.20 for Pd (II)). The adsorption isotherm followed well in the Langmuir model with the maximum removal capacities (qmax) of 186.2 mg g−1 for Ag (I), 67.29 mg g−1 for Pd (II), and 1340.6 mg g−1 for Au (III), respectively. Furthermore, for recycling purposes, the relevant desorption solution was investigated with different ratios of monobasic acid and thiourea, suggesting the best desorption efficiency of 93.03%, 88.08%, and 85.34% for Ag (I), Pd (II), and Au (III), respectively. By characterizing the crystalline phase, and micromorphology element mapping of F-WS2 MCs before and after adsorption, the strong affinity and significant adsorption–reduction were indicated to dominate the adsorption process. Therefore, this work broadens the application range of WS2 microcrystals, providing an alternative material for capturing precious metals and wastewater treatment applications.

Effect of Cd source on photocatalytic H2 evolution over CdS/MoS2 composites synthesised via a one-pot hydrothermal strategy

As a prototypical non-noble metal photocatalytic composite, CdS/MoS2 has attracted increasing attention for its efficient visible-light H2 evolution. Owing to the simplicity and high reliability, the one-pot hydrothermal strategy has been widely used for CdS/MoS2 synthesis. However, Cd source effect on the hydrothermal synthesis of CdS/MoS2 composites has rarely been investigated. In this study, CdS/MoS2 is synthesised by the one-pot hydrothermal strategy using different Cd sources (CdCl2, Cd(Ac)2, Cd(NO3)2, and CdSO4), and the corresponding visible-light photocatalytic performances of resulting composites are evaluated by hydrogen evolution experiments. The results reveal that Cd source strongly influences the crystallisation, morphology, MoS2 loading, and visible-light absorption of the resulting CdS/MoS2 composites. The CdS/MoS2 composite synthesised using Cd(Ac)2 as precursor exhibited the highest hydrogen evolution rate of 19.34 mmol‧g−1‧h−1, which could be attributed to its larger specific surface area, stronger visible light absorption, and inhibited recombination of photogenerated carriers. In contrast, the use of cadmium nitrate as the Cd source hinders the formation of MoS2 because of the oxidation ability of nitrate groups in the hydrothermal process, which results in its low photocatalytic efficiency. We believe that these findings will provide guidance for the one-pot hydrothermal synthesis of CdS/MoS2 or related composites.

A facile synthesis of magnetic fluorescence Fe3O4-carbon dots for the detection and removal of Hg2+

This article reports a one-pot hydrothermal strategy for preparing fluorescence carbon dots with magnetic properties (Fe3O4-CDs). The Fe3O4-CDs can be utilized for the detection of Hg2+, simultaneously accompanied with a magnetic removal process.

Improved in Situ Synthesis of Heterostructured 2D/2D BiOCl/g-C3N4 with Enhanced Dye Photodegradation under Visible-Light Illumination.

A simple, in situ, and one-pot hydrothermal strategy was applied for the successful manufacturing of heterostructured 2D/2D BiOCl/g-C3N4 photocatalysts, and outstanding photodegradation of Rhodamine B in the condition of visible-light irradiation over the composites emerged. The investigation of various BiOCl/g-C3N4 ratios influencing the activity implied that the optimized B2C1 (mole ratio of BiOCl/g-C3N4 with 2:1) exhibited the higher degradation efficiency than that of the rest of the composites, even higher than that of pure BiOCl and pure g-C3N4, which yielded over 90% in the initial 30 min and reached almost 100% during the whole 70 min irradiation process. Kinds of characterizations demonstrated that the enhancement of photodegradation performance was caused by the intimate contact between BiOCl and g-C3N4 to form the heterostructure, which could benefit the generation of abundant visible-light photoinduced carriers and help enhance their separation and then promote their transportation to the surface.

A novel luminescent dual-ligands europium(III) complex prepared for acetaldehyde sensitive detection

A dual-ligands of terephthalic acid (TPA) and methylimidazole (MIM) co-coordinated Eu(III) complex was designed and constructed based on a simple, low-cost, feasible and effective one-pot hydrothermal strategy. The luminescent inorganic-organic complex integrated the advantages of functional ligands and photoelectric unit of Eu(III), exhibited superior physical-chemical properties. Noteworthily, its fluorescence emission can be selectively and sensitively tuned by acetaldehyde. The reason might be associated with the inner filter effect (IFE) and the influence on complex coordination structure. The complex was further explored as a superior chemosensor for acetaldehyde quantitative detection, and the established sensing detection method exhibited desirable linearity, precision, accuracy, sensitivity, selectivity, and comparable detection limit, which was further employed for acetaldehyde detection from 9 batches of alcoholic beverages and obtained satisfactory results. The novel Eu-complex based analytical method has great application potentials for acetaldehyde sensitive detection from real samples.

Facile design of cubic-like cerium oxide nanoparticles decorated reduced graphene oxide with enhanced microwave absorption properties

Herein, reduced graphene oxide/cerium oxide (RGO/CeO2) hybrid nanocomposites were synthesized by a facile one-pot hydrothermal strategy. Results of morphology observations revealed that the as-prepared hybrid nanocomposites showed improved dispersion of particles with the increasing of contents of RGO and numerously cubic-like CeO2 nanoparticles were uniformly loaded on the crumpled surfaces or edges of thinly flake-like RGO. Moreover, the effects of contents of RGO and concentrations of oxygen vacancies on the microwave absorption properties of RGO/CeO2 hybrid nanocomposites were carefully investigated. It was found that complexing of RGO notably enhanced the microwave absorption properties of CeO2 nanoparticles, and the microwave absorption properties of as-prepared hybrid nanocomposites could be optimized by facilely modulating the contents of RGO. Remarkably, the obtained hybrid nanocomposites with the content of RGO of 4.1 wt% exhibited the best microwave absorption performance, i.e. the minimum reflection loss reached −49.2 dB at 5.2 GHz with a matching thickness of 4.46 mm, and effective absorption bandwidth achieved 4.1 GHz (13.4–17.5 GHz) with a thin thickness of merely 1.7 mm. Besides, the underlying microwave absorption mechanisms of as-prepared hybrid nanocomposites were proposed. It was believed that our results could shed light on the design and fabrication of graphene-based hybrid composites as high-efficient microwave absorbers.

Iridium doped ZnO nanocomposites: Synergistic effect induced photocatalytic degradation of methylene blue and crystal violet

A series of novel iridium (Ir) nanoparticles doped ZnO nanocomposites were constructed via one-pot simple hydrothermal strategy and used as a visible light driven photocatalyst for the degradation of Methylene Blue (MB) and Crystal Violet (CV). The synthesized pure ZnO and Ir loaded ZnO nanocomposites were systematically characterized by crystal structure, structural morphology, elemental and optical properties. The photocatalytic performance of Ir doped ZnO (2%) nanocomposite is much higher than that of pure ZnO and other Ir doped ZnO nanocomposites and more encouragingly, 10 mg/L of MB can be completely removed within 50 min of irradiation. The Ir doped in the lattice of ZnO can act as the electron trapping sites, which effectively improve the charge carrier separation. The enhanced photocatalytic activity of Ir doped ZnO (2%) composite is mainly attributed to the synergistic interaction between ZnO and Ir NPs, which could not only enhance the light absorption range, but also accelerate photo-induced interfacial charge transfer during the photocatalytic processes. Influence factors such as initial dye concentrations and catalyst doses were investigated. The generation of reactive oxidative species (ROS) such as OH, h+ and O2− was also been demonstrated. Moreover, this study also paves a new vista for promising applications in environmental water purity and energy harvesting.

Enhanced the photoelectrocatalytic performance of TiO2 nanotube arrays by the synergistic sensitization of Ag-AgBr nanospheres.

Ag-AgBr nanospheres were synthesized on the tubular surface of TiO2 nanotube arrays (TiO2 NTA/Ag-AgBr) by the one-pot hydrothermal deposition strategy using cetyltrimethyl ammonium bromide (CTAB) as bromine source and morphology controlling agent. The results showed that the TiO2 NTA/Ag-AgBr (0.025) prepared with 0.025 g CTAB had the uniform particle distribution, high visible light absorption, photoelectric conversion activity and photoelectrocatalytic (PEC) removal of organic dyes and heavy metal ions. The high photocatalytic decomposition of organic pollutants in waste water was attributed to the synergistic effect of Ag-AgBr nanospheres with the strong visible light response and effective separation of electron-hole pairs. The active group and photocatalytic mechanism for the rapid pollutant removal were systematically explored. This work will open the window of TiO2 NTA based photoelectrodes for the applications in solar energy conversion and dyeing waste water purification.

Wavy SnO2 catalyzed simultaneous reinforcement of carbon dioxide adsorption and activation towards electrochemical conversion of CO2 to HCOOH

The tin oxide (SnO2) based materials have emerged as one of the most promising candidates to highly electrolyze the carbon dioxide (CO2) and produce formic acid. However, it still cannot meet the requirement for practical application because a substantial overpotential is needed to achieve a high HCOOH Faraday efficiency (FE) along with a large current density. In this work, we report the preparation of an “all in one” wavy SnO2 having abundant oxygen vacancies, grain boundaries and low-coordinated active sites (such as edge and corner sites) by a facile yet simple one-pot hydrothermal strategy, which simultaneously intensifies the adsorption and activation of CO2, facilitates electron transfer and thus, improves the efficiency of CO2 reduction reaction (CO2RR). Importantly, this study demonstrates a wavy SnO2 (NW-SnO2) with optimized surface structure for the significantly enhanced electrocatalytic reduction of CO2 to HCOOH with maximum FEHCOOH = 87.4% and EEHCOOH = 57.5% at −1.0 vs VRHE. The synthesizing process reported herein is superior to a number of the current SnO2 based electrocatalysts since it is much easier, more cost effective and benign, an apparent advantage in terms of its future large scale of applications. This study could be extended to much abroad applications and serves as a guide to synthesize other metallic oxide based catalysts for CO2RR by tuning surface structure.

Facile design of nitrogen-doped reduced graphene oxide/zinc ferrite hybrid nanocomposites with excellent microwave absorption in the X-band

Abstract Herein, nitrogen-doped reduced graphene oxide/zinc ferrite (NRGO/ZnFe2O4) hybrid nanocomposites were synthesized through a facile one-pot hydrothermal strategy by using graphene oxide (GO) as a substrate. Results demonstrated that the additive amounts of GO had remarkable influence on the micromorphology and microwave absorption properties of NRGO/ZnFe2O4 hybrid nanocomposites. The as-prepared hybrid nanocomposites showed good dispersion of nanoparticles as the additive amounts of GO increasing and numerous ZnFe2O4 nanoparticles uniformly loaded on the crumpled surface of thinly flake-like NRGO were observed. It was found that the obtained hybrid nanocomposites exhibited obviously enhanced microwave absorption performance than that of pure ZnFe2O4. Remarkably, the minimum reflection loss reached −54.6 dB at 10.0 GHz (X-band) and effective absorption bandwidth achieved 4.2 GHz (11.8–16.0 GHz) with a thickness of merely 2.0 mm and filler loading of 40 wt%. It was believed that our results could be helpful for designing and fabricating graphene-based composites as high-efficient microwave absorbers.

A facile synthesis of self-doped carbon dots from 2-aminoterephthalic acid and their applications

Self-doped carbon dots with N elements (N-CDs) are successfully prepared through one-pot hydrothermal carbonization strategy by using 2-aminoterephthalic acid as a new precursor. The as-prepared N-CDs show a size of 5–10 nm and display wavelength-independent fluorescence. Their maximum excitation and emission wavelength are 340 and 423 nm, respectively. They demonstrate a highly selective and sensitive detection of Fe3+ ions in the range of 5–100 μM via an effective fluorescence quenching mechanism. Furthermore, the cotton fabrics treated by these N-CDs have excellent ultraviolet (UV)-protective property. Therefore, they have potential to be used for the detection of Fe3+ ions, the UV fluorescent ink and the UV protection for cotton fabrics.

Nitrogen, Cobalt Co-doped Fluorescent Magnetic Carbon Dots as Ratiometric Fluorescent Probes for Cholesterol and Uric Acid in Human Blood Serum.

Detection of cholesterol and uric acid biomarkers is of great importance for clinical diagnosis of several serious diseases correlated with their variations in human blood serum. In this study, a new kind of well selective and highly sensitive ratiometric fluorescent probe for cholesterol and uric acid determination in human blood serum was innovatively developed on the basis of the inner filter effect (IFE) process of nitrogen, cobalt co-doped carbon dots (N,Co-CDs) with 2,3-diaminophenazine (DAP). DAP was the oxidative product during the oxidation reaction between o-phenylenediamine and H2O2. Fluorescent magnetic N,Co-CDs possessing blue emission and magnetic property were prepared through a facile one-pot hydrothermal strategy by using citric acid, diethylenetriamine, and cobalt(II) chloride hexahydrate as precursors. N,Co-CDs exhibited good ferromagnetic property and excellent optical properties even in extremely harsh environmental conditions, implying the huge potential applications of such N,Co-CDs in biological areas. On the basis of the IFE process between N,Co-CDs and DAP, N,Co-CDs were applied to establish ratiometric fluorescent probes for the indirect detection of cholesterol and uric acid that participated in enzyme-catalyzed H2O2-generation reactions. The established IFE-based fluorescent probes exhibited relatively low detection limits of 3.6 nM for cholesterol and 3.4 nM for uric acid, respectively. The fluorescent probe was successfully utilized for the determination of cholesterol and uric acid in human blood serum with satisfying results, which provided an informed perspective on the applications of such doped CDs to explore the specific and sensitive nanoprobe in disease diagnoses and clinical therapy.

Design and electromagnetic wave absorption properties of reduced graphene oxide/multi-walled carbon nanotubes/nickel ferrite ternary nanocomposites

Herein, amphiphilic graphene oxide (GO) was used as the “surfactant” to directly disperse pristine multi-walled carbon nanotubes (MWCNTs) in aqueous dispersions and the reduced graphene oxide/multi-walled carbon nanotubes/nickel ferrite (RGO/MWCNTs/NiFe2O4) ternary nanocomposites were further synthesized by a facile one-pot hydrothermal strategy. The structure, compositions, micromorphology and electromagnetic parameters of the ternary nanocomposites were investigated by various analytical techniques. Experimental results revealed that the ternary nanocomposites exhibited the enhanced electromagnetic wave (EMW) absorption performance compared with the binary nanocomposite and single NiFe2O4. The minimum reflection loss (RLmin) reached −50.2 dB with a thin thickness of 1.4 mm and effective absorption bandwidth (EAB, RL ≤ −10 dB) was 5.0 GHz (13–18 GHz). Meanwhile, the EAB could reach 14.64 GHz (91.5% of 2–18 GHz) by facilely adjusting the coating thicknesses from 1 to 5 mm. Furthermore, the possible EMW absorption mechanism was proposed. Besides, the EMW absorption performance was highly tunable by changing the additive amounts of MWCNTs, filler loading ratios and coating thicknesses. Our results could be helpful for designing and developing novel graphene-based high-performance EMW absorbers.

Facile synthesis of PdFe alloy tetrahedrons for boosting electrocatalytic properties towards formic acid oxidation.

The controllable synthesis of multi-metal nanocrystals with a tetrahedral shape is significant for constructing high-efficiency electrocatalysts. However, due to the great distinction among the thermodynamic reduction potentials of different metal precursors, it is difficult to achieve tetrahedron-shaped alloy nanocrystals with a uniform {111} crystal surface and low surface energy. Herein, we reported a one-pot hydrothermal synthetic strategy to achieve high-yield PdFe alloy tetrahedrons. The unique structure endowed an impressive surface area-to-volume ratio, well distribution of Pd and Fe sites, and essential electronic effects, due to which they could be employed as formic acid oxidation reaction (FAOR) catalysts. As expected, the PdFe alloy tetrahedrons exhibited 4.8 and 2.4 times higher mass activity (595.8 A g-1) and specific activity (33.4 A m-2) compared to commercial Pd black, respectively; they also showed enhanced electrocatalytic stability and good resistance to CO poisoning. This work demonstrates the potential applications of bimetal Pd-based tetrahedrons as promising anode catalysts in a direct formic acid fuel cell.