MnO2/Graphene Nanocomposites for Nonenzymatic Electrochemical Detection of Hydrogen Peroxide

MnO₂/graphene nanocomposites with different morphologies were synthesized and the petal‐shaped nanosheet MnO₂/graphene composite was developed as an electrode material for nonenzymatic hydrogen peroxide (H₂O₂) sensor. The morphology, structure, composition, and hydrophilicity of the resulting products were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and the contact angle tests. In addition, the fabricated MnO₂/graphene composites could be used as catalysts for the electrochemical oxidation of H₂O₂. Cyclic voltammogram (CV) experiments indicated that MnO₂/graphene‐modified electrode showed good electrocatalytic activity towards both the oxidation and reduction of H₂O₂ in a neutral environment. Amperometric response results illustrated that this nonenzymatic sensor had excellent anti‐interference ability and displayed two linear ranges from 10 to 90 µM and from 0.2 to 0.9 mM with a detection limit of 2 µM.     

Prussian Blue Modified Submicron Structured Gold Electrodes for Amperometric Hydrogen Peroxide Sensing

In this work, we present a simple and effective approach for fabricating sub‐micron structured gold (SM−Au) electrodes by chemically etching the magnetron co‐sputtered gold film in KI solution for certain time. Such electrodes with a large surface area to volume ratio were used as the matrix for electrochemical deposition of Prussian blue (PB) to develop an electrochemical hydrogen peroxide sensor. Experimental characterization using scanning electron microscope and atomic force microscope shows that the thickness of PB layer on SM−Au electrode is around 140 nm, and is composited with cubic PB nanocrystals. The electrochemical performance of the designed sensor, studied using cyclic voltammograms and chronoamperometry methods, suggests that the sensor based on SM−Au/PB electrode presents the direct electron transfer of PB particle towards SM−Au film, and exhibits fast response, wide linearity, low detection limit and high stability. Under the optimized conditions, the sensitivity of the developed sensor for the detection of H₂O₂ reaches the value of 512 mA cm⁻² M⁻¹ with a linear range from 1 μM to 4.5 mM.     

Enzyme‐free Cu2O@MnO2/GCE for Hydrogen Peroxide Sensing

A novel composite material of copper (I) oxide at manganese (IV) oxide (Cu₂O@MnO₂), was synthesized and applied for modification on the glassy carbon electrode (GCE) surface (Cu₂O@MnO₂/GCE) as a hydrogen peroxide (H₂O₂) sensor. The composite material was characterized regarding its structural and morphological properties, using field emission scanning electron microscopy (FE‐SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The Cu₂O@MnO₂/GCE showed an excellent electrocatalytic response to the oxidation of H₂O₂ which provided a 0.56 s^?1 charge transfer rate constant (K_s), 1.65×10^?5 cm² s^?1 diffusion coefficient value (D), 0.12 mm² electroactive surface area (A_e) and 1.04×10^?8 mol cm^?2 surface concentration ( ). At the optimal condition, the constructed sensor exhibited a wide linear range from 0.5 μM to 20 mM with a low limit of detection (63 nM, (S/N=3) and a good sensitivity of 256.33 μA mM^?1 cm^?2. It also presented high stability (ΔI_response±15 %, n=100), repeatability (1.25 %RSD, n=10) and reproducibility (3.55 %RSD, n=10). The results indicated that the synthesized Cu₂O@MnO₂ was successfully used as a new platform for H₂O₂ sensing.     

Synthesis of Ferrocene Based Naphthoquinones and its Application as Novel Non‐enzymatic Hydrogen Peroxide

At present, a highly sensitive hydrogen peroxide (H₂O₂) sensor is fabricated by ferrocene based naphthaquinone derivatives as 2,3‐Diferrocenyl‐1,4‐naphthoquinone and 2‐bromo‐3‐ferrocenyl‐1,4‐naphthoquinone. These ferrocene based naphthaquinone derivatives are characterized by H‐NMR and C‐NMR. The electrochemical properties of these ferrocene based naphthaquinone are investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) on modified glassy carbon electrode (GCE). The modified electrode with ferrocene based naphthaquinone derivatives exhibits an improved voltammetric response to the H₂O₂ redox reaction. 2‐bromo‐3‐ferrocenyl‐1,4‐naphthoquinone show excellent non‐enzymatic sensing ability towards H₂O₂ response with a detection limitation of 2.7 μmol/L a wide detection range from 10 μM to 400 μM in H₂O₂ detection. The sensor also exhibits short response time (1 s) and good sensitivity of 71.4 μA mM^?1 cm^?2 and stability. Furthermore, the DPV method exhibited very high sensitivity (18999 μA mM^?1 cm^?2) and low detection limit (0.66 μM) compared to the CA method. Ferrocene based naphthaquinone derivative based sensors have a lower cost and high stability. Thus, this novel non‐enzyme sensor has potential application in H₂O₂ detection.     

Novel Nonenzymatic Hydrogen Peroxide Sensor Based on Ag/Cu2O Nanocomposites

The nanocomposites of Ag nanoparticles supported on Cu₂O were prepared and used for fabricating a novel nonenzymatic H₂O₂ sensor. The morphology and composition of the nanocomposites were characterized using the scanning electron microscope (SEM), transmission electron microscope (TEM), energy‐dispersive X‐ray spectrum (EDX) and X‐ray diffraction spectrum (XRD). The electrochemical investigations indicate that the sensor possesses an excellent performance toward H₂O₂. The linear range is estimated to be from 2.0 μM to 13.0 mM with a sensitivity of 88.9 μA mM^?1 cm^?2, a response time of 3 s and a low detection limit of 0.7 μM at a signal‐to‐noise ratio of 3. Additionally, the sensor exhibits good anti‐interference.     

Flexible Glass‐based Amperometric Sensors for Hydrogen Peroxide

The development of flexible sensors could enable significant advances in clinical diagnosis, defense, and environmental monitoring. Flexible glass provides the flexibility and possesses stable chemical and physical properties. Here, we show that carbon graphite and silver/silver chloride inks can be printed onto flexible glass to construct amperometric sensors, and the sensors show sensitive and rapid detections of hydrogen peroxide. We anticipate that these results could provide exciting avenues for fundamental studies of flexible electronics and flexible bioelectronics, as well as a variety of applications in fields ranging from medical diagnosis to defense.     

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.     

Cuprous Oxide/Nitrogen-doped Graphene Nanocomposites as Electrochemical Sensors for Ofloxacin Determination

Cu₂O/nitrogen-doped grapheme(NG) nanocomposite material was prepared via a facile one step chemical reduction and characterized by means of X-ray diffraction(XRD) and scanning electron microscopy(SEM). A new electrochemical sensor was then fabricated by coating Cu₂O/nitrogen-doped graphene nanocomposite with Nafion on glassy carbon electrode(Cu₂O/NG/Nafion/GCE). The electrochemical response of this modified electrode toward ofloxacin was examined by cyclic voltammetry. The results indicate that Cu₂O/NG/Nafion composite-modified electrode exhibits higher catalytic activity in the electrochemical oxidation of ofloxacin compared with glassy carbon electrode(GCE), Cu₂O/Nafion modified electrode(Cu₂O/Nafion/GCE), and N-doped graphene/Nafion modified electrode(NG/Nafion/GCE). Under optimal conditions, the peak current was found to be linearly proportional to the concentration of ofloxacin in the 0.5-27.5 μmol/L and 27.5-280 μmol/L ranges with a lower detection limit of 0.34 μmol/L, higher sensitivity of 39.32 μA·L·mmol^-1 and a shorter reaction time of less than 2 s. In addition, Nafion can enhance the stability of the modified electrode and prevent some negative species. Thus the modified electrode exhibits good selectivity and a long working life. The Cu₂O/NG/Nafion composite modified electrode shows promising application in electrochemical sensors, biosensors, and other related fields because of its excellent properties.     

Sensitive Nonenzymatic Electrochemiluminescence Determination of Hydrogen Peroxide in Dental Products using a Polypyrrole/Polyluminol/Titanium Dioxide Nanocomposite

A layer-by-layer assembled of a polypyrrole and polyluminol was synthesized through the electrodeposition of pyrrole and luminol in acidic medium on a graphite electrode. The electrode was then modified by casting titanium dioxide (TiO₂) nanoparticles on its surface for enhancing electrochemiluminescence of luminol. The properties of this electrochemiluminescence sensor were studied by cyclic voltammetry, electrochemical impedance spectroscopy, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results demonstrated that the modification of this electrochemiluminescence sensor shows sensitive response for the determination of hydrogen peroxide. Figures of merit include broad linearity from 1?pmol L^?1 to 4?µmol L^?1 (R²?=?0.996) with a limit of detection as low as 0.40?pmol L^?1 at a signal-to-noise ratio of three and good reproducibility with relative standard deviation of 4% for the determination of a 400?nmol L^?1 hydrogen peroxide solution (n?=?4), along with favorable long-term stability. The presence of glucose, citric acid, uric acid, dopamine, and ascorbic acid at concentrations as high as 100?nmol L^?1 of H₂O₂ did not produce any electrochemiluminescence signals, which demonstrates the selective nature of this modified electrode. The sensor was also used for the determination of H₂O₂ in mouthwash formulations and dental whitelight gels.     

CuO Crystalline Modified Glassy Carbon Electrodes for Anodic Amperometric Determination of Hydrogen Peroxide

As an alternative selection of electrocatalytic surface modifier, the electrochemically generated copper oxides is re‐ investigated by using cyclic voltammetry (CV), scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS). Interesting phenomena have been found, which indicate that the electrodeposition from the Cu²⁺ solution under cyclic voltammetric conditions can generate a transparent Cu(OH)₂ crystalline on the surface of glassy carbon electrodes, and this crystalline can be further transferred to a novel cubic opaque CuO crystalline of about 300 nm in size by second step of cyclic voltammetry in pH 12 NaOH solution. The final electrode (denoted as nano‐CuO/GCE) can catalyze the oxidation (as well as the reduction) of H₂O₂ in basic solutions. It shows pH dependent three‐part catalytic mechanism in the range from pH 7 to pH 14. In 0.10 mol/L NaOH solution, the amperometric response at 0.15 V (vs. SCE) can give a current sensitivity as high as 139 mA/(mol·L^?1) in the rage of 5.0×10^?7?6.0×10^?4 mol/L with a lower detection limit (s/n=3) of 2.5×10^?8 mol/L, and a current sensitivity of 78.4 mA/(mol·L^?1) in the rage of 6.0×10^?4–2.0×10^?3 mol/L. This electrode also has excellent reproducibility and stability. The mechanisms for the two steps of preparation and the catalytic reactions are proposed. The nano‐CuO crystalline modified electrode may have more applications in the field of electrochemical sensing.     

Heterostructural NiCo2O4 Nanocomposites for Nonenzymatic Electrochemical Glucose Sensing

Hierarchical nanocomposites consisting of NiCo₂O₄ nanorods and NiCo₂O₄ nanoparticles through a straightforward two-step hydrothermal process was employed as a working electrode to examine the electrochemical behavior of glucose. The NiCo₂O₄@NiCo₂O₄ heterostructures was confirmed by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffractometer (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemistry analysis. Results indicated that glucose is electrochemically oxidized with improved sensitivity at the NiCo₂O₄@NiCo₂O₄ sensor, compared to NiCo₂O₄ sensors. Analytical parameters such as the optimal potential (0.45 V), linear range from 0.4 μM to 5.2 mM, limit of detection (1.1 μΜ) (S/N=3), stability and repeatability (2.7 %) demonstrate the suitability of the prepared sensor for glucose analysis. Moreover, the proposed sensor could be used for actual samples analysis in complex matrices.     

Amperometric Detection of Hydrogen Peroxide Using Glassy Carbon Electrodes Modified with Chromium Hexacyanoferrate/Single‐Walled Carbon Nanotube Nanocomposites

Chemical functionalization of single‐walled carbon nanotubes (SWNTs) has constructed plenty of new structures with useful properties. But the modification was often confined to organic molecules, either by covalence or noncovalence. In this report, SWNTs were successfully functionalized with one kind of electroactive inorganic compounds: chromium hexacyanoferrate (Cr hcf). The resulting Cr hcf/SWNTs nanocomposites were confirmed by Field‐emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), UV‐vis absorption spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Cr hcf crystallites are observed to be finely attached to the SWNTs. The electrochemical properties of Cr hcf/SWNTs nanocomposites were also investigated. The nanocomposites modified glassy carbon (GC) electrode shows high electrocatalytic activity towards the reduction of H₂O₂ and the amperometric responses show a linear dependence on the concentration of H₂O₂ in a range of 0.5 μM to 10 mM (R=0.9989). In addition, the sensor has good stability and reproducibility.     

以N—甲基吩嗪硫酸盐为电子传递体的过氧化氢传感器

用再生丝素把过氧化物酶（ＰＯＤ）固定在玻碳电极表面，以Ｎ－甲基吩嗪硫酸盐（ＰＭＳ）为电子传递体，制成过氧化氢传感器，因该酸电极对过氧化氢（Ｈ２Ｏ２）有良好的催化响应，ＰＭＳ还原电流的增值与过氧化氢的浓度在１０＾－６－１０＾－３ｍｏｌ／Ｌ范围内有良好的线性关系，酶电极稳定性好，灵敏度高，对过氧化氢的响应时间小于１０ｓ，其有效寿命可达二个月以上。用扫描电镜和红外光谱观察和分析了ＰＯＤ和再生丝素共混膜的     

Gold Nanoparticles-electrochemically Reduced Graphene Oxide/Poly(indole-5-carboxylic acid) Nanocomposite for Electrochemical Non-enzymatic Sensing of Hydrogen Peroxide

Herein, co-electrodeposition of AuNPs and ERGO onto GCE was conducted to prepare the modified electrode, GCE/AuNPs-ERGO. The poly(indole-5-carboxylic acid) (P(In-5-COOH) was then coated onto the GCE/AuNPs-ERGO with the help of electropolymerization. FT-IR, FE-SEM and EDX, and XRD techniques were employed to characterize the prepared nanocomposite. The nanocomposite modified electrode (GCE/AuNPs-ERGO/P(In-5-COOH)) was examined for the electrochemical reduction of H₂O₂ using chronoamperometry. A high reduction current for H₂O₂ was observed due to the synergistic effect between AuNPs-ERGO and P(In-5-COOH). The proposed sensor demonstrated a wide linear range of 0.025–750 μmol L⁻¹, with a LOD of 0.008 μmol L⁻¹ at −0.4 V. Furthermore, the developed sensor was applied for the detection of H₂O₂ in fetal bovine serum and urine samples.     

Amperometric Biosensor for Hydrogen Peroxide Based on Electrodeposited Sub-micrometer Gold Modified Glassy Carbon Electrode

IntroductionAmperometricbiosensorofhydrogenperoxideisofpracticalimportancebecauseofitswideapplicationsinchemical,biological,clinical,environmentalandmanyotherfields.Forimprovementofsensor抯quality,vari-ouskindsofchemicalmodificationmethodshavebeendevelopedforreducingredoxoverpotentialsofH2O2atelectrodesurfaces,increasingthedetectionsensitivity,linearrange,stabilityandlivetime.Ithasbeenshownthattheuseofsub-micrometersizedmetalparticlessuchasPt-blackcansignificantlyimprovethequalityofthebiosens…     

Extremely Stable Copper–Polymelamine Composite Material for Amperometric Hydrogen Peroxide Sensing

For the first time, electroactive poly(melamine) film has been prepared and evaluated to function as a matrix to immobilize “spherical” copper nanoclusters and also as a ligand to form a copper complex with enhanced electrocatalytic activity. This is a simple two‐step process that involves first polymerization of melamine on a screen‐printed carbon electrode followed by electrodeposition of copper without using harmful and environmentally toxic chemicals. It is remarkable that this electrode can electrocatalytically reduce H₂O₂ at approximately ?0.2 V versus Ag/AgCl in pH 7 PBS and possesses superior stability in amperometric analysis of H₂O₂ under the continuous wall‐jet flow of 1 mM of H₂O₂ for more than 5 h. Most importantly, we have demonstrated that the as‐prepared copper‐poly(melamine)‐modified electrode can solve the setbacks of copper‐based H₂O₂ sensors reported so far. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1639–1646     

CO/H2O/O2直接法制过氧化氢的环境友好纳米Cu/Al2O3催化剂

采用液相化学还原法制备了系列用于一氧化碳、水及氧气直接法制过氧化氢的环境友好纳米Cu/Al2O3催化剂,并用TEM,XRD和N2O化学滴定等手段对催化剂中纳米金属铜的结构及性质进行了表征.研究结果表明,Cu/Al2O3催化剂在CO/H2O/O2直接法制H2O2反应中呈现出显著的纳米尺寸效应当金属铜纳米晶粒平均尺寸为15 nm时,有高达0.236 mmol·(g-cat)-1·h-1的H2O2生成速率.     

Dendrimer Templated Synthesis of Carbon Nanotube Supported PdAu Catalyst and its Application as Hydrogen Peroxide Sensor

At present, CNT supported catalysts were prepared by two different methods as NaBH₄ reduction and dendrimer templated NaBH₄ reduction method to observe the effect of preparation method on the sensitivity and activity of H₂O₂ reduction. Then, CNT supported Pd_xAu_y bimetallic nanocatalysts having various atomic ratio were synthesized via novel dendrimer templated NaBH₄ reduction method. The resulting materials were characterized employing XRD and TEM. Crystallite size of 10 %Pd_0.7Au_0.3/CNT_dendrimer was obtained from XRD 17.1 nm and mean particle size obtained from TEM is about 15 nm. Moreover, the electrochemical behavior of these catalysts was characterized by cyclic voltammetry (CV) and chronoamperometry (CA) techniques. Pd_xAu_y bimetallic nanocatalysts have excellent electrocatalytic properties and great potential for applications in electrochemical detection. The sensitivity and the limit of detection values for the prepared sensor with monometallic 10 % Pd/CNT_dendrimer catalysts are 219.78 μA mM^?1cm^?2 and 2.6 μM, respectively. However, the sensor constructed with 10 %Pd_0.7Au_0.3/CNT_dendrimer modified electrode has a very high sensitivity of 316.89 μA mM^?1 cm^?2 with a quick response time of 2 s and a wide linear range of 0.001–19.0 mM. In addition, the interference experiment indicated that the 10 % Pd_0.7Au_0.3/CNT_dendrimer nanoparticles have good selectivity toward H₂O₂.