Pd nanoparticles on boron doped graphene catalyst for electrochemical detection of hydrogen peroxide prepared by electroless deposition methodEI北大核心CSCD

Taking advantage of large conjugated structure and reductivity of boron-doped graphenethe palladium nanoparticles/boron-doped graphene catalyst was prepared by electroless deposition method using boron-doped graphene as reductant and stabilizer. The average size of palladium nanoparticles highly dispersed on the surface of boron-doped graphene was about 6.5 nm. The electrochemical sensor was prepared by modifying the as-formed catalyst on the surface of glassy carbon electrode. The obtained electrochemical sensor exhibited an excellent electrochemical catalytic activity for H2 O2 . It exhibited high sensitivity with the detection limit as low as 830 nmol/L and good linearity in the range of 2.5-300 μµmol/L for detection of H2 O2 . It could be utilized for the determination of H2 O2 in milk samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Electrochemical preparation of nickel-iron hydroxide loaded on multi-walled carbon nanotubes electrode for the detection of ureaEI北大核心CSCD

A nickel-iron hydroxide/multi-walled carbon nanotubes MWCNTscomposite film electrode was prepared by electrochemical derivation of metal hexacyanoferrate in alkaline solution. MWCNTs film modified electrode was prepared by dropping methodthen Ni-Fe bimetal hexacyanoferrateNi-FeHCFnanoparticles were deposited on the surface of MWCNTs by cyclic voltammetry. This Ni-FeHCF/MWCNTs electrode was electrochemically derived in alkaline solution and a MWCNTs composite film electrodeNiOH2-FeOH3 /MWCNTs/ CCEwas obtained. The surface morphology and the electrochemical behavior of this modified electrode were characterized by scanning electron microscopeSEMand cyclic voltammetryCV. This electrode exhibited high catalytic activity for the electrochemical oxidation of urea under the synergistic action of each component. Based on thisthe non-enzymatic electrochemical sensing of urea was established. In 1.0 mol/L KOH solution the linear range of urea by amperometry was between 5.0×10−3 and 2.8 mmol/Land the detection limit was 3.6 μµmol/L. The sensitivity to urea was 54.3 μµA/mmol/L. This electrode could be used for the determination of urea in river water and human urine samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Electrochemical sensor based on f-SWCNT and carboxylic group functionalized PEDOT for the sensitive determination of bisphenol A

A simple,sensitive,and reliable method for the voltammetric determination of bisphenol A(BPA) by using carboxylic group functionalized single-walled carbon nanotubes(f-SWCNT)/carboxylic-functionalized poly(3,4-ethylenedioxythiophene)(PC4) complex modified glassy carbon electrode(GCE) has been successfully developed.The electrochemical behavior of BPA at the surface of the modified electrode is investigated by electrochemical techniques.The cyclic voltammetry results show that the as-prepared electrode exhibits strong catalytic activity toward the oxidation of BPA with a well-defined anodic peak at 0.623 V in PBS(0.1 mol/L,pH 7.0).The surface morphology of the 3D network of composite film is beneficial for the adsorption of analytes.Under the optimized conditions,the oxidation peak current is proportional to BPA concentration in the range between 0.099 and 5.794 μmol/L(R~2 = 0.9989),with a limit of detection of 0.032 μmol/L(S/N = 3).The enhanced performance of the sensor can be attributed to the excellent electrocatalytic property of/-SWCNT and the extraordinary conductivity of PC4.Furthermore,the proposed modified electrode displays high stability and good reproducibility.The good result on the voltammetric determination of BPA also indicates that the asfabricated modified electrode will be a good candidate for the electrochemical determination and analysis of BPA.     

A nonenzyme glucose sensor based on Cu/Ni/CMWCNTs nanocompositesEI北大核心CSCD

Copper-nickel bimetallic nanoparticles decorated on carboxylated multi-walled carbon nanotubes （Cu/Ni/CMWCNTs）were prepared by using a simple one-pot solvothermal method,which was then employed to construct a highly sensitive non-enzymatic glucose sensor. The modified electrode showed high sensitivity and stability in glucose detection,which was mainly attributed to the synergistic effect of the compact copper-nickel nanocomposite and carboxylated multi-walled carbon nanotubes that possessing high specific surface area to increase the number of active sites and to improve the electrocatalytic activity of the modified electrode. The phase structure and morphology of the material were characterized by X-ray diffraction and scanning electron microscope; the electrochemical performance of the sensor was studied by cyclic voltammetry and chronoamperometry. The sensor had a sensitivity of 1949.1 μµA·L/（mmol·cm2）for glucose detection in the linear range of 1.0-8000 μµmol/L at a potential of 0.55 V,and the detection limit was 0.2 μµmol/L. The sensor was also applied to measure the concentration of glucose in serum samples. The developed nanocomposites sensor has the potential prospect to monitor blood glucose. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Rapid detection of chlorpheniramine maleate by an electrochemical sensor based on metal-organic frameworks CHP@Cu3（BTC）2 /MWCNTsEI北大核心CSCD

Copper hydroxyphosphate@metal-organic frameworks/multi-wall carbon nanotube composites （CHP@Cu3 （BTC）2 /MWCNTs）were prepared by a new in-situ template method and then an electrochemical sensor was developed based on the composites. The crystal structure and morphology of the material were characterized by X-ray diffraction and scanning electron microscope. Cyclic voltammetry and linear sweep voltammetry were used to study the electrochemical catalytic performance，and the determination conditions were optimized. The rapid and sensitive detection of chlorphenamine maleate was realized. There was a good linear relationship between the oxidation peak current and concentration of chlorphenamine maleate in the ranges from 5 to 100 µμmol/L and from 150 to 800 µμmol/L，and the linear equations were as Ipa （µμA）=0.1559c（µμmol/L）-0.3533 （R2 =0.9973）and Ipa （µμA）=0.02328c（µμmol/L）+16.63（R2 =0.9594），and the detection limit was 1.67 µμmol/L. The recoveries of the actual drug ranged from 91.0% to 109.1%. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

银纳米颗粒的合成及用于抗癌药氟他胺的电化学检测（英文）

Ag nanoparticles were synthesized on the surface of a glassy carbon electrode modified with p‐tert‐butylcalix[4]arene and p‐tert‐butylcalix[6]arene by the deposition of Ag+ at an open circuit potential followed by the electrochemical reduction of the Ag+.The presence of the calixarene layer on the electrode surface controlled the particle size and prevented agglomeration.Cyclic voltam‐metry showed that the Ag nanoparticles on the modified glassy carbon electrode had good catalytic ability for the reduction of flutamide.The effects of calixarene concentration,potential applied for the reduction of Ag+,number of calixarene layers,and p H value on the electrocatalytic activity of the Ag nanoparticles were investigated.The modified electrode had a linear range in differential pulse voltammetry of 10-1000 μmol/L with a detection limit of 9.33 μmol/L for flutamide at an S/N = 3.The method was applied to the detection of flutamide in practical samples.     

Sensitive voltammetric determination of xanthinol nicotinate at a carbon nanotubes-ionic liquid gel modified electrode

The electrochemistry of xanthinol nicotinate(Xan) was studied by cyclic voltammetry at a glassy carbon electrode modified by a gel containing multi-walled carbon nanotubes(MWNTs) and room-temperature ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate(BMTMPF_6).The modified electrode exhibited good promotion to the electrochemical oxidation of Xan and an ultrasensitive electrochemical method was proposed for the determination of Xan.This method was successfully applied to the determination of...     

Wavelength-sensitive photocatalytic H_2 evolution from H_2S splitting over g-C_3N_4 with S,N-codoped carbon dots as the photosensitizer

Photocatalytic splitting of hydrogen sulfide(H2S) for hydrogen evolution is a promising method to solve the energy and environmental issues.In this work,S,N-codoped carbon dots(S,N-CDs)/graphitic carbon nitride(g-C3N4) nanosheet is synthesized by hydrothermal method as an efficient photocatalyst for the decomposition of H2S.In addition to the characterization of the morphology and structure,chemical state,optical and electrochemical performances of S,N-CDs/g-C3N4,hydrogen evolution tests show that the activity of g-C3N4 is improved by introducing S,N-CDs,and the enhancement depends strongly on the wavelength of incident light.The photocatalytic hydrogen production rate of S,N-CDs/g-C3N4 composite reaches 832 μmol g-1h-1, which is 38 times to that of g-C3N4 under irradiation at 460 nm.Density functional theory calculations and electron paramagnetic resonance as well as photoluminescence technologies have altogether authenticated that the unique wavelength-dependent photosensitization of S,N-CDs on g-C3N4;meanwhile,a good match between the energy level of S,N-CDs and g-C3N4 is pivotal for the effective photocatalytic activity.Our work has unveiled the detailed mechanism of the photocatalytic activity enhancement in S,N-CDs/g-C3N4 composite and showed its potential in photocatalytic splitting of H2S for hydrogen evolution.     

Etching graphitic carbon nitride by acid for enhanced photocatalytic activity toward degradation of 4-nitrophenol

Graphitic carbon nitride （g-C3N4） with high photocatalytic activity toward degradation of 4-nitrophenol under visible light irradiation was prepared by HCI etching followed by ammonia neutralization. The structure, morphology, surface area, and photocatalytic properties of the prepared samples were studied. After treatment, the size of the g-C3N4 decreased from several micrometers to several hundred nanometers, and the specific area of the g-C3N4 increased from 11.5 m2/g to 115 m2/g. Meanwhile, the photocatalytic activity of g-C3N4 was significantly improved after treatment toward degradation of 4- nitrophenol under visible light irradiation. The degradation rate constant of the small particle g-C3N4 is 5.7 times of that of bulk g-C3N4, which makes it a promising visible light photocatalyst for future applications for water treatment and environmental remediation.     

纳米TiO2膜用于光催化氧化测定化学需氧量的研究

A photocatalytic oxidation method for determination of chemical oxygen demand （COD） using nano-TiO2 film, based on the use of a nano-TiO2-Ce（SO4）2 system and electrochemical detection, was proposed. The technique was originated from the direct determination of the Ce（Ⅲ） concentration change resulting from photocatalytic oxidation of organic compounds. Ce（Ⅲ）, which was produced by photocatalytic reduction of Ce（SO4）2, could be measured at a multi-walled carbon nanotubes （MWNT） chemically modified electrode （CME）. The COD values by this method were calculated from the differential pulse voltammetry （DPV） current of Ce（Ⅲ） at the CME. Under the optimal operation conditions, the detection limit of 0.5 mg·L^-1 COD with the linear range of 1-600 mg·L^-1 was achieved. This method was also applied to determination of various COD of ground water and wastewater samples. The resuits were in good agreement with those from the conventional COD methods, i.e., permanganate and dichromate ones.     

Simultaneous determination of dihydroxybenzene isomers utilizing a thiadiazole film electrode

The present study reports a sensitive electro-analytical method for the simultaneous determination of dihydroxybenzene isomers by using a thiadiazole film electrode, which was readily prepared by electropolymerization of 2,5-dimercapto-1,3,4-thiadiazole on a glassy carbon electrode with cyclic voltammetry. The functionalized electrode has a distinguishable and sensitive response to dihydroxybenzene isomers. Under the optimized conditions, the linear stripping peak currents showed good linear relationships with hydroquinone, catechol and resorcinol at concentration ranges 0.50-120, 0.50-110 and 1.00-110 μmol/L, and the detection limits are 0.1, 0.1 and 0.3 μmol/L, respectively. The proposed method is applicable to the simultaneous determination of dihydroxybenzene isomers in real samples with the relative standard deviations of less than 5.7% and the recovery rates of 95.6%-106%. The constructed electrode is characterized by simple preparation, good selectivity, and high sensitivity advantages.     

Electrochemical Reaction Mechanism of Phenacetin at a Carboxylated Multiwall Carbon Nanotube Modified Electrode and Its Analytical Applications

A novel type of carboxylated multiwalled carbon nanotube modified electrode（c-MWCNTs/GCE） was constructed and the electrochemical properties of phenacetin（PHE） at it were studied. In a buffer solution of 0.1 mol/L HAc-NaAc（pH=5.3）, PHE exhibited a couple of quasi-reversible redox peaks and an anodic peak in the poten- tial range of 0.2--1.2 V at c-MWCNTs/GCE. The peak current was proportional to the concentration of PHE in the range of 4.0× 10^-6_ 1.0 × 10^-4 mol/L with a detection limit of 1.0× 10^-6 mol/L（S/N=3）. The c-MWCNTs/GCE showed excellent repeatability and stability and the electrochemical reaction mechanism of PHE was proposed. This method was used to determine the content of PHE in medical tablets and the recovery was determined to be 96.5%--104.2% by means of a standard addition method.     

Fabrication of CeO2 Nanoparticle Modified Glassy Carbon Electrode for Ultrasensitive Determination of Trace Amounts of Uric Acid in Urine

The preparation of a glassy carbon electrode modified by CeO2 nanoparticles was described, which was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. In pH 6.0 buffer, the CeO2 nanoparticle modified electrode （CeO2 NP/GC） gave an excellent electrocatalytic activity for the oxidation of uric acid （UA）. The catalytic current of UA versus its concentration had a good linear relation in the range of 2.0 × 10^-7-5.0 × 10^- 4 mol/L, with the correlation coefficient of 0.9986 and detection limit of 1.0 ×10^-7 mol/L. The modified electrode can be used for the determination of UA in urine, which can tolerate the interference of ascorbic acid up to 1000-fold. The method was simple, quick and sensitive.     

在色氨酸存在下利用多壁碳纳米管糊电极和萘酚介质构成的伏安传感器测定N-乙酰半胱氨酸(英文)

A multiwall carbon nanotube modified electrode prepared by incorporating multiwall carbon nanotubes in the electrode of a sensor and naphthol green as a homogeneous mediator was used as a voltammetric sensor for the determination of N‐actylcysteine(N‐AC) in the presence of trypto-phan(Trp). The voltammograms of differential pulse voltammetry of N‐AC in a mixture with Trp were separated from each other by a potential difference of 200 mV, which allowed the determina-tion of both N‐AC and Trp simultaneously. Under the optimum conditions, the electrocatalytic cur-rents increased linearly with N‐AC concentration in the range of 0.25–400 μmol/L(two linear seg-ments with different slopes). The detection limit for N‐AC was 0.08 μmol/L. The kinetic parameters of the system were determined using electrochemical methods. The method was applied for the determination of N‐AC in drug and urine samples.     

Analysis of Vitamin K3 by a Fluorescent Spectroelectrochemistry Method

A simple and sensitive spectroelectrochemistry method for the determination of vitamin K 3 was developed by combining electrolysis and fluoremetry. This method was based on that vitamin K 3 was reduced at a glassy carbon electrode, and its product with characteristic fluorescence at 420 nm was determined with excitation wavelength at 309 nm. Under optimized electrochemical reaction conditions and fluorescent experiment parameters, the fluores-cence intensity was proportional to the concentration of vitamin K 3 in a range from 3.50×10 ?7 to 1.05×10 ?5 mol/L with a correlation coefficient of 0.9991, and detection limit was estimated to be 7.50×10 ?8 mol/L at a signal/noise ra-tio of 3. The relative standard deviation was less than 4.3%(n=5) and the recovery was in a range of 97%―105% for the determination of vitamin K 3 in pharmaceutical preparations. The result is satisfactory for the determination of vi-tamin K 3 as comparison to that from HPLC method.     

方波伏安法测定新型修饰多壁碳纳米管糊电极对肼的电催化氧化(英文)

The application of p-aminophenol as a suitable mediator, as a sensitive and selective voltammetric sensor for the determination of hydrazine using square wave voltammetric method were described. The modified multiwall carbon nanotubes paste electrode exhibited a good electrocatalytic activity for the oxidation of hydrazine at pH = 7.0. The catalytic oxidation peak currents showed a linear dependence of the peaks current to the hydrazine concentrations in the range of 0.5–175 μmol/L with a correlation coefficient of 0.9975. The detection limit (S/N = 3) was estimated to be 0.3 μmol/L of hydrazine. The relative standard deviations for 0.7 and 5.0 μmol/L hydrazine were 1.7 and 1.1%, respectively. The modified electrode showed good sensitivity and selectivity. The diffusion coefficient (D = 9.5 × 10–4 cm2/s) and the kinetic parameters such as the electron transfer coefficient (α = 0.7) of hydrazine at the surface of the modified electrode were determined using electrochemical approaches. The electrode was successfully applied for the determination of hydrazine in real samples with satisfactory results.     

Determination of Metamizole Sodium by Cyclic Voltammetry Under Microwave Activation

<正>Microwave radiation was applied to the detection of metamizoie sodium by cyclic voltammetry.The electrochemical characteristics of metamizoie sodium were studied by cyclic voltammetry at GC electrode under microwave radiation and a considerable current enhancement was observed for metamizoie sodium in aqueous 0.05 mol/L H_2SO_4.Under the optional conditions,metamizoie sodium was determined in the absence and presence of microwave activation.In the absence of microwave activation cyclic voltammogram of metamizoie sodium shows good linear relationship in a concentration range of 8.0×10~(-5)—1.0×10~(-3) mol/L in aqueous 0.05 mol/L H_2SO_4 with a detection limit of 6.75×10~(-6) mol/L(S/N=3) and the equation of linear regression is I_p=12.973c-0.1905(R~2=0.9996,n=6);in the presence of 80 W microwave activation cyclic voltammogram of metamizoie sodiumin shows good linear relationship in a concentration range of 4.0×10~(-5)—1.0×10~(-3) mol/L in aqueous 0.05 mol/L H_2SO_4 with a detection limit of 4.41×10~(-6)mol/L(S/N=3) and the equation of linear regression is I_p=25.107c-0.1193(R~2=0.9973,n=7).The current in the presence of 80 W microwave activation increases to about 2 orders of magnitude compared with that in the absence of microwave activation.The proposed method in the presence of microwave activation showed high selectivity and sensitivity,and the sampling of the disposal method is simple.The method was verified by the determination of Metamizoie Sodium tablet with satisfactory results.     

Three-element doped carbon dots for the detection of p-nitrophenolEI北大核心CSCD

Based on the characteristics that heteroatom doping can improve the luminescence performance of carbon dotsa new type of three-element co-doped carbon dots NSSi-CDswas prepared. The synthesis conditions were optimizedand the morphologystructure and luminescence properties of NSSi-CDs were characterized. NSSi-CDs can emit 450 nm blue fluorescence under excitation at 370 nmand the fluorescence quantum yield reached 11%. The study found that p-nitrophenol PNPhas a strong fluorescence quenching effect on NSSi-CDsand thus a new method for the determination of PNP with NSSi-CDs fluorescent probe was constructed. When the concentration of PNP was in the range of 0.9-60 μµmol/Lit had a good linear relationship with the fluorescence quenching efficiencyF0 /Fand the detection limit was 0.36 μµmol/L. This method was used to determine PNP in actual water samples with good recoveries of 90.6%-95.2%. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

在3,4-二羟基肉桂酸介质中以多壁碳纳米管为传感器电催化检测L-半胱氨酸(英文)

A highly sensitive electrochemical sensor was prepared for the determination of L-cysteine using a modified multiwall carbon nanotubes paste electrode in the presence of 3,4-dihydroxycinnamic acid(3,4-DHCA) as a mediator, based on an electrocatalytic process. The results indicate that the electrode is electrocatalytically efficient for the oxidation of L-cysteine in the presence of 3,4-DHCA. The interaction between the mediator and L-cysteine can be used for its sensitive and selective determination. Using chronoamperometry, the catalytic reaction rate constant was calculated to be 2.37 × 102 mol–1 L s–1. The catalytic peak current was linearly dependent on the L-cysteine concentration in the range of 0.4–115 μmol/L. The detection limit obtained by linear sweep voltammetry was 0.25 μmol/L. Finally, the modified electrode was examined as a selective, simple, and precise new electrochemical sensor for the determination of L-cysteine in real samples.     

可见光下改性的纳米孔二氧化硅(LUS-1)光催化苯直接羟基化合成苯酚(英文)

Fe-g-C3N4-LUS-1 was prepared by the thermal decomposition of dicyandiamide inside the pores of LUS-1 under an inert atmosphere.It was used as a photocatalyst for the hydroxylation of benzene to phenol in sunlight.The catalysts were characterized by Fourier transform infrared spectroscopy,N2 adsorption-desorption,X-ray diffraction,and scanning electron microscopy.In Fe-g-C3N4-LUS-1,a single layer of graphitic carbon nitride(g-C3N4) was formed on the surface of LUS-1.The photocatalytic activity of the iron containing g-C3N4 based catalysts was investigated,and the catalytic activity was remarkably enhanced when the reaction condition was changed from dark to sunlight.The best result was obtained with 20%Fe-g-C3N4-LUS-1 in sunlight.