Graphene Oxide Nanocomposite Electrode Research Articles

Nanomolar level detection of non-steroidal antiandrogen drug flutamide based on ZnMn2O4 nanoparticles decorated porous reduced graphene oxide nanocomposite electrode

Flutamide is a non-steroidal antiandrogen drug and widely used in the treatment of prostatic carcinoma. Nevertheless, the excessive intake and improper disposal could affect the living organisms. In this work, we have synthesized a new nanocomposite based on ZnMn2O4 nanoparticles and porous reduced graphene oxide nanosheets (ZnMn2O4-PGO) for the electrocatalytic detection of flutamide (FLU) drug. The crystallinity and morphological properties of ZnMn2O4-PGO composite examined by different characterization techniques such as X-ray diffraction, Raman spectroscopy and so on. The fabricated ZnMn2O4-PGO nanocomposite modified electrode exhibited superior electrocatalytic performance to FLU drug in an optimized pH electrolyte. Fascinatingly, the electrode received a wide linear range (0.05–3.5 µM) with limit of detection of 8 nM. Besides, the developed ZnMn2O4-PGO nanocomposite electrode showed good sensitivity 1.05 µAµM−1 cm−2 and excellent selectivity for FLU detection in presence of various interfering species. A developed disposable electrode was scrutinized to determine FLU level in human urine samples by spiking method and the results achieved good recoveries in real sample analysis.

Multilayered iron oxide/reduced graphene oxide nanocomposite electrode for voltammetric sensing of bisphenol-A in lake water and thermal paper samples

A multilayered iron oxide/reduced graphene oxide (ION-RGO) nanocomposite electrode is reported for the voltammetric sensing of bisphenol-A (BPA). Structural characterizations reveal the nanocomposite features RGO sheets decorated with nanometric spherical ION in a mixture of maghemite and magnetite phases. ITO substrate modified with the ION-RGO multilayered film exhibits strong electrocatalytic effect toward BPA oxidation, which is made possible by Fe(III) catalysts generated at the ION's surface after scanning the electrode potential from below 0 V (vs Ag/AgCl) and followed by the RGO phase conducting the transferred electrons. Under optimized differential pulse voltammetry conditions, the proposed sensor shows three linear working ranges 0.09–1.17 (r2 = 0.999), 1.17–3.81 (r2 = 0.995) and 3.81–8.20 (r2 = 0.998), with the highest sensitivity equaling 7.76 μA cm−2/μmol L−1 and the lowest limit of detection of 15 nmol L−1. A single electrode can be used for at least twenty consecutive runs loosing less than 15% of sensitivity, whereas electrodes fabricated in different bacthes exhibit almost identical perfomances. Determination of BPA in a thermal paper sample shows no difference (at 95% confidence level) between the proposed sensor and HPLC/UV. The sensor is neither influenced by the matrix composition nor by other emerging contaminants.

Electrochemical Behavior of Cobalt Oxide/Boron-Incorporated Reduced Graphene Oxide Nanocomposite Electrode for Supercapacitor Applications

Electrodes from hydrothermally synthesized boron-incorporated reduced graphene oxide (B-rGO), Co3O4, and Co3O4/B-rGO nanocomposites are tested in 2 M KOH and NaOH electrolytes for supercapacitor applications. Structural characterization was done by x-ray diffraction and x-ray photoelectron spectroscopy. Cyclic voltammogram of B-rGO indicates partial electrical double-layer capacitance and pseudocapacitive behaviors. Co3O4, shows two reversible redox peaks, indicating diffusion-controlled (battery-like) process. Interestingly, Co3O4/B-rGO possesses both the pseudocapacitive and diffusion-controlled features. The specific capacitance (Csp) from galvanostatic charge/discharge experiments is higher in all the electrodes in KOH than in NaOH. Co3O4/B-rGO shows the highest Csp of 600 F g−1 (270 C g−1) at 0.1 A g−1 and 454 F g−1 (204 C g−1) at 10 A g−1 in KOH. Co3O4/B-rGO-KOH system retains 87.8% capacitance after 2000 cycles, demonstrating very good cyclic stability. Co3O4/B-rGO-KOH system yields, a remarkable, maximum power density of 2250 W kg−1 with an energy density of 12.77 W h kg−1 at 10 A g−1. The better performance in KOH is attributed to the low hydration sphere radius, high ionic conductivity of K+, low diffusive and charge transfer and electrode resistance, estimated from electrochemical impedance spectroscopy. The electrode–electrolyte combination is crucial for the overall performance as a supercapacitor electrode.

Selective removal of Cl− and F− from complex solution via electrochemistry deionization with bismuth/reduced graphene oxide composite electrode

Electro-adsorption is attracting increasing attention as an emerging technology for removing ionic species from water but suffer from low selectivity. In this work, a bismuth/reduced graphene oxide nanocomposite electrode was fabricated by a facile and green method. Based on this material, an electrode with improved selectivity by electrochemistry deionization system was successfully fabricated. The bismuth nanoparticles were uniformly covered with reduced graphene oxide plates and the ratio of Bi on the whole materials is 79.56%. Bismuth/reduced graphene oxide showed ions selectivity in the order of Cl− > F− ≫ SO42−. The average Cl− removal capacity can reach as high as 62.59 mg g−1. Moreover, bismuth/reduced graphene oxide electrodes have good regeneration performance. Typically, in the 10 adsorption-desorption multicycles, the salt absorption/desorption capacity of the hybrid capacitive deionization system is stable and reversible. This research opened a hopeful window to design and synthesize effective materials to selectively remove the ionic species to purify the water.

Multiwalled carbon nanotubes /reduced graphene oxide nanocomposite electrode for electroanalytical determination of bisphenol A, 8-hydroxy-2’-deoxyguanosine and hydroquinone in urine

ABSTRACTA simple and convenient strategy for the preparation of electrochemically reduced graphene oxide/multiwalled carbon nanotubes/modified screen-printed carbon electrodes (ERGO/MWCNTs/SPCEs) was developed for the simultaneous electrochemical determinations of bisphenol A (BPA), 8-hydroxy-2ʹ-deoxyguanosine (8-OHdG) and hydroquinone (HQ). The hybrid material ERGO/MWCNTs was characterized by field emission scanning electron microscope (FEG-SEM), micro-Raman spectrometer (Micro-Raman) and X-ray photoelectron spectroscopy (XPS). Differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) showed excellent electron transfer characteristics, low electron transfer resistance, and an increase in the oxidation current at the modified electrode. Under optimum conditions, the linear response ranges for BPA, 8-OHdG and HQ were 0.5–25.0 μmol L−1, 0.05–50.0 μmol L−1 and 0.5–100.0 μmol L−1 with detection limits of 14 nmol L−1, 3 nmol L−1 and 28 nmol L−1 at S/N = 3, respectively. In addition, the reproducibility, stability and anti-interference properties of the modified electrode were also investigated with good results. Finally, this modified electrode was successfully applied in the simultaneous determinations of BPA, 8-OHdG and HQ in human urine, with recoveries that ranged from 95.82 to 106.85% and can be used as an exposure biomarker.

Bismuth Vanadate/Reduced Graphene Oxide Nanocomposite Electrode for Photoelectrochemical Determination of Diclofenac in Urine

AbstractThe nanocomposite material bismuth vanadate and reduced graphene oxide BiVO4/rGO was prepared and deposited onto a fluorine‐doped tin oxide glass surface for application of a photoelectrochemical sensor for the determination of sodium diclofenac in urine samples. This drug is considered as an emergent pollutant because of its ecotoxicological risk when discarded in wastewater. Electrochemistry Impedance Spectroscopy experiments shown that the rGO contributed to the efficiency of the DCF electro‐oxidization and, under irradiation, the resistance in the charge transfer in the work electrode decreased. The sensor presented photocurrent responses during the diclofenac electro‐oxidation under visible light irradiation, with a linear concentration range from 9.6×10−9 mol L−1 to 9.2×10−6 mol L−1 and a LOD of 4.2×10−9 mol L−1. The presence of the drug in urine was successfully determined by recovery in spiked samples.

A wearable electrochemical glucose sensor based on simple and low-cost fabrication supported micro-patterned reduced graphene oxide nanocomposite electrode on flexible substrate

In this study, a reduced graphene oxide (rGO)-based nanostructured composite working electrode of high quality was successfully microfabricated and micro-patterned on a flexible polyimide substrate using simple low-cost fabrication processes. Gold and platinum alloy nanoparticles were electrochemically deposited onto the microfabricated rGO surface and chitosan-glucose oxidase composites were integrated onto the modified surface of the working electrode to develop a human sweat-based wearable glucose sensor application. The fabricated biosensor exhibited excellent amperometric response to glucose at a detection range of 0–2.4 mM (covers the glucose range in sweat), with a sensitivity of 48 μA/mMcm2, a short response time (20 s), and high linearity (0.99). The detection limit for glucose was calculated as 5 µm. The human sweat/mixing glucose samples initially used for testing indicated acceptable detection performance and stability for low glucose concentrations. These results confirm that the proposed nanostructured composite flexible working electrode and fabrication process are highly promising for application as human sweat-based electrochemical glucose sensors.

The effective determination of Cd(ii) and Pb(ii) simultaneously based on an aluminum silicon carbide-reduced graphene oxide nanocomposite electrode.

A platform for the simultaneous determination of Cd(ii) and Pb(ii) in aqueous solution has been applied based on an aluminum silicon carbide-reduced graphene oxide nanocomposite (Al4SiC4-RGO) modified bismuth film glassy carbon electrode (GCE) using square wave anodic stripping voltammetry (SWASV) for the first time. The Al4SiC4-RGO nanocomposite electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with the Al4SiC4 modified GCE and bare GCE, the electrochemical performance of the Al4SiC4-RGO nanocomposite electrode is obviously enhanced resulting from the synergistic effects of Al4SiC4, RGO and bismuth film. The chemical and electrochemical parameters that exert an influence on the deposition and stripping of metal ions, such as supporting electrolytes, pH values, concentrations of Bi3+, deposition potentials and deposition times, were carefully studied. Under optimal conditions, a linear relationship exists between the currents and the concentrations of Cd(ii) and Pb(ii) in the range of 50 to 2700 μg L-1. The limits of detection (S/N = 3) are estimated to be 1.30 μg L-1 for Pb(ii) and 2.15 μg L-1 for Cd(ii). Compared with the related work reported in the literature, the analytical performance in this work has a lower determination limit and a wider detection linear range. In addition, this electrode also exhibits good stability and reproducibility. These results imply that the Al4SiC4-RGO nanocomposite might be a promising candidate for practical applications in the electrochemical detection of metal ions.

Binder‐Free Carbon‐Coated Silicon–Reduced Graphene Oxide Nanocomposite Electrode Prepared by Electrophoretic Deposition as a High‐Performance Anode for Lithium‐Ion Batteries

AbstractA simple yet versatile binder‐free electrophoretic deposition method is developed to fabricate a carbon‐coated Si/reduced graphene oxide (Si@C/rGO) nanocomposite as a high‐performance anode for lithium‐ion batteries. In this nanostructure, high specific capacity Si nanoparticles are uniformly coated with the carbon layer and embedded in graphene sheets to form an integrated, robust and conductive framework. Electrochemical studies show that this nanostructured Si@C/rGO electrode exhibits a high reversible specific capability (1165 mA h g−1 at 0.1 A g−1, three times of that of graphite) and excellent cycling stability (capacity retention of 96.8 % at 1 A g−1, and 95.4 % at 2 A g−1 after 100 cycles).

A sol–gel derived, copper-doped, titanium dioxide–reduced graphene oxide nanocomposite electrode for the photoelectrocatalytic reduction of CO2to methanol and formic acid

Highly efficient photoelectrocatalytic reduction of CO2into methanol and formic acid at Cu doped RGO–TiO2photoelectrode.

Sensitive Detection of Hydroxylamine on Poly(3,4- ethylenedioxythiophene)/graphene Oxide Nanocomposite Electrode

Sensitive Detection of Hydroxylamine on Poly(3,4- ethylenedioxythiophene)/graphene Oxide Nanocomposite Electrode

Nickel-cobalt nanostructures coated reduced graphene oxide nanocomposite electrode for nonenzymatic glucose biosensing

Nickel-cobalt nanostructures (Ni-Co NSs) electrodeposited on reduced graphene oxide (RGO)-modified glassy carbon electrode (GCE) was prepared and used for highly sensitive glucose detection. RGO nanosheets were firstly assembled onto GCE surface by π–π interaction and then Ni-Co NSs were constructed on RGO/GCE by dynamic potential scan. The electrochemical and electrocatalytic behaviors of the Ni-Co NSs/RGO/GCE toward glucose oxidation were evaluated by cyclic voltammograms, chronoamperometry and amperometric method. The effects of some factors related to the fabrication of Ni-Co NSs/RGO/GCE, such as potential scan number and the molar ratio of Ni2+/Co2+ in a solution, on the catalytic performance of the Ni-Co NSs/RGO/GCE were also explored. The results showed that the Ni-Co NSs/RGO/GCE exhibited the best catalytic activity at the potential scan number of 20 and the Ni2+/Co2+ molar ratio of 1:1. The glucose concentration in the range of 10μM to 2.65mM linearly depended on the catalytic current (r=0.9967, n=17). The sensitivity was 1773.61μAcm−2mM−1, and the detection limit was 3.79μM (S/N=3). This high catalytic activity, good sensitivity and stability of the Ni-Co NSs/RGO/GCE sensor opened up a new kind of hybrid materials in electrochemical detection of glucose.

SnO2/Reduced Graphene Oxide Nanocomposite for the Simultaneous Electrochemical Detection of Cadmium(II), Lead(II), Copper(II), and Mercury(II): An Interesting Favorable Mutual Interference

A well-known gas sensing material SnO2 in combination with reduced graphene oxide was used in heavy metal ions detection for the first time. This work reports the detailed study on the SnO2/reduced graphene oxide nanocomposite modified glass carbon electrode, which could be used for the simultaneous and selective electrochemical detection of ultratrace Cd(II), Pb(II), Cu(II), and Hg(II) in drinking water. The SnO2/reduced graphene oxide nanocomposite electrode was characterized voltammetrically using redox couples (Fe(CN)63–/4–), complemented with electrochemical impedance spectroscopy (EIS). Square wave anodic stripping voltammetry (SWASV) has been used for the detection of Cd(II), Pb(II), Cu(II), and Hg(II). The detection limit (3σ method) of the SnO2/reduced graphene oxide nanocomposite modified GCE toward Cd(II), Pb(II), Cu(II) and Hg(II) is 1.015 × 10–10 M, 1.839 × 10–10 M, 2.269 × 10–10 M, and 2.789 × 10–10 M, respectively, which is very well below the guideline value given by the World Health Organ...