Could Carbonaceous Impurities in Reduced Graphenes be Responsible for Some of Their Extraordinary Electrocatalytic Activities?

Wang, Lu; Ambrosi, Adriano; Pumera, Martin

doi:10.1002/asia.201300122

Cited by 21 publications

(16 citation statements)

References 62 publications

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“…In addition to metallic impurities, carbonaceous impurities in GN were also reported to significantly impact its electrochemical performance 180. 207, 214 For example, after the removal of the carbonaceous oxidative impurities from GN,207 the specific capacitance of purified GN is lower than that of unpurified GN (GN was prepared by GO electroreduction215 and GO was synthesized by Hummers’ method)208 but similar to that of pure GN 216. It was implied that the presence of the carbonaceous impurities might increase the wettability and prevent the risk of restacking of GN sheets if they were deposited on the electrode surface, and so that the increased surface area of GN thus enhanced the charge adsorption on the surface of GN and improve its capacitor performance 207…”

Section: Advanced Electrochemical Sensors Based On Graphene (Gn)mentioning

confidence: 99%

Structure–Activity Relationship of Tumor‐Selective 5‐Substituted 2‐Amino‐3‐carboxymethylthiophene Derivatives

et al. 2014

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Methyl-2-amino-5-[2-(4-methoxyphenethyl)]thiophene-3-carboxylate (8 c) is the prototype of a well-defined class of tumor-selective agents. Compound 8 c preferentially inhibited the proliferation of a number of tumor cell lines including many human T-lymphoma/leukemia cells, but also several prostate, renal, central nervous system and liver tumor cell types. Instead, a broad variety of other tumor cell lines including B-lymphomas and HeLa cells were not affected. The tumor selectivity (TS; selectivity index or preferential suppression of CEM lymphoma (IC50 =0.90 μM) versus HeLa tumor cell carcinoma (IC50 =39 μM)) amounted up to ~43 for 8 c. At higher concentrations, the compound proved cytotoxic rather than cytostatic. The antiproliferative potency and selectivity of 8 c could be preserved by replacing the ethyl linker between the 2-amino-3-carboxymethylthiophene and the substituted aryl by a thioalkyl but not by an oxyalkyl nor an aminoalkyl. Among >50 novel 8 c derivatives, the 5-(4-ethyl- and 4-isopropylarylmethylthio)thiophene analogues, methyl-2-amino-5-((4-ethylphenylthio)methyl)thiophene-3-carboxylate (13 m) and methyl-2-amino-5-((4-isopropylphenylthio)methyl)thiophene-3-carboxylate (13 n), were more potent (IC50 : 0.3-0.4 μM) and selective (TS: 100-144) anti-T-lymphoma/leukemia agents than the prototype compound.

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Section: Advanced Electrochemical Sensors Based On Graphene (Gn)mentioning

confidence: 99%

Structure–Activity Relationship of Tumor‐Selective 5‐Substituted 2‐Amino‐3‐carboxymethylthiophene Derivatives

et al. 2014

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“…Several authors have studied the effect of CF on the electrochemical performance of CNT and graphene materials . The presence of CF was reported to have a positive effect on the electrochemical oxidation of β‐nicotinamide adenine dinucleotide (NADH) and ascorbic acid (AA) at a glassy carbon electrode coated with CNT .…”

Section: Introductionmentioning

confidence: 99%

“…[29][30][31][32] Several authors have studied the effect of CF on the electrochemicalp erformance of CNT and graphene materials. [32][33][34][35][36][37][38][39] The presence of CF was reportedt oh ave ap ositive effect on the electrochemical oxidation of b-nicotinamide adenine dinucleotide (NADH) and ascorbic acid (AA) at ag lassy carbon electrode coated with CNT. [32] Conversely,t he oxidation of NADH mediated by 1,10-phenantroline-5,6-dione wasa dversely influenced by the presence of CF on the GO surface.…”

Section: Introductionmentioning

confidence: 99%

Role of Carbonaceous Fragments on the Functionalization and Electrochemistry of Carbon Materials

et al. 2016

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Carbonaceous fragments (CF) formed by acid treatment of carbon materials have important properties that are not completely understood. In this work, CF were produced by oxidation of CNT by using mineral acid followed by treatment with NaOH. The role of CF on CNT voltammetric properties was studied by using different materials: oxidized CNT (a‐CNT), a‐CNT refluxed in NaOH and neutralized with HCl (b‐CNT), pristine CNT exposed to a CF suspension (c‐CNT), and b‐CNT exposed to a CF suspension (r‐CNT). The extension of functionalization of these materials was evaluated by thermogravimetric analysis (TGA). The spectroscopic characterization (UV/Vis, fluorescence, FTIR, Raman and NMR) of CF indicates the presence of graphene‐type conjugated aromatic rings with highly oxidized moieties. In this work we demonstrate that CF are responsible for the ameliorated voltammetric properties of oxidized CNT. Adsorption of CF on oxidized and non‐oxidized CNT showed that CF provide active sites for hydroquinone (HQ) adsorption, enhancing current responses. The interaction of CF with carbon materials depended on both the surface oxidation degree and the surface roughness. Voltammograms from CF adsorbed on oxidized CNT indicate the presence of labile supramolecular structures with a voltammetric response typical of quinoid units. Carbon materials functionalized with CF displayed lower peak potentials and higher currents (30 to 180 %) than the unmodified electrodes, demonstrating that CF is a promising material for sensors design.

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“…Pumera’s group has demonstrated before that single‐, few‐, and multilayer graphenes do not exhibit significant advantages over graphite microparticles in connection with the measurement of ascorbic acid and uric acid 27. They further pointed out that the carbonaceous impurities in the form of amorphous carbon within graphene samples were responsible for the observed electrocatalytic effects of the graphene surfaces towards important compounds, such as NADH, hydroquinone, and acetaminophen 28. Recently, the group has revealed that residual metal impurities (Fe, Co, and Ni) present in graphene are responsible for the electrocatalytic properties towards several molecular probes, such as NaSH, l‐glutathione, cumene hydroperoxide, and hydrazine 29.…”

mentioning

confidence: 99%

“…[27] They further pointedo ut that the carbonaceous impurities in the form of amorphous carbon within graphene samplesw erer esponsible for the observed electrocatalytic effects of the graphenes urfaces towardsi mportant compounds, such as NADH, hydroquinone, and acetaminophen. [28] Recently, the group has revealed that residualm etal impurities (Fe, Co, andN i) present in graphene are responsible for the electrocatalytic properties towardss everalm olecular probes, such as NaSH,l -glutathione, cumene hydroperoxide, and hydrazine. [29] These discoveries suggest that the electrocatalysiso fg raphenem ay be induced by heterogeneous substances present in graphene sheets rathert han graphene itself.…”

mentioning

confidence: 99%

Electrocatalytic Activities of Chemically Reduced Graphene Are Essentially Dominated by the Adhered Carbonaceous Debris

Zhu

2015

Chemistry A European J

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Due to its simple, scalable, and facile qualities, the chemical reduction of graphene oxide seems to be the most popular approach to prepare graphene. We show that such prepared graphene is strongly adhered with carbonaceous debris that has been produced during the synthesis of graphene oxide by the chemical exfoliation of graphite and still remain on graphene sheets through the chemical reduction steps. Interestingly, the presence of the carbonaceous debris causes a significant impact on the electrochemical behavior of the chemical reduced graphene. Herein, we demonstrate that the electrocatalytical activities of the graphene are greatly boosted by the adhered carbonaceous debris. After the removal of the carbonaceous debris, the electrocatalysis of graphene is not superior to conventional graphite.

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Could Carbonaceous Impurities in Reduced Graphenes be Responsible for Some of Their Extraordinary Electrocatalytic Activities?

Cited by 21 publications

References 62 publications

Structure–Activity Relationship of Tumor‐Selective 5‐Substituted 2‐Amino‐3‐carboxymethylthiophene Derivatives

Structure–Activity Relationship of Tumor‐Selective 5‐Substituted 2‐Amino‐3‐carboxymethylthiophene Derivatives

Role of Carbonaceous Fragments on the Functionalization and Electrochemistry of Carbon Materials

Electrocatalytic Activities of Chemically Reduced Graphene Are Essentially Dominated by the Adhered Carbonaceous Debris

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