Electrochemical Detection Of H2O2 Research Articles

Co-embedded N-doped hierarchical carbon arrays with boosting electrocatalytic activity for in situ electrochemical detection of H2O2

In this work, self-supporting hierarchical Co-embedded N-doped carbon structures composed of leaf-like carbon sheets arrays and interconnected carbon nanotubes (CNTs) were synthesized on carbon cloth (CC) via dicyandiamide-assisted pyrolysis. The resultant composite is abbreviated as CC/Co@C-CNTs, in which Co nanoparticles are embedded both in carbon sheets and the tips of CNTs. The characterizations proved the hierarchical three-dimensional structure, large electroactive surface area of 4.71 cm−2, fast electron transfer, abundant Co/Co-Nx active sites, and synergistic effect between Co/Co-Nx species and CNTs in the CC/Co@C-CNTs-800-0.10 electrocatalyst. Benefiting from these unique superiorities, the CC/Co@C-CNTs-800-0.10 freestanding electrode exhibits excellent sensing performances of H2O2. It possesses a high sensitivity (388 μA mM-1 cm−2), fast response within 4 s, low detection limit (0.27 μM, S/N = 3) and wide linear range (0.40 μM–7.2 mM). More importantly, the freestanding electrode can be used to in situ detect H2O2 released from MDA-MB-231 cells and HeLa cells. This work provides a new design of nonenzymatic electrochemical sensing platform for amperometric determination of H2O2 in biological environment, which has great potential in cancer diagnosis, environmental monitoring and food analysis.

Iron sulfide nanosheets supported 3D foam: A binder-free electrocatalyst for sensitive and selective electrochemical H2O2 detection

Electrochemical nonenzymatic sensor has achieved numerous attentions from analytical chemistry communities. A facile and direct synthesis route for developing high-performance electrocatalyst is essential to improve efficiency of sensor in terms of cost and catalytic activities for reliable analysis applications. In this research, we introduced an easy synthesis approach for the in-situ fabrication of iron sulfide nanosheets (Fe–S NSs) vertically grown on a nickel foam (NF) via an electrodeposition step. Such a self-supported Fe–S NSs/NF demonstrated sensitive and selective determination towards hydrogen peroxide (H2O2) with a wide sensing region ranging from 10 μM to 3.3 mM in 0.1 M KOH medium. Besides, it’s excellent sensitivity of 4.48 μA μM−1 cm−2, low detection limit of 7.9 μM, good reproducibility, and stability have been successfully demonstrated as well. The facile fabrication process of Fe–S NSs/NF opened a novel and effective avenue for the development of non-precious metal-based electrocatalysts in analytical chemistry.

Prussian Blue Nanocubes‐SnO2 Quantum Dots‐Reduced Graphene Oxide Ternary Nanocomposite: An Efficient Non‐noble‐metal Electrocatalyst for Non‐enzymatic Detection of H2O2

AbstractDeveloping non‐noble‐metal electrocatalyst for non‐enzymatic H2O2 sensing is highly attractive. A facile, two‐step approach has been utilized for the synthesis of PBNCs/SnO2 QDs/RGO ternary nanocomposite. TEM, SEM, XPS, and XRD techniques were used to the characterize the structural and morphological properties of synthesized ternary nanocomposite. The synthesized ternary nanocomposite has been examined as an electrode material for the electrochemical detection of H2O2 using the Amperometry technique. Under optimum conditions, PBNCs/SnO2 QDs/RGO ternary nanocomposite performed very well in the electrocatalytic reduction of H2O2 with a linear dynamic range from 25–225 μM (R2=0.996) with a low detection limit of 71 nM (S/N=3). Compared to the recent literature, PBNCs/SnO2QDs/RGO ternary nanocomposite based modified electrode exhibit a wider linear dynamic range with a low detection limit. Furthermore, PBNCs/SnO2 QDs/RGO ternary nanocomposite based modified electrode showed an excellent anti‐interference ability against various common interfering agents. The practical applicability of this ternary nanocomposite based modified electrode was further extended to determine the H2O2 in tap water with acceptable recovery. The present performance of PBNCs/SnO2 QDs/RGO ternary nanocomposite material towards H2O2 sensing might widen its application for developing a new type of non‐noble metal‐based non‐enzymatic electrochemical biosensors.

Electrodeposition of pore-confined cobalt in metal–organic framework thin films toward electrochemical H2O2 detection

In this study, cobalt is electrodeposited within solvothermally grown thin films of a zirconium-based metal–organic framework, MOF-808, to obtain electrochemically active cobalt confined in the pore of MOF-808 crystals. With the help of the highly porous but electrically insulating MOF-808 thin film and a step-wise electrodepositing technique, cobalt can be mainly deposited within the pore of MOF-808 crystals. The resulting Co@MOF-808 thin film is applied for electrochemical H2O2 sensor in aqueous electrolytes, and its electrocatalytic activity toward H2O2 significantly outperforms that of the electrodeposited cobalt on a bare substrate. The electrochemical behavior of Co@MOF-808 thin films and the corresponding electrocatalytic mechanism toward H2O2 are investigated. The material is further used for amperometric H2O2 detection, and a sensitivity, limit of detection, and linear range of 382.27 μA/mM-cm2, 1.3 μM, and 10–450 μM can be achieved, respectively.

Novel Platinum-Porphyrin as Sensing Compound for Efficient Fluorescent and Electrochemical Detection of H2O2

Metalloporphyrins are highly recognized for their capacity to act as sensitive substances used in formulation of optical, fluorescent, and electrochemical sensors. A novel compound, namely Pt(II)-5,10,15,20-tetra-(4-allyloxy-phenyl) porphyrin, was synthesized by metalation with PtCl2(PhCN)2 of the corresponding porphyrin base and was fully characterized by UV-vis, fluorimetry, FT-IR, 1H-NMR, and 13C-NMR methods. The fluorescence response of this Pt-porphyrin in the presence of different concentrations of hydrogen peroxide was investigated. Besides, modified glassy carbon electrodes with this Pt-porphyrin (Pt-Porf-GCE) were realized and several electrochemical characterizations were comparatively performed with bare glassy carbon electrodes (GCE), in the absence or presence of hydrogen peroxide. The Pt-porphyrin demonstrated to be a successful sensitive material for the detection of hydrogen peroxide both by fluorimetric method in a concentration range relevant for biological samples (1.05–3.9 × 10−7 M) and by electrochemical method, in a larger concentration range from 1 × 10−6 M to 5 × 10−5 M. Based on different methods, this Pt-porphyrin can cover detection in diverse fields, from medical tests to food and agricultural monitoring, proving high accuracy (correlation coefficients over 99%) in both fluorimetric and electrochemical measurements.

Nanoporous carbon-fiber microelectrodes for sensitive detection of H2O2 and dopamine

In this study, sensitive electrochemical detection of H2O2 and dopamine (DA) was demonstrated using a nanoporous carbon fiber electrode (CFE). SEM images confirmed the surface modification and elemental composition analysis demonstrated an increase in the C/O ratio favoring higher conductivity and electron-transfer rate. Nanoporous CFEs were first used for electrochemical oxidation and reduction of H2O2 and results were compared with those of unmodified CFEs. Oxidation current drastically increased with heat treatment and unlike unmodified CFEs, nanoporous CFEs demonstrated a concentration-dependent current change for the reduction of H2O2. Next, the performance of nanoporous CFEs was assessed for DA detection in comparison to unmodified CFEs and they showed remarkable electrocatalytic activity in terms of both sensitivity and selectivity. The nanoporous CFEs have great potential to be used in various applications ranging from measurements in localized volumes to tissue analysis.

The H2O2-dependent activity of a fungal lytic polysaccharide monooxygenase investigated with a turbidimetric assay

BackgroundLytic polysaccharide monooxygenases (LPMOs) are copper-dependent redox enzymes that cleave recalcitrant biopolymers such as cellulose, chitin, starch and hemicelluloses. Although LPMOs receive ample interest in industry and academia, their reaction mechanism is not yet fully understood. Recent studies showed that H2O2 is a more efficient cosubstrate for the enzyme than O2, which could greatly affect the utilization of LPMOs in industrial settings.ResultsWe probe the reactivity of LPMO9C from the cellulose-degrading fungus Neurospora crassa with a turbidimetric assay using phosphoric acid-swollen cellulose (PASC) as substrate and H2O2 as a cosubstrate. The measurements were also followed by continuous electrochemical H2O2 detection and LPMO reaction products were analysed by mass spectrometry. Different systems for the in situ generation of H2O2 and for the reduction of LPMO’s active-site copper were employed, including glucose oxidase, cellobiose dehydrogenase, and the routinely used reductant ascorbate.ConclusionsWe found for all systems that the supply of H2O2 limited LPMO’s cellulose depolymerization activity, which supports the function of H2O2 as the relevant cosubstrate. The turbidimetric assay allowed rapid determination of LPMO activity on a cellulosic substrate without the need for time-consuming and instrumentally elaborate analysis methods.

Hierarchical Core-Shell Structure of 2D VS2@VC@N-Doped Carbon Sheets Decorated by Ultrafine Pd Nanoparticles: Assembled in a 3D Rosette-like Array on Carbon Fiber Microelectrode for Electrochemical Sensing.

The development of two-dimensional (2D) nanohybrid materials with heterogeneous components in nanoscale and three-dimensional (3D) well-ordered assembly in microscale has been regarded as an effective way to improve their overall performances by the synergistic coupling of the optimized structure and composition. In this work, we reported the design and synthesis of a new type of hierarchically core-shell structure of 2D VS2@VC@N-doped carbon (NC) sheets decorated by ultrafine Pd nanoparticles (PdNPs), which were vertically grown on carbon fiber (CF) and assembled into a unique 3D rosette-like array. The resultant VS2@VC@NC-PdNPs modified CF microelectrode integrated the structural and electrochemical properties of the heterogeneous hybridization of core-shell VS2@VC@NC-PdNPs sheets with a unique rosette-like array structure, and gave rise to a significant improvement in terms of electron transfer ability, electrocatalytic activity, stability, and biocompatibility. Under the optimized conditions, the VS2@VC@NC-PdNPs modified CF microelectrode demonstrated excellent electrochemical sensing performance towards biomarker hydrogen peroxide (H2O2) including a high sensitivity of 152.7 μA cm-2 mM-1, a low detection limit of 50 nM (a signal-to-noise ratio of 3:1), as well as good reproducibility and anti-interference ability, which could be used for the real-time in situ electrochemical detection of H2O2 in live cancer cells and cancer tissue. The remarkable performances of the proposed nanohybrid microelectrode will have a profound impact on the design of diverse 2D layered materials as a promising candidate for electrochemical biosensing applications.

Highly dispersive Pt–Pd nanoparticles on graphene oxide sheathed carbon fiber microelectrodes for electrochemical detection of H2O2 released from living cells

We report a facile strategy for the synthesis of surfactant-free, small and highly dispersive Pt–Pd nanoparticles on graphene oxide (Pt–Pd NPs/GO) by an electroless deposition method, which is sheathed on carbon fiber microelectrodes (CFMs) as an electrochemical sensing platform for highly sensitive and selective detection of hydrogen peroxide (H2O2) released from the living cells. GO serves as the reducing agent and stabilizer for electroless deposition of Pd NPs on the surface of GO owing to its low work function (4.38 eV) and highly conjugated electronic structure. The obtained Pd NPs/GO have a relatively high work function (4.64 eV), and thereby could be used as stabilizer for synthesis of surfactant-free, small and highly dispersive Pt–Pd NPs/GO by chemical reduction of K2PtCl4. The obtained Pt–Pd NPs have a uniform size of 4.0 ± 0.6 nm on the surface of GO. Moreover, the Pt–Pd NPs/GO sheathed CFMs exhibit an excellent electrocatalytic activity for the reduction of H2O2 with a low detection limit of 0.3 μM and good selectivity. These good properties enable the modified microelectrode to detect the H2O2 released from living cells.

In situ growth of chrysanthemum-like NiCo2S4 on MXenes for high-performance supercapacitors and a non-enzymatic H2O2 sensor.

In this work, we developed a novel strategy to couple chrysanthemum-like NiCo2S4in situ-grown MXene hybrids into a three-dimensional (3D) sandwich architecture hybrid as an electrode material for high-performance asymmetric supercapacitors and non-enzymatic H2O2 sensors. In the 3D sandwich architecture hybrid, the NiCo2S4 particles were encapsulated by MXene layers, which enhanced the interlayer space of MXene, significantly improving the electrochemical properties. In particular, the MXene/NiCo2S4 1 : 2 electrode achieved a specific capacitance of 1266 F g-1 at 0.5 A g-1 and maintained 95.21% of its initial value after 10 000 cycles. Furthermore, an asymmetrical supercapacitor was also fabricated using MXene/NiCo2S4 1 : 2 as the positive electrode and activated carbon (AC) as the negative electrode (MXene/NiCo2S4 1 : 2//AC), which exhibited exceptional electrochemical performance. MXene/NiCo2S4 1 : 2//AC exhibited a large specific capacitance of 621 F g-1 at 0.5 A g-1 and energy density of 72.82 W h kg-1 at a power density of 0.635 kW kg-1. In addition, MXene/NiCo2S4 1 : 2 was employed as a non-enzymatic sensor for the electrochemical detection of H2O2, which exhibited a high sensitivity of 0.267 μA μM-1 cm-2 and noteworthy low detection limit of 0.193 μM based on 3 signal-noise ratios. This research provides a facile route for the in situ growth of bimetallic sulfides on MXenes as electrode materials for energy storage and electrochemical detection.

M-Nx (M = Fe, Co, Ni, Cu) doped graphitic nanocages with High specific surface Area for non-enzymatic electrochemical detection of H2O2

N-doped porous-walled graphitic nanocages (NGCs) with high specific surface area have been successfully doped by metallic ions (M2+ = Fe2+, Co2+, Ni2+ or Cu2+) for efficiently detecting H2O2. To increase surface area, NGCs were prepared by partially removing N-doped template inserted in their graphitic layers to sharply create nanopores in graphitic shells of nanocages, which were approached from removing ferrous cores of core-shell precursor (Fe3C@NDC) synthesized from short-time floating catalytic pyrolysis. With high specific surface area (920 m2 g−1), mesopore volume (1.6 cm3 g−1) and good graphitization, the synergistic effects of metallic ions and N-doped structure, which improves their dispersion and increases active sites, plays a very important role in detection of H2O2. Fe-N coordination much easier forms in the condition of our experiment than Co-N, Ni-N and Cu-N, which might lead to better electrochemical performance of Fe-Nx doped graphitic nanocages (Fe-NGCs), including wider linear range (0.001−5 mM), lower LOD (0.53 μM), higher sensitivity (184.4 μA mM−1 cm-2), selectivity and stability. Such results demonstrate Fe-NGCs nanocomposite is a promising candidate for the detection of H2O2 in practical application.

Sonochemical synthesis and anchoring of zinc oxide on hemin-mediated multiwalled carbon nanotubes-cellulose nanocomposite for ultra-sensitive biosensing of H2O2.

In this work, the metal oxide and biopolymer nanocomposites on multiwalled carbon nanotubes (MWCNT) were prepared using a simple sonochemical method. The hexagonal nanorods of zinc oxide (ZnO NR) were synthesized by probe sonication (frequency=20kHz, amplitude=50) method and were integrated on ultrasonically functionalized MWCNT-cellulose nanocrystals (MWCNT-CNC) for the first time. The stable hemin bio-composites also were prepared using the bath sonication (37kHz of frequency, 150W of power) method, and was used for the selective and ultrasensitive electrochemical detection of H2O2. The UV-Vis spectroscopy studies confirmed the presence of native hemin on MWCNT-CNC/ZnO NR nanocomposite. Cyclic voltammetry studies revealed that an enhanced redox electrochemical behaviour of hemin was observed on hemin immobilised MWCNT-CNC/ZnO NR nanocomposite than that of other hemin modified electrodes. Also, the MWCNT-CNC/ZnO NR/hemin modified SPCE showed 2.3 folds higher electrocatalytic activity with a lower reduction potential (-0.2V) towards H2O2 than that of other investigated hemin modified electrodes including hemin/MWCNT and hemin/CNC-ZnO. The fabricated biosensor displayed a stable amperometric response (-0.2V vs Ag/AgCl) in the linear concentration of H2O2 ranging up to 4183.3µM with a lower detection limit of 4.0nM.

Fabrication of Pd Nanocubes@CdIF-8 catalysts for highly efficient electrocatalytic sensing of H2O2 and high-performance supercapacitor

In this work, the Pd@ Cd(2-methylimidazole)2 (Pd@CdIF-8) was synthesized by two facile methods, in which the original cubic Pd nanoparticles anchored on the surface/interface of CdIF-8 and supported on the acidified activated carbon (AAC). Interestingly, CdIF-8 exhibited sphericity under hydrothermal condition and presented hexahedron under mild liquid. A(B)-PdxCdyIF-8@AAC hybrids are researched by FESEM, TEM, contact angle measurement, XPS, XRD and BET analytical techniques. A(B)-PdxCdyIF-8@AAC hybrids are employed as nonenzymatic sensors for electrochemical detection of H2O2, and both exhibited excellent electrocatalytic activity, especially for A(B)–Pd0.2Cd1.5IF-8@AAC/GCE sensors. A(B)–Pd0.2Cd1.5IF-8@AAC/GCE sensors demonstrated a linear response to H2O2 in the range of from 10 μM to 10.2 mM and 2 μM to 17.5 mM, the sensitivity of 0.195 μAμM−1 and 0.266 μAμM−1, respectively. In addition, asymmetric supercapacitors have been fabricated using A(B)-PdxCdyIF-8@AAC hybrids as positive electrode and exhibited exceptional electrochemical properties with high specific capacitance (452 F g−1 at 0.05 A g−1 and 372 F g−1 at 1 A g−1 of A-Pd0.2Cd1.5IF-8@AAC, and 502 F g−1 at 0.05 A g−1 and 395 F g−1 at 1 A g−1 of B–Pd0.2Cd1.5IF-8@AAC), excellent stability (83.579% maintenance of specific capacitance at 5 A g−1 of A-Pd0.2Cd1.5IF-8@AAC and 78.313% maintenance of B–Pd0.2Cd1.5IF-8@AAC), respectively.

Protein-Based Nanobiosensor for Electrochemical Determination of Hydrogen Peroxide

We designed a hydrogen peroxide biosensor. The electrochemical detection of H2O2 was performed based on immobilization of cobalt nanoparticles–ferritin (CoNPs–Fer) onto multiwalled carbon nanotubes (MWCNTS) ensnared into chitosan (CS) matrices. Electrochemical techniques such as differential pulse voltammetry (DPV) and cyclic voltammetry (CV) was used to check the property of biosensor. Energy-dispersive X-ray spectroscopy (EDXS) and field emission scanning electron microscopy (FESEM) techniques showed the prosperous immobilization of CoNPs–Fer on the modified GC electrode surface. The hydrogen peroxide-designed biosensor displayed a linear range from 0.2 to 14 nM (R2 = 0.99), a detection limit of 1.29 nM (S/N = 3) and sensitivity of –0.1105 μA/nM.The apparent heterogeneous electron transfer rate constant (Ks) and the charge transfer coefficient (α) were gained 4.19 s–1 and 0.49, respectively. This biosensor can detect hydrogen peroxide with high sensitivity, selectivity, and low detection limit.

Determination of H2O2 in Human Serum Samples with Novel Electrochemical Sensor Based on V2O5/VO2 Nanostructures

Background: Highly selective and sensitive analysis of hydrogen peroxide (H2O2) has attracted considerable interest in the fields of clinical diagnostics, food industry, and environmental analysis. Objectives: In the present study, an efficient electrochemical sensor, based on V2O5/VO2 nanostructures, was introduced for measuring hydrogen peroxide (H2O2) in human serum samples. Methods: The characterization of the prepared V2O5/VO2 nanostructures was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). A carbon paste electrode (CPE) modified with V2O5/VO2 was applied for the electrochemical detection of H2O2. Results: The prepared sensor depicted a good linear range from 8 to 215 μM and a low detection limit of 5 μM. Moreover, the modified electrode showed notable anti-interference property and high sensitivity toward H2O2 detection. The suggested method was also successfully applied for the determination of H2O2 in human serum samples. Conclusions: The V2O5/VO2 embedded CPE offers good simplicity, sensitivity, and selectivity toward H2O2 determination. In addition, the suggested assay revealed good reproducibility and anti-interference property in the measuring of H2O2.

Modified Microelectrodes for the Detection of Reactive Oxygen Species in Biomedical Studies

It has been long known that hydrogen peroxide (H2O2) as an endogenous reactive oxygen species (ROS) belongs to a group of destructive molecules that can lead to protein oxidation, lipid peroxidation, and DNA damage. Whereas elevated ROS production leads to oxidative stress, it was also recently shown that at lower physiological levels, H2O2 acts as an intracellular signalling molecule regulating kinase-driven pathways1. As the involvement and concentration levels of H2O2 at the cellular level are not fully understood, its localized detection at a cellular level is of particular importance. Fluorescent redox-sensitive dyes are frequently used for the detection of H2O2 at the cellular level. H2O2 can also be detected electrochemically, e.g. at anodic potentials (0.6 V vs. Ag/AgCl) at Platinum (Pt) electrodes. However, such high oxidation potential can be affected by co-oxidizable substances such as ascorbic acid, catecholamine etc., which may be present in biological samples2. In this contribution, we present strategies of electrochemical H2O2 detection avoiding such interference problems based on electrocatalytically or enzyme-modified electrodes. Modification with Platinum black3 or Prussian Blue (PB)4 enables the detection at lower potential such as 0.3 V vs. Ag/AgCl at Pt-black modified electrodes and 0.0 V vs Ag/AgCl at PB modified electrodes, respectively. In particular, Prussian Blue (PB) modified electrodes show higher activity and significant higher electrochemical rate constants along with enhanced sensitivity. Hyperoxia treatment is controversial particularly in traumatic brain injury (TBI), due to increased radical and catecholamine production. To study increased release of ROS, measurements at porcine granulocytes and peripheral blood mononuclear cells will be presented using such modified microelectrodes. In addition, the co-detection of catecholamines such as epinephrine using dual sensors will be addressed. In order to study release at the single cell level, we recently introduced conductive colloidal AFM-SECM probes5, which serve as electrochemical transducers for the modification with Platinum black or Prussian Blue (PB) allowing the accurate provisioning of the biosensor at the cell surface.

A novel biosensor with the use of polypyrrole–poly(sodium-4-styrenesulphonate) as a dopant in the determination of glucose

In this paper, a new amperometric biosensor based upon a conducting polymer with anionic dopant-modified electrode was developed for use in the determination of glucose. Glucose oxidase enzyme was immobilized in polypyrrole–poly(sodium-4-styrenesulphonate) film using the entrapment method. Amperometric determination is based on the electrochemical detection of H2O2 generated in the enzymatic reaction of glucose oxidase. Glucose detection was carried out according to the oxidation of hydrogen peroxide at 0.4 V resulting from the enzymatic reaction on the biosensor surface. Some parameters that affect amperometric response current were investigated in terms of temperature, pH, and substrate concentration. The stability and reproducibility of the biosensor were analyzed. The interference effects were examined using amperometric response of the biosensor. The glucose detection ability of the biosensor was tested in a biological fluid (in blood). The film thickness, morphology, and water contact angle measurements of the polypyrrole–poly(sodium-4-styrenesulphonate) film were characterized by profilometer, atomic force microscope, and water contact angle device, respectively. For the biosensor in this study, the linear range 1 × 10−8–1 × 10−3 M, optimum temperature 25 °C, optimum pH 8, Km value 2.97 mM and Vmax value 0.097 μA was found. The results of the study show that the film can provide suitable biological application and electrochemical microenvironment for immobilization of the enzymes, making this material a perfect candidate for the production of extremely susceptible and selective glucose biosensors.

Electrochemical Detection of H₂O₂ Using Copper Oxide-Reduced Graphene Oxide Heterostructure.

Three dimensional heterostructure of CuO nanoparticle decorated reduced graphene oxide (rGO) was prepared by a facile and cost-effective technique. The structure and electrochemical properties of the CuO-rGO heterostructure composites were evaluated by various techniques. Transmission electron microscopy image analysis confirmed the presence of CuO nanoparticles onto the surface of the rGO sheets. It was also noticed that the electrochemical properties were dependent on the morphology of the heterostructure. The CuO-rGO heterostructure showed better hydrogen peroxide sensing performance as compared to the pure CuO nanoparticle. The sensitivity and limit of detection (LoD) were found to be 57.6 μA mM-1 cm-2 and 4.3 nM. The CuO-rGO heterostructure also showed good selectivity in the presence of various interfering electrolytes like ascorbic acid, dopamine, uric acid and glucose.

AuPt/MOF-Graphene: A Synergistic Catalyst with Surprisingly High Peroxidase-Like Activity and Its Application for H2O2 Detection.

Here, we report ZIF-8-reduced graphene oxide (ZIF-8-rGO)-supported bimetallic AuPt nanoparticles (AuPtNPs) as a novel peroxidase mimic for high-sensitivity detection of H2O2 in neutral solution. ZIF-8-graphene oxide (ZIF-8-GO) is first synthesized via a simple wet-chemistry process and subsequently immobilized with AuPtNPs via a reduction method. The resultant AuPt/ZIF-8-rGO shows enhanced peroxidase-like catalytic activity and it is applied for the electrochemical detection of H2O2 in a wide concentration range, from 100 nM to 18 mM, with a very low detection limit of 19 nM (S/N = 3). This good electroanalytical performance of AuPt/ZIF-8-rGO is owing to the ultrasmall size and high dispersion of the AuPtNPs, the strong metal-support interaction between the AuPtNPs and ZIF-8-rGO bisupport, and the sandwich-like structure comprising porous ZIF-8 and loosely packed rGO nanosheets. The AuPt/ZIF-8-rGO is employed for the practical detection of H2O2 in human serum samples with desirable properties. Therefore, the novel AuPt/ZIF-8-rGO is a promising nanozyme for various biotechnological and environmental applications.

Electrochemical assay of hydrogen peroxide based on hybrids of Co3O4/biomass-derived carbon

In this work, Co3O4 was synthesized by a simple hydrothermal and subsequent calcination treatment for electrochemical detection of H2O2. In order to improve the electrochemical performance of Co3O4, it is compounded with the carbon materials derived from cypress leaves, loofah sponge, and pine needles. The electrochemical tests suggested that Co3O4/loofah sponge-derived carbon showed higher electrochemical activity towards H2O2 than the other two composites. The sensor based on Co3O4/loofah sponge-derived carbon exhibited a broad linear range from 5.00 μM to 11.40 mM, with a sensitivity of 47.83 μA mM−1 cm−2 and a detection limit of 1.50 μM (S/N = 3). Thus, this novel nonenzymatic sensor had potential application in H2O2 detection.