还原氧化石墨烯-硒化银纳米复合材料的水热合成与表征及其活性氧物种产生(英文)

A visible-light photocatalyst containing Ag2Se and reduced graphene oxide(RGO) was synthesized by a facile sonochemical-assisted hydrothermal method. X-ray diffraction, scanning electron mi-croscopy with energy-dispersive X-ray analysis, and ultraviolet-visible diffuse reflectance spectros-copy results indicated that the RGO-Ag2Se nanocomposite contained small crystalline Ag2Se nano-particles dispersed over graphene nanosheets and absorbed visible light. The high crystallinity of the nanoparticles increased photocatalytic activity by facilitating charge transport. N2 adsorp-tion-desorption measurements revealed that the RGO-Ag2Se nanocomposite contained numerous pores with an average diameter of 9 nm, which should allow reactant molecules to readily access the Ag2Se nanoparticles. The RGO-Ag2Se nanocomposite exhibited higher photocatalytic activity than bulk Ag2Se nanoparticles to degrade organic pollutant rhodamine B and industrial dye Texbrite BA-L under visible-light irradiation(λ 420 nm). The generation of reactive oxygen spe-cies in RGO-Ag2Se was evaluated through its ability to oxidize 1,5-diphenylcarbazide to 1,5-diphenylcarbazone. The small size of the Ag2Se nanoparticles in RGO-Ag2Se was related to the use of ultrasonication during their formation, revealing that this approach is attractive to form po-rous RGO-Ag2Se materials with high photocatalytic activity under visible light.     

One-step hydrothermal synthesis of nitrogen doped reduced graphene oxide-silver nanocomposites: Catalytic performance

The aim of this study is to efficiently utilize catalytic properties of silver nanoparticles and nitrogen doped graphene and their combined synergistic effect. For this purpose, nitrogen doped reduced graphene oxide-silver (NrGO-Ag) nanocomposites were synthesized by a facile, environmentally friendly, one-pot hydrothermal method for the first time and characterized by UV–Vis, FTIR, XRD, XPS, SEM, and TEM. Catalytic activity of the synthesized nanocomposites was tested against 4-nitrophenol (4-NP) and methylene blue (MB) reduction reactions in the presence of NaBH₄. Total degradation was achieved in both reactions in 210 and 44 s, and pseudo first order reaction rate constants were calculated as 0.0071 and 0.0322 s⁻¹ for 4-NP and MB reduction reactions, respectively.     

Rhodamine B degradation and reactive oxygen species generation by a ZnSe-graphene/TiO2 sonocatalyst

Nanostructured ZnSe-graphene/TiO2 was synthesized by a hydrothermal-assisted approach. ZnSe-graphene/TiO2 exhibited favorable adsorption of rhodamine B, a wide wavelength absorption range, and efficien...     

Biosynthesis and characterization of lead selenide semiconductor nanoparticles (PbSe NPs) and its antioxidant and photocatalytic activity

The current study fabricated novel lead selenide nanoparticles (PbSe NPs) by a simple biological benign process with Trichoderma sp. WL-Go. Ultraviolet–visible spectroscopy (UV–vis), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transfer infra-red (FTIR) spectroscopic analysis, Raman spectroscopy and Photoluminescence (PL) were used to characterize the physicochemical properties of the fabricated NPs. Synthesis at pH 8 with 0.5 g biomass of strain WL-Go and (1:1) mM of SeO₂: Pb(NO₃)₂ were the optimal synthesis conditions to achieving 10–30 nm cubic faced centered NPs. The PbSe NPs served as catalyst for investigating the antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and photodegradation ability of rhodamine B dye (10 mg/L). The results indicated that the NPs could eliminate up to 88.60% of free radicals after adding 600 g/mL NPs and could photodegrade 82% of rhodamine B in 30 min. Thus, this study provides new knowledge and strategies for the future use of an environmentally benign bio- catalytic PbSe NPs to efficiently eliminate free radicals and in treatment of persistent organic pollutants in wastewaters.     

Surfactant assisted hydrothermal synthesis of SnO nanoparticles with enhanced photocatalytic activity

SnO nanoparticles have been successfully synthesized in the presence of Triton-X 100 (TX-100) surfactant via hydrothermal method for the first time, and the photocatalytic activity under UV and visible light irradiation for the degradation of Methylene Blue (MB) and Rhodamine B (RdB) organic textile dyes was investigated. The structural, morphological and chemical characterizations were investigated by using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), UV–vis. diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) analysis. The results reveal that the addition of surfactant, TX-100, in the precursor solutions leads to reduction in crystallite size with significant changes in morphological structure of SnO nanoparticles. The synthesized SnO nanoparticles show excellent photocatalytic activity under UV or visible light irradiation. MB and RdB dyes degraded completely under UV irradiation after 90 and 150 min, respectively. Also, MB and RdB dyes degraded only 150 min later under visible light illumination with a little amount of photocatalyst (0.8 g/L). Hence, this work explores the facile route to synthesizing efficient SnO nanoparticles for degrading organic compound under both UV and visible light irradiations.     

Facile preparation of hydrogenated graphene by hydrothermal methods and the investigation of its ferromagnetism

In this paper, a hydrothermal approach is utilized for the first time in integrating graphene oxide (GO), acetic acid (HAc) and nickel foam to prepare hydrogenated graphene (HG). There are two primary aims of this study: one is to ascertain the structure of the as-prepared HG, and the other one is to investigate the ferromagnetism of the HG. Under hydrothermal conditions, GO was reduced and hydrogenated by HAc, while the nickel foam served as a catalyst. This work provides a novel and facile route for the synthesis of hydrogenated graphene, which may lead to the application of hydrogenated graphene in spin electronic devices.     

Photocatalytic properties of Zinc selenide doped with cobalt oxide nanocomposite

In this work, ZnSe/Co₃O₄ was synthesized by hydrothermal method. The samples were characterized by XRD, SEM, TEM, EDS, XPS, BET, UV–vis techniques. The activity of the composite photocatalytic materials was detected by visible light catalytic degradation of methylene blue (MB). The catalytic effect was the most obvious when the composite ratio was 1:10, with the removal rate reaching to 93.6% of 10 ?mg/L MB within 120 ?min of visible light irradiation. After further analysis of the catalyst, ZnSe/Co₃O₄ has a broader application prospect due to its high efficiency and low price.     

Ag2S-石墨烯/TiO2的声化学法合成及可见光催化活性（英文）

Ag2S‐graphene/TiO2 composites were synthesized by a facile sonochemical method.The products were characterized by X‐ray diffraction,scanning electron microscopy,energy dispersive X‐ray spectroscopy,transmission electron microscopy,and UV‐Vis diffuse reflectance spectrophotometry.During the synthesis reaction,the reduction of graphene oxide and loading of Ag2S and TiO2 particles were achieved.The Ag2S‐graphene/TiO2 composites possessed a large adsorption capacity for dyes,an extended light absorption range,and efficient charge separation properties.Hence,in the photodegradation of rhodamine B,a significant enhancement in the reaction rate was observed with the Ag2S‐graphene/TiO2 composites as compared to pure TiO2.The generation of reactive oxygen species was detected by the oxidation of 1,5‐diphenyl carbazide to 1,5‐diphenyl carbazone.The high activity was attributed to the synergetic effects of high charge mobility and the red shift in the absorption edge of the Ag2S‐graphene/TiO2 composites.     

Rational hydrothermal synthesis of graphene quantum dots with optimized luminescent properties for sensing applications

Hydrothermal synthesis using graphene oxide (GO) as a precursor has been used to produce luminescent graphene quantum dots (GQDs). However, such a method usually requires many reagents and multistep pretreatments, while can give rise to GQDs with low quantum yield (QY). Here, we investigated the concentration, the temperature of synthesis, and the pH of the GO solution used in the hydrothermal method through factorial design experiments aiming to optimize the QY of GQDs to reach a better control of their luminescent properties. The best synthesis condition (2 mg/mL, 175 °C, and pH = 8.0) yielded GQDs with a relatively high QY (8.9%) without the need of using laborious steps or dopants. GQDs synthesized under different conditions were characterized to understand the role of each synthesis parameter in the materials' structure and luminescence properties. It was found that the control of the synthesis parameters enables the tailoring of the amount of specific oxygen functionalities onto the surface of the GQDs. By changing the synthesis' conditions, it was possible to prioritize the production of GQDs with more hydroxyl or carboxyl groups, which influence their luminescent properties. The as-developed GQDs with tailored composition were used as luminescent probes to detect Fe³⁺. The lowest limit of detection (0.136 μM) was achieved using GQDs with higher amounts of carboxylic groups, while wider linear range was obtained by GQDs with superior QY. Thus, our findings contribute to rationally produce GQDs with tailored properties for varied applications by simply adjusting the synthesis conditions and suggest a pathway to understand the mechanism of detection of GQDs-based optical sensors.     

Hydrothermal synthesis of reduced graphene sheets/Fe2O3 nanorods composites and their enhanced electrochemical performance for supercapacitors

Reduced graphene nanosheets/Fe₂O₃ nanorods (GNS/Fe₂O₃) composite has been fabricated by a hydrothermal route for supercapacitor electrode materials. The obtained GNS/Fe₂O₃ composite formed a uniform structure with the Fe₂O₃ nanorods grew on the graphene surface and/or filled between the graphene sheets. The electrochemical performances of the GNS/Fe₂O₃ hybrid supercapacitor were tested by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge tests in 6 M KOH electrolyte. Comparing with the pure Fe₂O₃ electrode, GNS/Fe₂O₃ composite electrode exhibits an enhanced specific capacitance of 320 F g⁻¹ at 10 mA cm⁻² and an excellent cycle-ability with capacity retention of about 97% after 500 cycles. The simple and cost-effective preparation technique of this composite with good capacitive behavior encourages its potential commercial application.     

Functionalized reduced graphene oxide/epoxy composites with enhanced mechanical properties and thermal stability

One-pot hydrothermal reduction of graphene oxide (GO) in N-methyl-2-pyrrolidone (NMP) suspension was performed, wherein GO surface were functionalized by free radicals generated from NMP molecules. The NMP functionalized reduced GO (NMPG) nanosheets were then incorporated into epoxy matrix to prepare epoxy composites. The significant improvement of 100 and 240% in fracture toughness (critical intensity factor, K_IC) and fracture energy (critical strain energy release rate, G_IC) achieved from single edge notched bending (SENB) test revealed the excellent toughening ability of NMPG. The improved compatibility and interfacial interaction between the epoxy matrix and NMPG yielded∼28, 19 and 51% improvement in tensile strength, Young's and storage modulus, respectively. Thermal stability of pure epoxy and its composites was determined at 5, 10 and 50% weight loss, which showed 30, 27.5 and 29 °C improvement with 0.2 wt% NMPG loading. The work provides a simple method to prepare graphene-based epoxy composites with improved performance.     

Preparation and characterization of a novel zeolite using hydrothermal synthesis in a stirred reactor

This paper describes the preparation of novel zeolite particles by the hydrothermal method in a stirred reactor. The variations between certain properties of the resulting zeolites, such as morphology by the scanning electron microscopy (SEM), pore properties (i.e., surface areas, pore volume, and porosity) by the surface area & porosity analyzer, crystallinity by the X-ray diffraction (XRD) and Si/Al ratio by the inductively coupled plasma-atomic absorption spectrometer (ICP-AES), and the process parameters, such as aging time, agitation speed, temperature and pressure, were studied at a specific gel composition. The optimal value of the Brunauer–Emmett–Teller (BET) surface area was found to be over 400 m²/g in the resulting microporous zeolite, indicating that the size was centered on about 0.5 nm. The XRD image was indicative of the probable formation of zeolite-P2 in the hydrothermal synthesis.     

Green synthesis and characterization of Ag and Ag/Fe3O4 nanocomposites for antimicrobial effect and rhodamine- B dye degradation

We used a simple two-stage tactic to design and synthesize a magnetically separable catalyst (MSC) Ag/Fe₃O₄ by combining independently synthesized Fe₃O₄ and Jatropha curcas root functionalized Ag nanoparticles (NPs) at room temperature. The phase composition of Ag/Fe₃O₄ NCs was revealed by morphological and structural assessment. The derived Ag/Fe₃O₄ nanocomposites demonstrated outstanding antimicrobial activity against Gram-negative Pseudomonas aeruginosa comparing to Gram-positive Bacillus subtilis which was determined by the agar well diffusion method. This is due to positively charged surface of metal oxide NPs that may bind to cell membrane. Interestingly, Ag–Fe₃O₄ NCs demonstrated good photocatalytic activity for organic dye degradation. According to a kinetic study, Ag/Fe₃O₄ MSC removed 99% of Rhodamine B at a rate constant of 1.89 min^?1. The photoelectron could perhaps ultimately collide only with dissolved solids in the substrate to form superoxides, which can damage the dye. Notably, the MSCs reusability was tested using magnetic detachment without sacrificing photocatalytic efficiency. This finding represents a significant breakthrough in the domain of wastewater treatment and biomedicine.     

Preparation and characterization of functionalized graphene oxide/carbon fiber/epoxy nanocomposites

Graphene oxide (GO) was functionalized using three different diamines, namely ethylenediamine (EDA), 4,4′-diaminodiphenyl sulfone (DDS) and p-phenylenediamine (PPD) to reinforce an epoxy adhesive, with the aim of improving the bonding strength of carbon fiber/epoxy composite. The chemical structure of the functionalized GO (FGO) nanosheets was characterized by elemental analysis, FT-IR and XRD. Hand lay-up, as a simple method, was applied for 3-ply composite fabrication. In the sample preparation, the fiber-to-resin ratio of 40:60 (w:w) and fiber orientations of 0°, 90°, and 0° were used. The GO and FGO nanoparticles were first dispersed in the epoxy resin, and then the GO and FGO reinforced epoxy (GO- or FGO-epoxy) were directly introduced into the carbon fiber layers to improve the mechanical properties. The GO and FGO contents varied in the range of 0.1–0.5 wt%. Results showed that the mechanical properties, in terms of tensile and flexural properties, were mainly dependent on the type of GO functionalization followed by the percentage of modified GO. As a result, both the tensile and flexural strengths are effectively enhanced by the FGOs addition. The tensile and flexural moduli are also increased by the FGO filling in the epoxy resin due to the excellent elastic modulus of FGO. The optimal FGO content for effectively improving the overall composite mechanical performance was found to be 0.3 wt%. Scanning electron microscopy (SEM) revealed that the failure mechanism of carbon fibers pulled out from the epoxy matrix contributed to the enhancement of the mechanical performance of the epoxy. These results show that diamine FGOs can strengthen the interfacial bonding between the carbon fibers and the epoxy adhesive.     

Preparation and characterization novel dioctyl terephthalate blended polyvinyl alcohol-composite films incorporated with the graphene oxide and silver nanoparticles

Dioctyl terephthalate is of great interest as a replacement for the phthalate plasticizers such as dioctyl phthalate and diisononyl phthalate due to its orthophthalate-free and non-carcinogenic properties. This study focused on the production, characterization and optimization of the quality characteristics of its film properties, such as the mechanical, hydrophilic and thermal properties of dioctyl terephthalate-blended polyvinyl alcohol composites modified with graphene oxide and silver nanoparticles using TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) based Taguchi Method. Dioctyl terephthalate has brought remarkable features, such as high elastic modulus, and hydrophilic and thermal stability to the polyvinyl alcohol matrix. The optimum Dioctyl terephthalate -blended polyvinyl alcohol films have a 2.26 times lower contact angle and a 13.41 times higher elastic modulus than the reference polyvinyl alcohol film. Dioctyl terephthalate should be preferentially used to manufacture more durable and hydrophilic composite films such as fibers, disposable underpad or industrial swab, instead of toxic phthalate plasticizers.     

A one-flask synthesis and characterization of novel symmetrical pyridyl monoselenides and X-ray crystal structure of bis(5-bromo-2-pyridyl) selenide and bis(2-bromo-5-pyridyl) selenide

The present work reports an efficient one-pot synthesis of symmetrical pyridyl monoselenides by the reaction of bromo-/iodopyridines with the isopropylmagnesium chloride, ⁱPrMgCl followed by quenching with selenyl chloride, SeCl₂. The current methodology constitutes a convenient synthesis of bis(5-bromo-2-pyridyl) selenide (I), bis(2-bromo-5-pyridyl) selenide (II) and bis(2,5-dibromo-3-pyridyl) selenide (III) under cryogenic conditions requiring shorter time duration to give satisfactory yields. The hitherto unknown compounds have been characterized by elemental analysis and various spectroscopic techniques i.e., ¹H NMR, ¹³C NMR, FT-IR, mass spectrometry and X-ray crystallography.     

One-step facile synthesis of poly(N-vinylcarbazole)-polypyrrole/graphene oxide nanocomposites: enhanced solubility,thermal stability and good electrical conductivity

Poly (N-vinylcarbazole)-polypyrrole/graphene oxide (PNVC-Ppy/GO) nanocomposites have been successfully prepared by one-step chemical oxidative polymerization using ferric chloride hexahydrate in the presence of dodecyl benzene sulfonic acid. The composite formation, morphology and the crystallinity of the composite have been characterized by FTIR spectroscopy, FESEM, and XRD, respectively. The incorporation of graphene oxide into the PNVC-Ppy matrix induces interaction between graphene oxide and PNVC-Ppy via hydrogen bonding and π–π* stacking. This π–π* stacking between the GO layers and PNVC-Ppy produces longer conjugation length leading to a higher solubility in organic solvents and enhanced electron mobility. The information of conjugation chain length and charge transfer capacity at the interface of the composite has been obtained from the Raman spectroscopy and photolumincience spectroscopy. The improved thermal stability and electrical d.c. conductivity (0.123?S/cm) of the resulting PNVC-Ppy/GO composite compared to the PNVC–Ppy copolymer (0.08?S/cm) is attributed to the incorporation of graphene oxide in the composite.     

Facile synthesis of cobalt oxide/reduced graphene oxide composites for electrochemical capacitor and sensor applications

Reduced graphene oxide sheets decorated with cobalt oxide nanoparticles (Co₃O₄/rGO) were produced using a hydrothermal method without surfactants. Both the reduction of GO and the formation of Co₃O₄ nanoparticles occurred simultaneously under this condition. At the same current density of 0.5 A g⁻¹, the Co₃O₄/rGO nanocomposites exhibited much a higher specific capacitance (545 F g⁻¹) than that of bare Co₃O₄ (100 F g⁻¹). On the other hand, for the detection of H₂O₂, the peak current of Co₃O₄/rGO was 4 times higher than that of Co₃O₄. Moreover, the resulting composite displayed a low detection limit of 0.62 μM and a high sensitivity of 28,500 μA mM⁻¹cm⁻² for the H₂O₂ sensor. These results suggest that the Co₃O₄/rGO nanocomposite is a promising material for both supercapacitor and non-enzymatic H₂O₂ sensor applications.     

Construction of zinc selenide microspheres decorated with octadecylamine-functionalized reduced graphene oxide as an effective catalyst for the dual-mode detection of chloroquine phosphate

Zinc selenide microspheres were constructed using a simple hydrothermal technique at 180°C. It was ultrasonically treated with reduced graphene oxide modified with octadecylamine alkyl amine to form a hybrid nanocomposite. The optical, structural, and functional analysis by ultraviolet (UV) absorbance, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy revealed the crystal nature of the microspheres and the successful formation of the nanocomposite. Field emission scanning electron microscopy and transmission electron microscopy were done to study the morphological properties of the material. It was further used to fabricate a dual-modality sensor using both electrochemical and absorbance techniques for the detection of antimalarial drug chloroquine phosphate (CQP), which was used for the treatment of COVID-19 (SARS-CoV-2) virus. For electrochemical detection, the sensor showed a very low detection limit of 1.43 nM at a linear working range of 0.199–250.06 μM and a high sensitivity of 43.912 μA/μM/cm². For UV-based detection, the sensor showed a very low detection limit of 6.88 nM at a linear working range of 0.045–7.324 μM. The sensor showed excellent analyte recovery rate for real-time analysis in biological as well as environmental samples. The results suggested that the sensor is effective for the detection of CQP with feasibility for future commercialization.     

Sonochemical synthesis and characterization of Cu2HgI4 nanostructures photocatalyst with enhanced visible light photocatalytic ability

These days, an important concern in water contamination is the remaining dyes from various sources (for instance, dye and dye intermediates industries, pulp and paper industries, textile industries, craft bleaching industries, tannery, and pharmaceutical industries, etc.), and a broad range of persistent organic contamination has been entered to the wastewater treatment systems or natural water supplies. Indeed, it is extremely hazardous and toxic to the living organism. Therefore, it is necessary to remove these organic pollutants before releasing them into the environment. Photocatalysis is a quickly growing technology for sewage procedures. For this purpose, Cu₂HgI₄ nanostructures were prepared via facile, and cost-effective sonochemical method. The effect of varied circumstances, such as various surfactants, sonication power, and sonication time was considered on the crystallinity, structure, shape, and particle size of products. Cu₂HgI₄ possesses a suitable bandgap (2.2 eV) in the visible area. The photocatalytic performance of the Cu₂HgI₄ was surveyed for the elimination of various organic dyes under visible radiation and exposed that this compound could degrade and remove methyl orange about 94.2% in an acidic medium after 160 min under visible light. Besides, the result showed that various parameters, including, pH, dye concentration, types of dyes, catalyst dosages, and time of irradiation affected the photocatalytic efficiency.