PDF Publication Title:
Text from PDF Page: 007
Fig. 3 Digital photoimage of transparent nitrogen doped graphene film floating on water. Rotating disc voltammograms for electrochemical reduction of oxygen in air-saturated 0.1 M KOH. Rotation speed 1000 rpm, scan rate 0.01 V s1, all masses of the material the same 1⁄4 7.5 mg. Reproduced with permission from ref. 46. electrochemical properties of the composite film modified GCE were investigated. It was found that the prepared Nafion-G composite film not only exhibited improved sensitivity for the metal ion detections, but also alleviated the interferences due to the synergistic effect of graphene nanosheets and Nafion. The linear calibration curves ranged from 0.5 to 50 mg L1 for Pb2+ and 1.5 to 30 mg L1 for Cd2+, respectively. The detection limits (S/N 1⁄4 3) were estimated to be around 0.02 mg L1 for Pb2+ and Cd2+. Fig. 4 depicts the analytical performance of the Nafion (dotted line) film coated GCE with that of a Nafion–graphene (solid line) coated GCE both plated with a bismuth film and evaluated towards the sensing of lead and cadmium. The authors report sharper and higher peak currents for the target metal ions using the Nafion–graphene modified electrode, where an improvement of 79% is observed in comparison to a Nafion coated electrode. Additionally, using a CNT/Nafion modified electrode, a 69% improvement was observed, indicating a similar behaviour to graphene. Also shown in Fig. 4 are SEM images of the Nafion and Nafion–graphene which are distinctively different. The Nafion modified electrode shows a flat and homogeneous film while the Nafion–graphene composite film exhibits a rough and stratified structure—allowing a more effective active area for the nucleation of the bismuth due to this unique structure.47 Impedance changes of the electrode surfaces were conducted where it was found that when compared with that of the pure Nafion modified electrode, the electron-transfer resistance of the Nafion–graphene modified electrode was reduced greatly, sug- gesting the interfusion of the graphene into the Nafion film greatly reduced electron-transfer-limited process; due to the high conductivity resulting from the extensive conjugated sp2 carbon network.47 Thus the observed signal enhancement, as depicted in Fig. 4, is attributed by the authors47 to two factors: (i) the change of the morphologies and the structure, and (ii) the interfacial electron-transfer properties.47 Note, as with CNTs, care should be taken in identifying what enhancements are simply due to increased surface area. The authors report detection limits around 20 ng L1 for lead and cadmium, which appears to be more sensitive than previously reported Nafion film modified bismuth electrodes; 100 ng L1 for lead and cadmium48 and yet comparable to CNT/Nafion coated bismuth film electrodes; 25 ng L1 for lead and 40 ng L1 for cadmium.49 Recently this has been extended for graphene oxide–Nafion nanocomposite film modified GCEs for the sensing of cadmium; with a reported Fig. 4 (A) DPASVs for 20 mg L1 each of Cd2+ and Pb2+ on an in situ plated Nafion–BFE, Nafion-G–BFE in solution containing 1 mg L1 Bi3+, (B) SEM image of Bi film deposited on the Nafion (a) and Nafion-G (b) modified GCE. Supporting electrolyte: 0.1 M acetate buffer (pH 4.5); deposition potential: 1.2 V; deposition time: 120 s; amplitude: 80 mV; increment potential: 5 mV; quiet time: 10 s. Reproduced with permission from ref. 47. This journal is a The Royal Society of Chemistry 2010 Analyst, 2010, 135, 2768–2778 | 2773 View Article Online Published on 04 October 2010. Downloaded by Manchester Metropolitan University on 18/07/2015 16:37:37.PDF Image | Graphene Electrochemistry
PDF Search Title:
Graphene ElectrochemistryOriginal File Name Searched:
c0an00590h.pdfDIY PDF Search: Google It | Yahoo | Bing
Salgenx Redox Flow Battery Technology: Power up your energy storage game with Salgenx Salt Water Battery. With its advanced technology, the flow battery provides reliable, scalable, and sustainable energy storage for utility-scale projects. Upgrade to a Salgenx flow battery today and take control of your energy future.
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)