A comparison between physically and chemically driven etching in the oxidation of graphite surfaces

Solís‐Fernández, Pablo; Paredes, J.I.; Cosío, A.; Martı́nez-Alonso, A.; Tascón, J.M.D.

doi:10.1016/j.jcis.2010.01.018

Cited by 40 publications

(39 citation statements)

References 42 publications

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“…Studies show that NTPs generated from DBD devices etch surfaces through more-or-less random ion bombardment, resulting in a time-dependent physical deposition of oxygen and nitrogen species from normal atmospheric air (24). Here, we report that analogous physical damage occurs on the surface of multidrug-resistant microbes, ultimately leading to partial cell lysis and the release of intracellular components with longer treatment times.…”

Section: Discussionmentioning

confidence: 72%

“…However, the mechanism through which NTPs inactivate living cells is poorly understood. Several plausible hypotheses exist, including oxidative intracellular/DNA damage, disruption of cellular electrostatic potential, or chemical etching of the cellular surface (24). The lack of a standard protocol for preparing and treating cells with plasma, in addition to technical limitations associated with analyzing cells on surfaces rather than in solution, represent critical impediments for determining the exact mechanism through which NTPs inactivate microbes.…”

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confidence: 99%

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Nonthermal Atmospheric Plasma Rapidly Disinfects Multidrug-Resistant Microbes by Inducing Cell Surface Damage

Kvam

Davis

Mondello

et al. 2012

Antimicrob Agents Chemother

160

111

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Plasma, a unique state of matter with properties similar to those of ionized gas, is an effective biological disinfectant. However, the mechanism through which nonthermal or "cold" plasma inactivates microbes on surfaces is poorly understood, due in part to challenges associated with processing and analyzing live cells on surfaces rather than in aqueous solution. Here, we employ membrane adsorption techniques to visualize the cellular effects of plasma on representative clinical isolates of drug-resistant microbes. Through direct fluorescent imaging, we demonstrate that plasma rapidly inactivates planktonic cultures, with >5 log 10 kill in 30 s by damaging the cell surface in a time-dependent manner, resulting in a loss of membrane integrity, leakage of intracellular components (nucleic acid, protein, ATP), and ultimately focal dissolution of the cell surface with longer exposure time. This occurred with similar kinetic rates among methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Candida albicans. We observed no correlative evidence that plasma induced widespread genomic damage or oxidative protein modification prior to the onset of membrane damage. Consistent with the notion that plasma is superficial, plasma-mediated sterilization was dramatically reduced when microbial cells were enveloped in aqueous buffer prior to treatment. These results support the use of nonthermal plasmas for disinfecting multidrug-resistant microbes in environmental settings and substantiate ongoing clinical applications for plasma devices. P lasmas are ionized gases that exhibit a plethora of applied temperature and physical properties. In biomedical applications, plasmas are supported by an electric field such that electrons receive external energy more rapidly than surrounding ions (5). Plasmas generate thermal energy (heat) when heavy particle temperatures equilibrate with electron temperature but are considered "nonthermal" when the cooling of ions and uncharged molecules is more effective than the energy transfer from electrons to gas (5). Nonthermal or "cold" plasmas produce a variety of shortlived and long-lived reactive components, including charged particles and UV radiation, without significantly raising temperature (25). Nonthermal plasmas (NTPs) are applied extensively in materials science to modify the properties of carbon-based materials but have also shown promise for applications in biology and med-

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Section: Discussionmentioning

confidence: 72%

mentioning

confidence: 99%

Nonthermal Atmospheric Plasma Rapidly Disinfects Multidrug-Resistant Microbes by Inducing Cell Surface Damage

Kvam

Davis

Mondello

et al. 2012

Antimicrob Agents Chemother

160

111

View full text Add to dashboard Cite

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“…49 As in the case of hydrogen plasmas, the processing conditions for exposure of graphene to an oxygen plasma must be carefully controlled to avoid damage to the carbon lattice. In fact, attempts to measure the oxidation of graphite by an oxygen plasma have found that plasmas can etch graphite even at low exposure levels, creating single-atom vacancies and nanometer-sized pits, 50–51 while additional exposure induces the formation of micro-pores. 52 This potential for irreversible lattice damage in plasma-based oxidation is enhanced by the presence of higher energy ions such as O 2 + that can sputter carbonaceous material.…”

Section: Atomic Oxygen On Graphenementioning

confidence: 99%

Atomic Covalent Functionalization of Graphene

2012

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Conspectus Although graphene’s physical structure is a single atom thick, two-dimensional, hexagonal crystal of sp2 bonded carbon, this simple description belies the myriad interesting and complex physical properties attributed to this fascinating material. Because of its unusual electronic structure and superlative properties, graphene serves as a leading candidate for many next generation technologies including high frequency electronics, broadband photodetectors, biological and gas sensors, and transparent conductive coatings. Despite this promise, researchers could apply graphene more routinely in real-world technologies if they could chemically adjust graphene’s electronic properties. For example, the covalent modification of graphene to create a band gap comparable to silicon (~1 eV) would enable its use in digital electronics, and larger band gaps would provide new opportunities for graphene-based photonics. Towards this end, researchers have focused considerable effort on the chemical functionalization of graphene. Due to its high thermodynamic stability and chemical inertness, new methods and techniques are required to create covalent bonds without promoting undesirable side reactions or irreversible damage to the underlying carbon lattice. In this Account, we review and discuss recent theoretical and experimental work studying covalent modifications to graphene using gas phase atomic radicals. Atomic radicals have sufficient energy to overcome the kinetic and thermodynamic barriers associated with covalent reactions on the basal plane of graphene but lack the energy required to break the C-C sigma bonds that would destroy the carbon lattice. Furthermore, because they are atomic species, radicals substantially reduce the likelihood of unwanted side reactions that confound other covalent chemistries. Overall, these methods based on atomic radicals show promise for the homogeneous functionalization of graphene and the production of new classes of two-dimensional materials with fundamentally different electronic and physical properties. Specifically, we focus on recent studies of the addition of atomic hydrogen, fluorine, and oxygen to the basal plane of graphene. In each of these reactions a high energy, activating step initiates the process, breaking the local π structure and distorting the surrounding lattice. Scanning tunneling microscopy experiments reveal that substrate mediated interactions often dominate when the initial binding event occurs. We then compare these substrate effects with the results of theoretical studies that typically assume a vacuum environment. As the surface coverage increases, clusters often form around the initial distortion, and the stoichiometric composition of the saturated end product depends strongly on both the substrate and reactant species. In addition to these chemical and structural observations, we review how covalent modification can extend the range of physical properties that are achievable in two-dimensional materials.

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“…Up to now, various etching techniques including hyperthermal treatment by air or molecular oxygen, [19][20][21][22] ion bombardment, 23,24 oxygen plasma, [25][26][27][28][29][30] and wet chemical and electrochemical approaches 31 have been developed for this purpose. However, additional defects could be simultaneously introduced during the etching 25,26 due to the fast and vigorous interaction between carbon and these reactive species.…”

Section: Introductionmentioning

confidence: 99%

Identification of structural defects in graphitic materials by gas-phase anisotropic etching

Yang

Shi

et al. 2012

Nanoscale

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We developed a method of identifying the structural defects in graphitic materials by an anisotropic etching technique. Intrinsic and oxygen- or argon- plasma induced artificial defects' density and domain size can be obtained easily and precisely. It was inferred, through our investigations, that the grade ZYA highly oriented pyrolytic graphite (HOPG) sample has a better crystal quality, with a lower defect density, while the Kish graphite has a larger grain size and higher defect density. Defect types and lattice orientations can also be extracted by this technique. Furthermore, this method could apply to various graphitic materials including graphene.

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A comparison between physically and chemically driven etching in the oxidation of graphite surfaces

Cited by 40 publications

References 42 publications

Nonthermal Atmospheric Plasma Rapidly Disinfects Multidrug-Resistant Microbes by Inducing Cell Surface Damage

Nonthermal Atmospheric Plasma Rapidly Disinfects Multidrug-Resistant Microbes by Inducing Cell Surface Damage

Atomic Covalent Functionalization of Graphene

Identification of structural defects in graphitic materials by gas-phase anisotropic etching

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