还原氧化石墨烯/TiO2复合材料在钠离子电池中的电化学性能

二氧化钛(TiO₂)作为有前景的钠离子电池负极材料, 具有良好的循环稳定性, 但由于其导电率较低, 而导致容量和倍率性能不佳限制了其实际应用. 本文采用喷雾干燥技术制备了氧化石墨烯/纳米TiO₂复合材料(GO/TiO₂), 通过热处理获得还原氧化石墨烯/TiO₂复合材料(RGO/TiO₂). 电化学测试结果表明, 还原氧化石墨烯改性的RGO/TiO₂复合材料的电化学性能得到显著提升, RGO含量为4.0%(w)的RGO/TiO₂复合材料在各种电流密度下的可逆容量分别为183.7 mAh·g^-1 (20 mA·g^-1), 153.7 mAh·g^-1 (100 mA·g^-1)和114.4 mAh·g^-1 (600mA·g^-1), 而纯TiO₂的比容量仅为93.6 mAh·g^-1 (20 mA·g^-1), 69.6 mAh·g^-1 (100 mA·g^-1)和26.5 mAh·g^-1 (600mA·g^-1). 4.0%(w) RGO/TiO₂复合材料体现了良好的循环稳定性, 在100 mA·g^-1电流密度下充放电循环350个周期后, 比容量仍然保持146.7 mAh·g^-1. 同等条件下, 纯TiO₂电极比容量只有68.8 mAh·g^-1. RGO包覆改性极大提高了TiO₂在钠离子电池中的电化学嵌钠/脱钠性能. RGO包覆改性技术在改进钠离子电池材料性能中将有很好的应用前景.     

Octahedral Cuprous Oxide Decorated Flexible Reduced Graphene Oxide Paper for Food Sensing Application

This work presents a simple method to fabricate an octahedral cuprous oxide (Cu₂O) decorated two-dimensional (2D) flexible rGOP electrode with filtration and electrodeposition strategies. The characteristic of the Cu₂O/rGOP electrodes was recorded by SEM, EDX, XPS, XRD, and Raman spectroscopy. The results clearly showed that Cu₂O was successfully electrodeposited on the surface of rGOP by controlling the electrodeposition potential without the introduction of any template or surfactant. The electrochemical characterizations of the Cu₂O/rGOP exhibited high electrocatalytic activity toward the reduction of H₂O₂. The linear detection range for the Cu₂O/rGOP flexible sensor was 5.0 μM to 5.5 mM, with a limit of detection of 1.27 μΜ. Subsequently, the developed flexible rGOP sensor was extended for H₂O₂ detection in milk samples for avoiding milk spoilage_. Such judicial preparation of rGOP as a sensing device will certainly pave the way for various other sensing applications including environmental and biomedical applications.     

Electrochemical Detection of Alloxan on Reduced Graphene Oxide Modified Glassy Carbon Electrode

Alloxan is a toxic reagent that strongly induces the diabetes by destroying insulin‐producing β‐cells in the pancreas of living organisms. The reduction product of alloxan is dialuric acid, which is responsible for the intracellular generation of ROS to enhance the stress in living cells to cause kidney disease or diabetic nephropathy. Herein, we studied for the first time the electrochemical properties of alloxan on reduced graphene oxide modified glassy carbon electrode (rGO/GCE) in 0.1 M phosphate buffer solution (PBS) at pH 7. The obtained results were compared with graphene oxide modified GCE (GO/GCE) and bare GCE surfaces. The modified rGO/GCE showed well defined redox couple with 10 fold increase in both reduction as well as oxidation peak current for alloxan than that of GO/GCE and bare GCE. Differential pulse voltammetry (DPV) technique shows the linear increase in both oxidation and reduction peak current of alloxan in the range of 30 μM to 3 mM with LOD of 1.2 μM. An amperometric signal of alloxan is also increases with respect to each addition of 50 μM of alloxan on rGO/GCE at constant potential of ?0.05 V. The linear range of alloxan is observed between 50 μM to 750 μM (S/N=3). This kind of rGO/GCE surface is more suitable platform or sensor matrix for estimating unknown concentration of alloxan molecule in the real biological systems.     

尿酸在石墨烯修饰玻碳电极上的电化学行为及测定

以抗坏血酸为还原剂,采用微波水热法化学还原氧化石墨烯合成了石墨烯纳米片,制备了石墨烯修饰的玻碳电极(RGO/GCE),并采用循环伏安法、计时电量法、交流阻抗法等电化学技术研究了尿酸在该修饰电极上的电化学行为及其影响因素。结果表明,在PBS缓冲溶液中,尿酸(UA)在石墨烯修饰电极上的电极反应是一个受扩散控制的不可逆氧化过程。电极反应的转移电子数n=2,有效面积A=0.182 cm2,扩散系数D=1.51×10-6 cm2.s-1。UA的氧化峰电流与其浓度在5.0×10-6～1.5×10-4 mol/L范围内呈良好线性,r=0.995 7。利用该RGO/GCE修饰电极可以快速准确地测定UA,检出限为2.7×10-7 mol/L,加标回收率为98%～100%。     

Electrocatalytic Detection of Uric Acid on Nitrogen‐Doped Graphene Modified Electrode and Its Application

Nitrogen‐doped graphene (NG) was used to modify a glassy carbon electrode (GCE), which was applied to the voltammetric detection of uric acid (UA). Because of the presence of NG on the GCE surface, the modified electrode showed excellent electrocatalytic ability for UA oxidation with increase of the peak current and decrease of the peak potential. Compared to that of the traditional GCE, the overpotential of the oxidation peak decreased by 50 mV. Electrochemical performance of UA was studied on NG/GCE in detail, which showed a quasi‐reversible, diffusional‐controlled process. Electrochemical parameters including the charge transfer coefficient (α ), the number of electron transfer (n ), and the diffusional coefficient (D ) were calculated. At the optimal conditions, the oxidation peak current was linear, with UA concentration from 0.1 to 10.0 μmol/L as revealed by differential pulse voltammetry, and the detection limit was estimated as 0.042 μmol/L (3σ). The UA content in the urine sample of a healthy volunteer was determined by the proposed method with a recovery of 98.7–102.3%.     

Synthesis of Zinc Tetraaminophthalocyanine Functionalized Graphene Nanosheets as an Enhanced Material for Sensitive Electrochemical Determination of Uric Acid

A new electrochemical sensor material has been fabricated via the non‐covalent functionalization of reduced graphene oxide (rGO) and soluble tetramino zincphthalocyanines (ZnPc‐NH₂). Immobilization of uricase onto the synthesized nanohybrids can evidently improve the electrocatalytic activity and selectivity. The obtained composite membrane possesses a great enhancement of electron transfer rate and excellent synergistic electrocatalytic effect toward uric acid (UA) oxidation under the working potential at 0.620 V vs. Ag/AgCl with a scan rate of 0.125 V/s. The effects of the experimental parameters on the electrochemical oxidation responses of UA were investigated and optimized in detail. Under the optimized conditions, the peak currents were proportional to the UA concentration in a range from 0.5 to 100 μmol/L with detection limit of 0.15 μmol/L. Moreover, the developed sensor was applied for UA determination in human urine samples with high accuracy and satisfactory recovery, which is envisioned to have promising applications in monitoring UA in clinical research.     

Graphene Nanocomposites Based Electrochemical Sensing Platform for Simultaneous Detection of Multi-drugs

Three reduced graphene oxide nanocomposites were employed to achieve the simultaneous electrochemical determination of multi-drugs including acetaminophen (ACTM), carbendazim (CB) and ciprofloxacin (CFX). All nanocomposite modified electrodes showed improved current responses for three drugs. Notably cauliflower-like platinum nanoparticles decorated reduced graphene oxide modified electrode (or Pt−RGO/GCE) exhibited the best performance in terms of electrochemical stability. Using Pt−RGO/GCE, the linear detect ranges of 30–120 μM, 25–115 μM and 10–25 μM, and detection limit values of 3.49, 2.96, and 1.53 μM were achieved for ACTM, CB and CFX respectively. The electrode was further used for the successful determination of above drugs in tap and river water using differential pulse voltammetry. From the obtained results, we believe that Pt-RGO/GCE is highly promising for the fabrication of robust electrochemical sensors for simultaneously determining ACTM, CB and CFX or similar types of drugs in the future.     

壳聚糖/氮掺杂还原氧化石墨烯修饰电极对黄嘌呤的检测及尿酸抑制的研究

用碳热还原法制备氮掺杂还原氧化石墨烯(N-RGO),用壳聚糖(CS)的乙酸溶液作为氮掺杂还原氧化石墨烯(N-RGO)的分散剂,将其修饰在玻碳电极表面,用于检测黄嘌呤(xanthine).该传感器对黄嘌呤展现出优异的电化学响应,线性范围为2.99×10^-8～1.07×10^-4mol/L,检测限为9.96×10^-9mol/L(S/N=3).此外,利用循环伏安法(CV)对黄嘌呤电化学行为进行了研究.最后,用电化学的方法研究了非布索坦(Febuxostat)和别嘌呤醇(Allopurinol)两种药物对尿酸生成的抑制.本工作为痛风的诊断和治疗提供了重要的信息.     

用于压力传感的还原氧化石墨烯/丝蛋白基多孔复合材料

利用丝蛋白能够在还原氧化石墨烯片层上发生选择性聚集的特性,制备了还原氧化石墨烯片层上富集有丝蛋白微纤且分散性良好的还原氧化石墨烯片和丝蛋白混合溶液,并通过冷冻以及低温乙醇处理的方法得到一系列不同比例的还原氧化石墨烯/丝蛋白基多孔复合材料.随后,采用溶液浸泡的方法在多孔材料表面再次沉积还原氧化石墨烯,以进一步提高还原氧化石墨烯/丝蛋白基多孔复合材料的压敏导电性.系统观察和测试结果表明,还原氧化石墨烯的引入,不仅使得多孔材料内部出现了相应的微纳结构,同时也提高了多孔材料的力学性能.还原氧化石墨烯/丝蛋白基多孔复合材料在完全湿态下兼具较好的强度和弹性,可以在0%~80%的压缩应变之间实现良好的压缩回复效果和压力传感性能.其中,最佳比例下的还原氧化石墨烯/丝蛋白基多孔复合材料在低压力下的灵敏度可达0.15 kPa?1,在0~17.3 kPa范围内能够高效工作并且具有优异的电学稳定性和耐疲劳性.因此,还原氧化石墨烯/丝蛋白基多孔复合材料因其高灵敏度、宽工作范围、结构可调以及可塑性好等诸多优点,有望在柔性压力传感方面获得较好的应用.     

Electrochemical Sensor for Sensitive Determination of Capsaicin Using Pd Decorated Reduced Graphene Oxide

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.     

Selective Voltammetric Detection of Uric Acid in the Presence of Ascorbic Acid at Well‐Aligned Carbon Nanotube Electrode

The voltammetric behaviors of uric acid (UA) and L ‐ascorbic acid (L ‐AA) were studied at well‐aligned carbon nanotube electrode. Compared to glassy carbon, carbon nanotube electrode catalyzes oxidation of UA and L ‐AA, reducing the overpotentials by about 0.028 V and 0.416 V, respectively. Based on its differential catalytic function toward the oxidation of UA and L ‐AA, the carbon nanotube electrode resolved the overlapping voltammetric response of UA and L ‐AA into two well‐defined voltammetric peaks in applying both cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which can be used for a selective determination of UA in the presence of L ‐AA. The peak current obtained from DPV was linearly dependent on the UA concentration in the range of 0.2 μM to 80 μM with a correlation coefficient of 0.997. The detection limit (3δ) for UA was found to be 0.1 μM. Finally, the carbon nanotube electrode was successfully demonstrated as a electrochemical sensor to the determination of UA in human urine samples by simple dilution without further pretreatment.     

聚吡咯/氧化石墨烯层状复合材料的制备及其在超级电容器中的应用(英文)

通过将吡咯单体在低温下与氧化石墨烯进行原位聚合,获得聚吡咯/石墨烯(Ppy/CRGO)复合材料.采用场发射电子显微镜(FESEM)、红外(FT-IR)和热重分析(TGA)对复合物的表面形貌、结构进行表征.FESEM结果表明,通过控制氧化石墨烯(GO)和吡咯单体的质量比例,可以对复合物的层状和厚度进行调控.FT-IR和TGA结果表明,聚吡咯(Ppy)是通过化学键合的方式与氧化石墨烯复合在一起.通过机械冷压法将粉末状Ppy/CRGO复合物压成圆片电极,并探讨了石墨烯和聚吡咯复合比例、反应时间、烘干温度和孔隙率等因素对Ppy/CRGO复合物电极的电学和电化学性能的影响.结果表明,Ppy与CRGO质量比为10∶1所制得的Ppy/CRGO复合物的电容量为421 F·g-1,通过在电极中引入孔隙,电容量能进一步提升为509 F·g-1.     

二氧化锆/石墨烯复合材料对亚硝酸盐的电化学传感研究

制备了一种二氧化锆/还原氧化石墨烯(ZrO2NPs/rGO)复合材料修饰电极的亚硝酸盐电化学传感器,并成功用于亚硝酸盐的检测.采用循环伏安法和电流-时间曲线考察了修饰电极的电化学行为.实验结果表明,ZrO2NPs/rGO复合材料修饰电极对亚硝酸盐具有良好的电流响应.在最优实验条件下,电流-时间曲线中的电流响应信号与亚硝酸盐浓度在3.0×10Symbolm@@_7～1.0×10Symbolm@@_6 mol/L和1.0×10Symbolm@@_6～6.0×10Symbolm@@_6 mol/L的范围内呈良好的线性关系,检测限为1.0×10Symbolm@@_7 mol/L(S/N 3).该传感器灵敏性高、稳定性和重现性好.使用此传感器检测实际样品香肠中的亚硝酸盐的回收率为93.7％～110.4％,相对标准偏差为1.6％～2.1％.     

DNA Induced FePt Bimetallic Nanoparticles on Reduced Graphene Oxide for Electrochemical Determination of Dopamine

FePt bimetallic nanoparticles were formed on reduced graphene oxide(rGO) with the help of double-stranded DNA(dsDNA) via a simple and universal route to obtain a FePt/DNA-rGO composite. The FePt nanoparticles with an average size of about 5 nm were well dispersed on rGO. FePt/DNA-rGO modified glassy carbon electrode(GCE) exhibited excellent electrocatalytic activity for the oxidation of dopamine(DA) with a detection limit of 100 nmol/L(S/N = 3). In addition, the FePt/DNA-rGO based electrochemical sensor showed an excellent selectivity for DA in the presence of ascorbic acid(AA), uric acid(UA) and other interference reagents. The as-prepared electrochemical biosensor shows great promise in the application of clinical diagnostics.     

Electrochemical Fabrication of Prussian Blue Nanocube‐decorated Electroreduced Graphene Oxide for Amperometric Sensing of NADH

In this study, Prussian blue (PB) film on the electroreduced graphene oxide (ERGO)‐modified Au electrode surface (ERGO/PB) is easily prepared by means of cyclic voltammetric technique in the mixture of K₃Fe(CN)₆ and FeCl₃. Its electrochemical behaviors for NADH biosensor are studied. The structural and morphological characters of modified electrode material are analyzed with using of XPS, XRD, Raman, EDS, and SEM techniques. ERGO/PB hybrid nanocomposite for NADH biosensor is exhibited to the higher catalytic effect (linear range from 1.0 to 100 μM, detection limit of 0.23 μM at S/N=3) compared to naked Au, ERGO‐modified Au, and PB‐modified Au electrodes. In addition to, ERGO/PB electrode was used to voltammetric and amperometric detection of H₂O₂. ERGO/PB electrodes also showed the same behavior as the NADH sensor. This ERGO/PB‐modified electrode supplied a simple, new, and low‐cost route for amperometric sensing of both NADH and H₂O₂.     

Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid,at a Graphene Paste Electrode Modified with Functionalized Graphene Sheets

The present study reports the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in phosphate buffer solution (pH 7.0) using graphene paste electrode modified with functionalized graphene sheets (GPE‐MFGSs). The presence of FGS inhibited the adsorption of AA owing to the electrostatic repulsion, but was favorable for the affinity adsorption of DA and UA via the ion exchange and hydrogen bonding mechanisms, respectively. This led to the decrease in the oxidation potential of AA and the significantly enhanced oxidation peak currents of DA and UA at the GPE‐MFGSs. By cyclic voltammetry and differential pulse voltammetry, the oxidation potentials of AA, DA, and UA, at the GPE‐MFGSs in a ternary mixture were found to be well resolved so that their simultaneous determination could be achieved. Furthermore, the influence of some experimental variables such as graphene paste composition, working solution pH, scan rate and pulse amplitude was studied. In addition, by differential pulse voltammetry, the linear dependence of peak current on the concentration was obtained in the ranges of 0.05–9.0, 0.03–13, and 0.03–5.5 µM with the lowest detection limits of 0.02, 0.01, and 0.01 µM for AA, DAand UA, , respectively.     

基于过渡金属硫化物/还原氧化石墨烯复合物的高性能超级电容器

组装高能量密度的非对称超级电容器需要使用比电容大、 体积变化小且循环稳定性好的电极材料. 过渡金属硫化物(TMSs)与纳米碳材料的复合物是此类电极材料之一. 采用水热法合成了由Cu-Mo硫化物在微波剥离的还原氧化石墨烯表面生长的复合材料(CuS-MoS₂/MErGO). 此复合材料在电流密度为2 A/g时具有高达861.5 F/g的比电容和良好的循环稳定性. 将1.6 V的电池电压施加在由NiS/MErGO为正极, CuS-MoS₂/MErGO为负极组装成的不对称超级电容器上时, 该电容器的功率密度为1.28 kW/kg, 且能量密度保持为54.2 W·h·kg^-1. 结果表明, TMS复合材料是一种很有前途的高性能电化学储能材料, 尤其是用于非对称超级电容器的组装.     

Graphene Doped Molecularly Imprinted Electrochemical Sensor for Uric Acid

A highly sensitive uric acid molecularly imprinted electrochemical sensor was prepared by using graphene doped chitosan as the functional matrix and uric acid as the template molecule; a electrodeposition technique was used to form a controllable graphene–chitosan–uric acid composited film on glassy carbon electrode whose uric acid was removed via electrochemical induce elution. Under the optimized preparation and detection conditions, the detection sensitivity of uric acid at graphene doped molecularly imprinted sensor was improved significantly compared with the undoped molecularly imprinted sensor. The mechanisms of sensitivity enhancement were studied by a.c. electrochemical impedance, adsorption model, and chronocoulometry. The observations suggest the effect of sensitivity enhancement resulted from magnified surface area and good electronic conduction of graphene. Additionally, the developed sensor exhibited specific recognition to uric acid against the competitors which consisted of structure liked substances and coexisting interference in blood serum.     

Manganese Oxide Nanoparticles/Reduced Graphene Oxide as Novel Electrochemical Platform for Immobilization of FAD and its Application as Highly Sensitive Persulfate Sensor

In this study, manganese oxide nanoparticles/reduced graphene oxide(MnOxNPs/rGO) was used as support for strong immobilization of flavin adenine dinucleotide(FAD). A thin film of rGO cast on the electrode surface, followed by performing electrodeposition of MnOxNPs at applied constant potential of +1.4 V vs. Ag/AgCl for 200 s. Finally, FAD was electrodeposited onto the rGO/MnOxNPs film by potential cycling between 1.0 to ?1.0 V in solution containing 1 mg ml^?1 FAD. Electrochemical properties and catalytic activity of GCE/rGO‐MnOxNPs/FAD toward persulfate (S₂O₈^2?) reduction was investigated. Under optimized condition, the concentration calibration range, detection limit, and sensitivity were 0.1 μM–2 mM, 90 nM and 125.8 nA/μM, respectively, using hydrodynamic amperometry technique.     

Prussian Blue Nanoparticles Self Assembling on Electrochemically Reduced Graphene Oxide Modified GC Electrode for Sensitive Hydrogen Peroxide Detection

A facile, fast, and convenient route was suggested for the fabrication of Prussian blue nano particles (PBNPs) assembled on reduced graphene oxide (RGO) modified glassy carbon electrode (PBNPs|RGO|GCE). RGO was electrodeposited on the surface of GCE and the prepared RGO|GCE was immersed into a ferric‐hexacyanoferrate(III) solution and PBNPs were assembled on the RGO|GCE for a certain period of time. The PBNPs film thickness can be easily controlled by adjusting the assembling duration. The developed PBNPs|RGO|GCE was successfully used for determining hydrogen peroxide, with a linear response over the concentration range 0.5‐400 μM, a good accuracy and precision, detection limit 0.44 μM, and sensitivity 1168 mA M^?1 cm^?2.