Regulatory Peptides Are Susceptible to Oxidation by Metallic Impurities within Carbon Nanotubes

Ambrosi, Adriano; Pumera, Martin

doi:10.1002/chem.200902534

Cited by 79 publications

(63 citation statements)

References 47 publications

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“…Such metal contaminations can dramatically influence the electrochemical behavior of the materials. It has already been demonstrated, in fact, how metallic impurities influence the electrochemical properties of carbon nanotubes (24)(25)(26)(27)(28), even at ppm levels (38). We recently demonstrated an altered electrochemical behavior of thermally exfoliated graphene by comparing the electrochemistry of such material with that of edge-plane-pyrolitic graphite electrode (EPPG) (37).…”

Section: Resultsmentioning

confidence: 99%

“…The influence of metallic impurities has already been demonstrated for carbon nanotubes (CNTs) produced by CVD on metallic nanoparticle catalysts. It was clearly shown that residual metallic impurities present in CNT samples can alter and even dominate their electronic (22,23), electrochemical (24)(25)(26)(27), redox (28)(29)(30), adsorption (31) and toxicological properties (32,33). However, research on the effects of impurities in graphene and graphene-related materials is still in its earliest stage despite the important implications of these impurities-implications including the possibility of altering the electrochemical and electronic behavior or toxicity of graphenes because these materials are being used as electrode surfaces (6) or tracers in cancer imaging (34).…”

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confidence: 99%

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Chemically reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite

Ambrosi

Chua

Khezri

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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207

168

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Graphene-related materials are in the forefront of nanomaterial research. One of the most common ways to prepare graphenes is to oxidize graphite (natural or synthetic) to graphite oxide and exfoliate it to graphene oxide with consequent chemical reduction to chemically reduced graphene. Here, we show that both natural and synthetic graphite contain a large amount of metallic impurities that persist in the samples of graphite oxide after the oxidative treatment, and chemically reduced graphene after the chemical reduction. We demonstrate that, despite a substantial elimination during the oxidative treatment of graphite samples, a significant amount of impurities associated to the chemically reduced graphene materials still remain and alter their electrochemical properties dramatically. We propose a method for the purification of graphenes based on thermal treatment at 1,000°C in chlorine atmosphere to reduce the effect of such impurities on the electrochemical properties. Our findings have important implications on the whole field of graphene research.electrochemistry | synthesis G raphene and graphene-derived materials have recently attracted enormous attention from the scientific community because of their extraordinary physical, chemical, and mechanical features (1, 2). Graphene materials can be used in several applications-including electronics (3), composite materials (4, 5), sensing (6), energy storage (7,8), and medicine (9)-with expected or known advantages over conventional materials.In general, there are two routes leading to the production of graphene: (i) a bottom-up approach, consisting of growing single/ bilayered graphene onto a catalytic surface through chemical vapor deposition (CVD) technique (10, 11); and (ii) a top-down approach, starting from graphite to obtain single/few-layered graphene sheets by an exfoliation procedure (12, 13). Because exfoliation in the liquid phase is hardly achieved directly on graphitic materials because of the highly cohesive van der Waals forces between the graphene sheets (14), a chemical treatment is generally performed to oxidize graphite to graphite oxide (GO). The oxidation helps to increase the graphene interlayer distance for an easy exfoliation, which is then followed by the removal of the oxygen functionalities to give single/few-layered graphene (12). The second approach received particularly huge attention because it is suitable for large-scale production of graphene materials and is cost-effective, although the graphene produced presents significant structural defects and lower carrier mobility properties (12). Natural graphite is the preferred starting material for this method of preparation because it is available in great quantities and at a low cost. Alternatively, synthetic graphite is also widely adopted as a starting material. It is important to highlight the differences between these two graphitic materials with particular focus on the content of metallic impurities and possible sources of contamination.Natural graphite is mined using standard ...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Chemically reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite

Ambrosi

Chua

Khezri

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

207

168

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“…This situation is reminiscent of the state of carbon nanotube (CNT) research about a decade ago, during which many groundbreaking properties, such as electrocatalytic effects, were initially ascribed to CNTs; these properties were later proven to arise from the presence of residual metallic catalyst impurities within them. The dominant effects of metallic impurities in CNT have been extensively documented in many areas, including electrocatalysis (30)(31)(32)(33)(34)(35), toxicity studies (36,37), and…”

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confidence: 99%

Synthetic routes contaminate graphene materials with a whole spectrum of unanticipated metallic elements

Wong

Sofer²,

Kubešová

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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145

118

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The synthesis of graphene materials is typically carried out by oxidizing graphite to graphite oxide followed by a reduction process. Numerous methods exist for both the oxidation and reduction steps, which causes unpredictable contamination from metallic impurities into the final material. These impurities are known to have considerable impact on the properties of graphene materials. We synthesized several reduced graphene oxides from extremely pure graphite using several popular oxidation and reduction methods and tracked the concentrations of metallic impurities at each stage of synthesis. We show that different combinations of oxidation and reduction introduce varying types as well as amounts of metallic elements into the graphene materials, and their origin can be traced to impurities within the chemical reagents used during synthesis. These metallic impurities are able to alter the graphene materials' electrochemical properties significantly and have wide-reaching implications on the potential applications of graphene materials.

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“…To construct robust and fast prepared paste electrodes having direct electrical contact between the SCNR particles, we decided to blend the SCNR "whiskers" with PB. Note that the use of these nanomaterials allows one to deconvolute the true electrochemical parameters avoiding contributions from metallic impurities [4,[7][8][9][10]. The PB composite electrodes are evaluated towards the electroanalytical sensing of hydrogen peroxide and compared critically to that of simple graphite; surprisingly we find no advantage of using the SCNR "whiskers" in this context.…”

Section: Introductionmentioning

confidence: 89%

“…This is due to the different crystallographic and chemical influences affecting the electrochemical properties of carbon nanotubes [4]. As Compton et al [5,6], Banks et al [4,7,8], and later Pumera et al [9,10] have demonstrated, metallic impurities reside in carbon nanotubes which is inherent to their fabrication process can be responsible for the CNTs observed electroactivity towards selected analytes; for example, Banks et al [11] concluded for the case of the electrochemical detection of D-glucose that the effect of metallic impurities dominates over edge plane crystallographic effects of the graphite edge plane like-sited/defects.…”

Section: Introductionmentioning

confidence: 99%

Prussian Blue Modified Solid Carbon Nanorod Whisker Paste Composite Electrodes: Evaluation towards the Electroanalytical Sensing ofH2O2

Siimenson

Kruusma

Anderson

et al. 2012

International Journal of Electrochemistry

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Metallic impurity free solid carbon nanorod "Whiskers" (SCNR Whiskers), a derivative of carbon nanotubes, are explored in the fabrication of a Prussian Blue composite electrode and critically evaluated towards the mediated electroanalytical sensing of H 2 O 2 . The sensitivity and detection limits for H 2 O 2 on the paste electrodes containing 20% (w/w) Prussian Blue, mineral oil, and carbon nanorod whiskers were explored and found to be 120 mA/(M cm 2 ) and 4.1 μM, respectively, over the concentration range 0.01 to 0.10 mM. Charge transfer constant for the 20% Prussian Blue containing SCNR Whiskers paste electrode was calculated, for the reduction of Prussian Blue to Prussian White, to reveal a value of 1.8 ± 0.2 1/s (α = 0.43, N = 3). Surprisingly, our studies indicate that these metallic impurity-free SCNR Whiskers, in this configuration, behave electrochemically similar to that of an electrode constructed from graphite.

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Regulatory Peptides Are Susceptible to Oxidation by Metallic Impurities within Carbon Nanotubes

Cited by 79 publications

References 47 publications

Chemically reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite

Chemically reduced graphene contains inherent metallic impurities present in parent natural and synthetic graphite

Synthetic routes contaminate graphene materials with a whole spectrum of unanticipated metallic elements

Prussian Blue Modified Solid Carbon Nanorod Whisker Paste Composite Electrodes: Evaluation towards the Electroanalytical Sensing ofH2O2

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