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1.
《中国化学》2017,35(9):1405-1410
Pd and Pdx Ni nanoparticles have been supported on reduced graphene oxide (Pd/rGO and Pdx Ni/rGO ) by using the microwave‐assisted heating method in glycol. The morphology, composition and electrochemical performance have been characterized by TEM , XRD , XPS and electrochemical methods. The XRD and XPS results show that there are no PdNi alloy particles formed in Pdx Ni/rGO and the composites exist mostly in the form of Pd0 and NiOOH species. The electrochemical results reveal that Pdx Ni/rGO synthesized from the feeding source of Pd and Ni with an atomic ratio of 4∶1 exhibits higher activity, better stability and smaller electron transfer resistance toward formic acid electro‐oxidation compared with commercial Pd/C, Pd/rGO and other Pdx Ni/rGO samples. The excellent electrocatalytic performance indicates that the addition of appropriate amount of Ni can greatly enhance the activity and stability of Pd catalysts for formic acid oxidation.  相似文献   

2.
In this work, the reduced graphene oxide functionalized with poly dimethyl diallyl ammonium chloride (PDDA) modified palladium nanoparticles (PDDA‐rGO/Pd) had been facile synthesized and used as the sensing layer for sensitive determination of capsaicin. The prepared composite was characterized by transmission electron microscopy, UV‐visible absorption spectroscopy. The image demonstrated that Pd nanoparticles were uniformly distributed on the graphene surface. The electrochemical properties of the prepared sensor were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the nanocomposite exhibits attractive electrocatalytic activity towards the oxidation of capsaicin. This attributed to the synergistic action of the excellent properties of Pd nanoparticles and graphene nanosheets. Under optimized conditions, the electrochemical sensor possessed a dynamic linear range from 0.32 μM to 64 μM with a detection limit of 0.10 μM (S/N=3) for capsaicin detection. Moreover, the cost‐effective and simple fabrication procedure, good reproducibility and stability as well as acceptable accuracy for capsaicin determination in actual samples are also the main advantages of this method, which might have broad application in other amide alkaloid detection.  相似文献   

3.
Well distributed Pd‐Cu bimetallic alloy nanoparticles supported on amine‐terminated ionic liquid functional three‐dimensional graphene (3D IL‐rGO/Pd‐Cu) as an efficient catalyst for Suzuki cross‐coupling reaction has been prepared via a facile synthetic method. The introduction of IL‐NH2 cations on the surface of graphene sheets can effectively avoid the re‐deposition of graphene sheets, allowing the catalyst to be reused up to 10 cycles. The addition of Cu not only saves cost but also ensures high catalytic efficiency. It is worthy to note that the catalyst 3D IL‐rGO/Pd2.5Cu2.5 can efficiently catalyze the Suzuki cross‐coupling reaction with the yield up to 100% in 0.25 h, almost one‐fold higher than that by the pristine IL‐rGO/Pd2.5 catalyst (52%). The Powder X‐Ray Diffraction (XRD), combining energy dispersive X‐ray spectroscopy (EDS) mapping results confirm the existence and distribution of Pd and Cu in the bimetallic nanoparticles. The transmission electron microscopy (TEM) reveals the nanoparticle size with an average diameter of 3.0 ± 0.5 nm. X‐ray photoelectron spectroscopy (XPS) analysis proved the presence of electron transfer from Cu to Pd upon alloying. Such alloying‐induced electronic modification of Pd‐Cu alloy and 3D ionic liquid functional graphene with large specific surface area both accounted for the catalytic enhancement.  相似文献   

4.
《Electroanalysis》2017,29(11):2591-2601
In present work, reduced graphene oxide nanosheets (rGO) decorated with trimetallic three‐dimensional (3D) Pt−Pd−Co porous nanostructures was fabricated on glassy carbon electrode (Pt−Pd−Co/rGO/GCE). First, GO suspension was drop‐casted on the electrode surface, then GO film reduction was carried out by cycling the potential in negative direction to form the rGO film modified GCE (rGO/GCE). Then, electrodeposition of the cobalt nanoparticles (CoNPs) as sacrificial seeds was performed onto the rGO/GCE by using cyclic voltammetry. Afterward, Pt−Pd−Co 3D porous nanostructures fabrication occurs through galvanic replacement (GR) method based on a spontaneous redox process between PtCl2, PdCl2, and CoNPs. The morphology and structure of the Pt−Pd−Co/rGO porous nanostructure film was characterized by scanning electron microscopy, energy dispersive spectroscopy and X‐ray diffraction method. The performance of the prepared electrode was investigated by various electrochemical methods including, cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic activity of the as‐prepared modified electrode with high surface areas was evaluated in anodic oxidation of ethylene glycol. The study on electrocatalytic performances revealed that, in comparison to various metal combinations in modified electrodes, trimetallic Pt−Pd−Co/rGO/GCE exhibit a lower onset potential, significantly higher peak current density, high durability and stability for the anodic oxidation of ethylene glycol. The excellent performances are attributed to the rGO as catalysts support and resulting synergistic effects of the trimetallic and appropriate characteristics of the resulted 3D porous nanostructures. Moreover, the influence of various concentrations of ethylene glycol, the potential scan rate and switching potential on the electrode reaction, in addition, long‐term stability have been studied by chronoamperometric and cyclic voltammetric methods.  相似文献   

5.
A three‐dimensional (3D) nitrogen‐doped reduced graphene oxide (rGO)–carbon nanotubes (CNTs) architecture supporting ultrafine Pd nanoparticles is prepared and used as a highly efficient electrocatalyst. Graphene oxide (GO) is first used as a surfactant to disperse pristine CNTs for electrochemical preparation of 3D rGO@CNTs, and subsequently one‐step electrodeposition of the stable colloidal GO–CNTs solution containing Na2PdCl4 affords rGO@CNTs‐supported Pd nanoparticles. Further thermal treatment of the Pd/rGO@CNTs hybrid with ammonia achieves not only in situ nitrogen‐doping of the rGO@CNTs support but also extraordinary size decrease of the Pd nanoparticles to below 2.0 nm. The resulting catalyst is characterized by scanning and transmission electron microscopy, X‐ray diffraction, Raman spectroscopy, and X‐ray photoelectron spectroscopy. Catalyst performance for the methanol oxidation reaction is tested through cyclic voltammetry and chronoamperometry techniques, which shows exceedingly high mass activity and superior durability.  相似文献   

6.
Graphene‐based hybrid nanostructures possess many advantages in the field of electrochemical energy applications. In this work, a facile and efficient hydrothermal approach has been developed for the preparation of NiFe alloy nanoparticles/rGO hybrid nanostructures, in which the nanoparticles are well combined with rGO nanosheets and the size of the nanoparticles is about 100 nm. Moreover, the electrochemical oxygen evolution reaction (OER) tests confirmed that the obtained NiFe/rGO hybrid nanostructures possess notably higher activity than both the rGO‐free NiFe nanoparticles and pure Ni/rGO hybrids, and the optimal NiFe ratio is 2:1. The OER overpotential at 20 mA cm?1?2 with Ni2Fe/rGO is as low as 0.285 V, which is 96 mV lower than that of pure Ni/rGO hybrids. Meanwhile, the Ni2Fe/rGO catalyst has excellent stability. Therefore, this work contributes a facile and efficient method to prepare a NiFe alloy nanoparticles/rGO hybrid structure for potential applications in the field of electrochemical energy devices, such as electrochemical water splitting cells, rechargeable metal/air batteries, etc.  相似文献   

7.
《Electroanalysis》2018,30(8):1811-1819
Novel copper‐palladium nanoparticles modified glassy carbon electrodes (Cu−Pd/GC) with enhanced nonenzymatic sensing for glucose were facilely prepared by one‐step electrodeposition. The structure and composition of the prepared nanoparticles were characterized by XRD, SEM, TEM and EDS, respectively. The electrode modified process was characterized by electrochemical impedance spectroscopy. Cyclic voltammetry and chronoamperometric experiments were used to evaluate the electrocatalytic activities of the electrodes toward glucose. The surface morphology and the electrocatalytic activities of Cu−Pd/GC was compared to Pd and Cu nanoparticles modified glassy carbon electrodes (Pd/GC and Cu/GC), respectively. Thanks to homogeneous distribution of Cu−Pd nanoparticles and the synergistic effect of Cu and Pd atoms, Cu−Pd/GC exhibited the highest sensitivity (298 μA mM−1 cm−2) and the widest linear amperometric response (0.01 mM to 9.6 mM, R2=0.996) toward glucose compared to Pd/GC and Cu/GC. The detection limit of Cu−Pd/GC was 0.32 μM (S/N=3). In addition, the as‐prepared Cu−Pd/GC glucose sensor also exhibited exceptional capabilities of anti‐interference, reproducibility and long‐term stability. The as‐prepared sensor was also evaluated for determination of glucose concentration in human blood serum samples, which exhibited high reliability and accuracy, having great potential in clinical application.  相似文献   

8.
We prepared a non‐covalently coupled hybrid of reduced graphene oxide (rGO)‐doped graphitic carbon nitride (g‐C3N4) by freezing‐assisted assembly and calcination. Fourier transform infrared, Raman and X‐ray photoelectron spectroscopies and transmission electron microscopy confirmed that rGO was incorporated into the bulk g‐C3N4, which was an ideal support for loading Pd nanoparticles. The Pd nanoparticles with an average size of 4.57 nm were uniformly dispersed on the rGO‐doped g‐C3N4 surface. The layered structure provided large contact area of g‐C3N4 with rGO, further accelerating the electron transfer rate and inhibiting electron–hole recombination. Consequently, compared with Pd/rGO/g‐C3N4 and Pd/g‐C3N4, the Pd/rGO‐doped g‐C3N4 showed a prominent catalytic activity for visible‐light‐driven photocatalytic Suzuki–Miyaura coupling at ambient temperature. The Pd/rGO‐doped g‐C3N4 exhibited very high stability after six consecutive cycles with minimal loss of catalytic activity.  相似文献   

9.
Core‐shell carbon‐coated LiFePO4 nanoparticles were hybridized with reduced graphene (rGO) for high‐power lithium‐ion battery cathodes. Spontaneous aggregation of hydrophobic graphene in aqueous solutions during the formation of composite materials was precluded by employing hydrophilic graphene oxide (GO) as starting templates. The fabrication of true nanoscale carbon‐coated LiFePO4‐rGO (LFP/C‐rGO) hybrids were ascribed to three factors: 1) In‐situ polymerization of polypyrrole for constrained nanoparticle synthesis of LiFePO4, 2) enhanced dispersion of conducting 2D networks endowed by colloidal stability of GO, and 3) intimate contact between active materials and rGO. The importance of conducting template dispersion was demonstrated by contrasting LFP/C‐rGO hybrids with LFP/C‐rGO composites in which agglomerated rGO solution was used as the starting templates. The fabricated hybrid cathodes showed superior rate capability and cyclability with rates from 0.1 to 60 C. This study demonstrated the synergistic combination of nanosizing with efficient conducting templates to afford facile Li+ ion and electron transport for high power applications.  相似文献   

10.
Monodisperse bimetallic Pd–Cu nanoparticles with controllable size and composition were synthesized by a one‐step multiphase ethylene glycol (EG) method. Adjusting the stoichiometric ratio of the Pd and Cu precursors afforded nanoparticles with different compositions, such as Pd85–Cu15, Pd56–Cu44, and Pd39–Cu61. The nanoparticles were separated from the solution mixture by extraction with non‐polar solvents, such as n‐hexane. Monodisperse bimetallic Pd–Cu nanoparticles with narrow size‐distribution were obtained without the need for a size‐selection process. Capping ligands that were bound to the surface of the particles were removed through heat treatment when the as‐prepared nanoparticles were loaded onto a Vulcan XC‐72 carbon support. Supported bimetallic Pd–Cu nanoparticles showed enhanced electrocatalytic activity towards methanol oxidation compared with supported Pd nanoparticles that were fabricated according to the same EG method. For a bimetallic Pd–Cu catalyst that contained 15 % Cu, the activity was even comparable to the state‐of‐the‐art commercially available Pt/C catalysts. A STEM‐HAADF study indicated that the formation of random solid‐solution alloy structures in the bimetallic Pd85–Cu15/C catalysts played a key role in improving the electrochemical activity.  相似文献   

11.
Low cost, high activity and selectivity, convenient separation, and increased reusability are the main requirements for noble‐metal‐nanocatalyst‐catalyzed reactions. Despite tremendous efforts, developing noble‐metal nanocatalysts to meet the above requirements remains a significant challenge. Here we present a general strategy for the preparation of strongly coupled Fe3O4 and palladium nanoparticles (PdNPs) to graphene sheets by employing polyethyleneimine as the coupling linker. Transmission electron microscopic images show that Pd and Fe3O4 nanoparticles are highly dispersed on the graphene surface, and the mean particle size of Pd is around 3 nm. This nanocatalyst exhibits synergistic catalysis by Pd nanoparticles supported on reduced graphene oxide (rGO) and a tertiary amine of polyethyleneimine (Pd/Fe3O4/PEI/rGO) for the Tsuji–Trost reaction in water and air. For example, the reaction of ethyl acetoacetate with allyl ethyl carbonate afforded the allylated product in more than 99 % isolated yield, and the turnover frequency reached 2200 h?1. The yield of allylated products was 66 % for Pd/rGO without polyethyleneimine. The catalyst could be readily recycled by a magnet and reused more than 30 times without appreciable loss of activity. In addition, only about 7.5 % of Pd species leached off after 20 cycles, thus rendering this catalyst safer for the environment.  相似文献   

12.
One‐pot synthesis of carbon‐supported Pd‐Au alloy nanoparticles with well‐defined dendritic shape (Pd‐Auden/C) was achieved by co‐reduction of K2PdCl4/HAuCl4 mixtures in a molar ratio of 1:1 with hydrazine in the presence of Vulcan XC‐72R. The prepared Pd‐Auden/C exhibited significantly enhanced performance in the electrocatalytic oxidation of ethanol compared with dendritic Pd nanoparticles and a commercial Pd/C catalyst. Pd‐Auden/C even showed higher durability in electro‐oxidation of ethanol than the supported catalyst prepared by the deposition of presynthesized dendritic Pd‐Au nanoparticles on the carbon support. The experimental results clearly indicate that enhanced interaction between nanoparticle catalysts and carbon support through the one‐pot synthesis protocol can improve the durability of the electrocatalysts.  相似文献   

13.
In this study, a new glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) on platinum nanoparticles (Pt NPs) decorated reduced graphene oxide (rGO)/Zn‐MOF‐74 hybrid nanomaterial. Herein, the biosensor fused the advantages of rGO with those of porous Zn‐MOF and conductive Pt NPs. This has not only enlarged the surface area and porosity for the efficient GOx immobilization and faster mass transport, but also provided favorable electrochemical features such as high current density, remarkable electron mobility through metal nanoparticles, and improved electron transfer between the components. The GOx‐rGO/Pt NPs@Zn‐MOF‐74 coated electrode displayed a linear measurement range for glucose from 0.006 to 6 mM, with a detection limit of 1.8 μM (S/N: 3) and sensitivity of 64.51 μA mM?1 cm?2. The amperometric response of the enzyme biosensor demonstrated the typical behavior of Michaelis‐Menten kinetics. The obtained satisfying sensitivity and measurement range enabled fast and accurate glucose measurement in cherry juice using the fabricated biosensor. The water‐stable Zn‐MOF‐74 demonstrated higher enzyme loading capacity and can be potent supporting material for biosensor construction.  相似文献   

14.
An electrochemical sensor for detection of three monohydroxylated polycyclic aromatic hydrocarbons (OH?PAHs) was fabricated by electrochemical reduction of graphene oxide (E‐rGO) on screen‐printed electrode (SPE). The E‐rGO film presents typical wrinkled structure with porous and cavity‐like nanostructure, providing large surface area, effective π‐electron system and high electrical conductivity. The developed E‐rGO/SPE sensor exhibits outstanding sensing performance for the target OH?PAHs, 2‐hydroxynaphthalene, 3‐hydroxyphenanthrene, and 1‐hydroxypyrene, within a linear range varying from 50–800 nM, 50–1150 nM, and 100–1000 nM, and with a limit of detection (LOD) of 10.1 nM, 15.3 nM, and 20.4 nM (S/N=3), respectively. The electrochemical sensor possesses excellent stability, acceptable reproducibility, and good anti‐interference ability. Additionally, the proposed sensor can be applied to the analysis of OH?PAHs in the urine samples with recoveries of 98.1–105.9 %.  相似文献   

15.
Monodisperse bimetallic Pd-Cu nanoparticles with controllable size and composition were synthesized by a one-step multiphase ethylene glycol (EG) method. Adjusting the stoichiometric ratio of the Pd and Cu precursors afforded nanoparticles with different compositions, such as Pd(85)-Cu(15), Pd(56)-Cu(44), and Pd(39)-Cu(61). The nanoparticles were separated from the solution mixture by extraction with non-polar solvents, such as n-hexane. Monodisperse bimetallic Pd-Cu nanoparticles with narrow size-distribution were obtained without the need for a size-selection process. Capping ligands that were bound to the surface of the particles were removed through heat treatment when the as-prepared nanoparticles were loaded onto a Vulcan XC-72 carbon support. Supported bimetallic Pd-Cu nanoparticles showed enhanced electrocatalytic activity towards methanol oxidation compared with supported Pd nanoparticles that were fabricated according to the same EG method. For a bimetallic Pd-Cu catalyst that contained 15?% Cu, the activity was even comparable to the state-of-the-art commercially available Pt/C catalysts. A STEM-HAADF study indicated that the formation of random solid-solution alloy structures in the bimetallic Pd(85)-Cu(15)/C catalysts played a key role in improving the electrochemical activity.  相似文献   

16.
A flexible composite paper Fe?Cu‐based metal‐organic framework (MOF)/reduced graphene oxide (rGO) (Fe?CuMOF/rGO) electrode was prepared by using a simple electrochemical method for the simultaneous detection of catechol (CC) and resorcinol (RC). Free‐standing, flexible and double‐sided Fe?CuMOF/rGO composite paper was obtained by applying the electrochemical deposition process on the rGO paper electrode in the solution containing Fe?CuMOF composite. The morphological analysis of Fe?CuMOF/rGO composite paper showed that sea urchin‐like structures formed on the rGO electrode surface consist of numerous sharp‐edged nanorods of Fe?CuMOF. Flexible Fe?CuMOF/rGO paper electrode exhibited high sensitivity, wide linear range and low detection limit for the simultaneous determination of CC and RC. The linear ranges of concentration for CC and RC were 0.1–800 and 0.1–720 μM, respectively, and the corresponding limits of detection (S/N=3) were 0.016 and 0.020 μM. The outstanding performance of this flexible electrode could be attributed to the sharp‐edged urchin‐like Fe?CuMOF structures which provide an increment of the surface area and the electrochemical activity of the composite paper electrode. Stability tests showed that Fe?CuMOF/rGO composite paper electrode has excellent flexibility, high durability, and good reproducibility. Furthermore, this electrode exhibited high sensitivity and selectivity for the determination of CC and RC in real sample analysis.  相似文献   

17.
The article describes the preparation of supported nickel nanoparticles (NiNPs) by partial reduction of Ni,Co‐layered double hydroxide (NiCo‐LDH). The nanocomposites were characterized by X‐ray diffraction and their morphology and composition were characterized by scanning electron microscopy and transmission electron microscopy. The electrochemical properties of the nanocomposite were explored by cyclic voltammetry and amperometry, which revealed significant electrocatalytic behavior towards the oxidation of glucose. The resulted non‐enzymatic glucose sensor has a linear response to glucose in the 5.0 μM to 14.8 mM concentration range, a low detection limit of 1.6 μM, high sensitivity, and excellent selectivity.  相似文献   

18.
Nanoporous copper (NPC) obtained by dealloying CuAl alloy is used as both three-dimensional template and reducing agent for the fabrication of nanoporous PdCu alloy with hollow ligaments by a simple galvanic replacement reaction with H2PdCl4 aqueous solution. Electron microscopy and X-ray diffraction characterizations demonstrate that after the replacement reaction, the ligaments become hollow tubular structure and the ligament shell is also comprised of small pores and nanoparticles with a typical size of ∼4 nm (third order porosity). The as-prepared nanotubular mesoporous PdCu alloy (NM-PdCu) structure exhibits remarkably improved electrocatalytic activity towards the oxidation of formic acid and H2O2 compared with nanoporous Pd (NP-Pd), and can be used for sensitive electrochemical sensing applications. After coupled with glucose oxidase (GOx), the enzyme modified NM-PdCu electrode can sensitively detect glucose over a wide linear range (0.5–20 mM).  相似文献   

19.
Hollow structures have attracted ever‐growing interest owing to their various excellent properties. However, a facile strategy for their fabrication is still desired. Herein, Pd? Pt alloy with three different morphologies, that is, cubes, hollow cubes, and truncated octahedrons, is synthesized by using a one‐pot, template‐free method. The mechanism and dynamics of this system is also studied in detail. In particular, the hollow cubic structure represents enhanced catalytic activity in both coupling reactions and in the electrochemical oxidation of formic acid.  相似文献   

20.
The detection of glucose at low concentrations using electrochemical sensors is of great importance due to the possibility of using different human body fluids than blood, such as e. g. urine, saliva, sweat or tears. The interest behind those biofluids is related to their utility in non‐invasive sugar determination. In this work, we present flexible, fully biocompatible electrode material based on Au nanoparticles immobilized onto titanium dimples. Au?Ti heterostructures were obtained via electrochemical anodization of titanium foil in presence of fluoride anions followed by chemical etching, magnetron sputtering of gold and subsequent thermal dewetting in continuous regime. In the last step of fabrication, electrodes were modified by permselective Nafion membrane. The selection of the best electrode material among different configurations was carried out basing on the electrochemical activity in the contact with 5 mM glucose dissolved in neutral air‐saturated 0.1 M PBS. For the 10 nm Au dewetted gold film, limit of detection of 30 μM and high sensitivity of 93 mA cm?2 mM?1 were achieved. Application of Nafion membrane caused complete inhibition of the impact of various interference species onto the glucose detection. Good selectivity and repeatability combined with the resistance to prolonged mechanical stress suggest that prepared material can be used in non‐invasive glucose sensing.  相似文献   

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