摘要:
Here we report a facile and cost-effective preparation of nickel nanoparticle S/Nitrogen-carbon nanohybrid (Ni NPS/N-C) based on formamide condensation and carbonization, used for highly sensitive and selective electrochemical determination of tryptophan (Trp) in practical samples. The crystallographic phase, surface morphology, elemental distribution, and chemical state of the Ni NPS/N-C nanohybrid were analyzed by XRD, SEM, TEM, EDS, XPS, FTIR, TGA and Raman spectra. The results show that high content of Ni NPs (6.62 wt%) were distributed in the nanohybrid, and a large number of bamboo-like nanotubes were formed during pyrolysis, which dramatically increases the specific surface area, and remarkably promotes the electrical conductivity as well as the catalytic activity of the nanohybrid. The electrochemical behavior of Trp was investigated on the nanohybrid modified carbon paste electrode (Ni NPS/N-C/CPE) and the measurement parameters were optimized. As expected, the modified electrode can remarkably enhance the electrochemical oxidation signal of Trp. Under the optimal experimental conditions, a linear relationship in the range of 0.01-20 mu M and 20-80 mu M for Trp was established with detection limit of 5.7 nM (S/N = 3). Finally, the proposed sensor was practically applied by evaluation and determination of Trp from various sourcing samples including human serum and pharmaceutical samples.
作者机构:
[Deng, Peihong; Li, Junhua] Hengyang Normal Univ, Key Lab Funct Organometall Mat Hunan Prov Univ, Dept Chem & Mat Sci, Key Lab Funct Met Organ Cpds Hunan Prov, Hengyang 421008, Peoples R China.;[He, Quanguo; Tian, Yaling; Wu, Yiyong; Xiao, Jingyun; Feng, Jinxia] Hunan Univ Technol, Sch Life Sci & Chem, Zhuzhou 412007, Peoples R China.
通讯机构:
[Peihong Deng] D;[Quanguo He] S;School of Life Science and Chemistry, Hunan University of Technology, Zhuzhou 412007, China<&wdkj&>Department of Chemistry and Material Science, Hengyang Normal University, Key Laboratory of Functional Metal-Organic Compounds of Hunan Province, Key Laboratory of Functional Organometallic Materials of Hunan Provincial Universities, Hengyang 421008, China
摘要:
In recent years, small-sized electrodes have drawn widespread attraction in electroanalysis due to high sensitivity, rapid response and low cost. Hereby, a sub-millimeter paste electrode with inner diameter of 0.8 mm was prepared by combining the excellent properties of reduced graphene oxide (rGO) and acetylene black (AB), and the electrochemical behavior of tyrosine (Tyr) on the modified electrode (denoted as rGO/ABPE) was investigated in detail. The electrochemical responses obtained on the sub-millimeter rGO/ABPE were compared with that obtained on a conventional size electrode with diameter of 3 mm. The results showed that the 0.8 mm one has better performance than that of 3 mm. Compared with the paste electrode made of graphite powder, the oxidation peak current of Tyr increased significantly due to the synergistic effect of rGO and AB. Under the optimized experimental conditions, the calibration curve of Tyr showed a linear relationship between 0.1 and 100 ?M (R = 0.9995) with good sensitivity of 3.314 ?A ?M-1 cm-2, and the detection limit was 0.06 ?M. By comparison with conventional size electrode, the detection of Tyr on the sub-millimeter electrode shows higher sensitivity, wider linear range and lower detection limit. In addition, the excellent reproducibility, stability and selectivity of the sub-millimeter rGO/ABPE make it suitable for Tyr analysis in both food and biological samples.
摘要:
Metal-organic frameworks (MOF) are recently developed coordination porous materials, and their unique structures are very conducive to catalytic reactions. In this paper, p-benzenedicarboxylic acid (PBA)-Ni(2+) MOF materials (denoted as PBA-Ni-x, where x represents the initial ratio of PBA to Ni(2+) ) were synthesized by a hydrothermal method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N(2) gas adsorption. H(2) gas was produced using the synthesized MOF as a photocatalyst and Eosin Y as a photosensitizer. The dependence of the special surface area and thickness of the nanosheets of Ni-MOF on the initial ratio of PBA to Ni(2+) (PBA/Ni(2+) ) was investigated. The BET surface areas of PBA-Ni-1 PBA-Ni-2 and PBA-Ni-3 are 11.00, 24.61, 13.04 m(2) /g, respectively. And the thicknesses of nanosheets are approximately 600~1000, 200~500, and 300~700 nm. Among the three materials, PBA-Ni-2 has the thinnest sheet-like structure and largest surface area. Thus, it displays the highest H(2) evolution rate of 20.0 μmol·h(-1) . The noble-metal-free hydrogen production system is valuable for the application of MOF materials in photocatalytic water splitting.
摘要:
We design a novel sulfur host composite with carbon nanotubes (CNTs) intercalated to the polyhedrons consisting of metallic cobalt and N-doped carbon derived from zeolite imidazolate framework-67 (Co-N-C/CNTs). As compared with the pristine Co-N-C, the intercalated CNTs can lead to significant enhancements of specific surface area, sulfur loading and electroconductivity, thus pronouncedly improving the overall Li-S battery performance. More specifically, the Co-N-C/CNTs/S cathode delivers an initial discharge capacity of 1440.6 mA h g(-1) at 0.1C while 1104.4 mA h g(-1) for Co-N-C/S. At 1C, the capacity decay rate of Co-N-C/CNTs/S is 0.09% per cycle after 500 cycles with the coulombic efficiency more than 98.2%, while 0.14% per cycle with the coulombic efficiency of 96.4% for Co-N-C/S. Evidently, the interpenetration of CNTs into the sulfur host materials is a simple and effective strategy to promote the Li-S battery performance.
摘要:
In this work, we demonstrate, for the first time, a low-temperature direct-sulfidization of nickel foam (NF) assisted with oxidant K2S2O8 to fabricate a novel self-supported hierarchical porous Ni3S2@NF electrode for supercapacitors. The resultant Ni3S2@NF electrode exhibits a high specific capacitance of 2519.5 mF cm(-2) at a current density of 1.0 mA cm(-2), and a rate capability of 68.5% over a current density range of 1-20 mA cm(-2). At the same time, the retention of areal specific capacitance amounts to similar to 100% of its initial capacitance at 20 mA cm(-2) after 4000 consecutive charge-discharge cycles. Moreover, an asymmetric all-solid-state supercapacitor device Ni3S2@NF//activated carbon (AC)@NF has been assembled. Remarkably, this device can afford an energy density of 32.0 Wh kg(-1) at a power density of 210.8 W kg(-1) accompanied with excellent electrochemical cyclic stability. Such outstanding supercapacitive behavior of Ni3S2@NF can be credited to its unique porous interpenetrating architecture and the robust contact of Ni3S2 and NF, which can ensure rapid ion and electron transfers for redox reactions as well as tightly contacts among active component, substrate, and electrolyte. The direct-sulfidization of metals assisted with oxidants can offer a general, scalable, and viable protocol to fabricate high-performance electrochemical materials for energy-storage applications.
摘要:
Aiming at substantially improving the electrochemical sensing performance for guanine, we bring out a novel high-efficiency electrocatalyst composed of hierarchical sea urchin-like Prussian blue@palladium core-shell heterostructures supported on nitrogen-doped reduced graphene oxide (PB-U@Pd/N-RGO). The said PB-U@Pd/N-RGO was synthesized by a new and facile wet-chemistry method without using any surfactant and template. More impressively, we demonstrate a new strategy for morphology-controlled synthesis of Prussian blue via simply tuning the ratio of N,N'-dimethyl formamide and H2O in the mixed solvent. In-depth electrochemical characterizations demonstrate the superior electrocatalytic performance of PB-U@Pd/N-RGO toward the oxidation of guanine, which benefits from the synergistic effect of component materials and its unique core-shell heterostructure. Consequently, the constructed PBU@Pd/N-RGO-based electrochemical sensor displays superb comprehensive performance for the guanine assay. To be specifical, the developed sensor exhibits wide detection range (0.01-85.0 mu W), low detection limit (2.6 nM), good reproducibility, long-term stability, high sensitivity and selectivity together with acceptable recovery (97.0-104.0%) for the assay of guanine in biological samples. Such outstanding comprehensive performance is amongst the top of reports for the electrochemical sensing of guanine, promising practical applications in biosensing fields. (C) 2019 Elsevier Ltd. All rights reserved.
摘要:
Vanillin is widely used as a flavoring and fragrance enhancer in foods. Rapid detection of vanillin is of vital significance and necessity for food safety. In this work, a sensitive voltammetric sensor to detect trace vanillin of nanomolarity in food samples was demonstrated by using manganese dioxide nanowires hybridized electrode. Firstly, a modified glassy carbon electrode was prepared using manganese dioxide nanowires functionalized reduced graphene oxide as a modifier (MnO2 NWs-rGO/GCE). Then the MnO2 NWs-rGO/GCE were characterized by scanning electron microscopy, X-ray diffraction (XRD) and cyclic voltammetry (CV). Vanillin's electrochemical behavior in the solution of 0.1 M H2SO4 was studied in detail. The results showed that the modified electrode had an electrocatalytic activity for vanillin oxidation. The adsorption capacity (Gamma(s)) and standard rate constant (k(s)) on the modified electrode were calculated by chronocoulometry (CC). Subsequently, after systematic investigation of second derivative linear sweep voltammetry (SDLSV) under the optimal conditions, the oxidation peak current was linearly correlated with vanillin concentration in the separate ranges of 0.01-20 mu M (R-2 = 0.9808) and 20-100 mu M (R-2 = 0.9964), yielding the detection limit of 6.0 nM (S/N = 3). In addition, MnO2 NWs-rGO/GCE showed the advantages of surface renewal, excellent reproducibility, good stability, and simple preparation. The method was applied to the nanomolarity determination of vanillin in commercial foods with satisfactory results.
摘要:
In this work, we developed a novel hybrid with N-doped bamboo-like carbon nanotubes combined with the CoFe alloy and its oxide (denoted as CoFe-CoFe2O4/N-CNTs) via an extremely facile one-step pyrolysis method. When applied as an electrocatalyst towards OER in 1.0 M KOH solution, CoFe CoFe2O4/N-CNTs exhibits a small overpotential of 334 mV to afford a current density of 10 mA cm(-2) associated with a low Tafel slope of 80 mV dec(-1) and long-term stability. The remarkable OER electrocatalytic performance of CoFe CoFe2O4/N-CNTs is mainly attributed to the synergistic effect between CoFe and CoFe2O4 as well as the increased active sites resulting from the introduction of N-CNTs. More impressively, the introduction of Fe can significantly cut down the usage of relatively toxic and expensive Co accompanied with the dramatic enhancement of OER electrocatalytic performance originating from the robust synergistic effect between Co and Fe. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
关键词:
Prussian blue analogues;Synthesis;Electrochemical determination;2-Nitrophenol
摘要:
In this work, three kinds of bimetallic Prussian blue analogues (PBAs), i.e. KxNi [Fe(CN)(6)]center dot nH(2)O (NiFe-PBA), KxCo [Fe(CN)(6)]center dot nH(2)O (CoFe-PBA), and KxMn [Fe(CN)(6)]center dot nH(2)O (MnFe-PBA), were synthesized by a simple precipitation method under identical conditions. Their chemical compositions, structures, morphologies, valences of transition metals, and electrochemical sensing performances for 2-nitrophenol (2-NP) are examined in details. It is found that all the prepared PBAs hold face-centered-cubic structures with near perfect cube morphologies for NiFe-PBA and CoFe-PBA and truncated cube morphology for MnFe-PBA. For the electrochemical detection of 2-NP, a wide detection range of 1.0-700.0 mu M was obtained at all PBAs modified electrodes together with the sensitivities of 443.3, 368.0, and 339.0 mu A cm(-2) mM(-1) and detection limits of 0.28, 0.46, and 0.59 mu M achieved at NiFe-PBA, CoFe-PBA, and MnFe-PBA modified electrodes, respectively. The superiority in electrochemical sensing performance of NiFe-PBA to CoFe-PBA and MnFe-PBA may stem from its higher conductivity, lager electroactive surface area, and better intrinsic catalytic property of the transition metal in its framework. Furthermore, the constructed NiFe-PBA-based sensor displays good repeatability, long-term stability, and high selectivity together with desirable recoveries (97.8-103.9%) for the assay of 2-NP in water samples. The present work is the first report on the PBAs-based electrochemical sensors for 2-NP detection, which may promise a future of PBAs or PBAs-based materials for sensing applications. (c) 2020 Elsevier Ltd. All rights reserved.