Formation of Sublimable Nanographene Oxides by Reacting Coronene Films with Atomic Oxygen

Abstract

We have studied the oxidation of multilayer thin films of coronene (C 24 H 12 ) on graphite under UHV conditions. Coronene films were grown by low-energy cluster ion beam deposition (LECBD, C 24 H 12 + , E kin < 6 eV) and subsequently oxidized by exposing them to a beam of nearthermal atomic oxygen at room temperature. Mass spectra recorded during sublimation of the oxidized coronene films reveal a distribution of emitted species, C 24 H 12 O n (n ≤ 7), which we assign as coronene epoxides. From the fragmentation pattern we infer that primarily rim epoxides are formed, which exhibit a higher stability than core epoxides according to DFT calculations. In addition to epoxides, XPS indicates that other oxidic functional groups, such as ethers, are also formed in smaller relative amounts as nonsublimable species. The overall yield for the thermal desorption of intact coronene oxides can be up to 7% of the deposited coronene, sufficiently high such that this procedure could be useful as a source of monodispersed nanoscale graphene oxides (nano-GOs) for applications in nanotechnology.

Coronenes, Benzocoronenes and Beyond: Modern Aspects of Their Syntheses, Properties, and Applications

“…After the claim of its existence, [170] graphenes [171] and nanographenes scaffolds have been the center of vast scientific researches on their preparations, properties and applications. In that, nanographenes, including coronene and expanded coronenes, symbolizing the framework‐expanded polycyclic aromatic hydrocarbons (PAHs), [172–173] are particularly important, as they can be used to modulate the size and functionality of certain graphene architectures [174,175] …”

Comparative Study of Direct and Graphite-Mediated Oxidation of Large PAHs

“…We have recently probed the oxidation of thin coronene (C 24 H 12 ) films using mass-resolved temperature-programmed desorption (TPD) to characterize the volatile oxidic products generated under these conditions. 16,17 Interestingly, we observed significant amounts of intactly desorbing coronene oxides.…”

“…38 All of these have the same intact coronene skeleton but terminating functionalities that differ significantly from the unprecedented rim-epoxy derivatives, which we found upon treating thick coronene films to thermal energy oxygen atoms at the solid−gas interface. 16 Similarly, only a limited number of oxidized derivatives of the PAHs studied here have previously been accessed in condensed phase synthesis. A symmetric alkoxy derivative of HBC has been reported 42 based on the assembly of alkoxy-substituted precursors.…”

“…A thick multilayer coronene film was deposited onto the basal plane of HOPG and subsequently treated with a perpendicularly incident, near-thermal-energy effusive beam of oxygen atoms from a plasma source. 16 This led to intactly desorbable coronene epoxides and, for higher oxidation degrees, eventually coronene ethersas assigned by combining mass-resolved temperatureprogrammed desorption (TPD) with X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. We rationalized this reaction outcome as being analogous to the O-atom functionalization of the HOPG 18,19 basal plane, which also showed epoxides as the major products at low exposures while ethers appeared for higher oxygen atom loads.…”

Modifiye Hummers Yöntemi ile Elde Edilen Grafen Oksit Sentezleri İçin: Kısım 2, X Işını Fotoelektron Spektroskopisi Analizi

“…Ayrıca C1s spektrumunun çekirdek seviyesinde farklı deformasyonlardan dolayı farklı enerji kayma değerleri de rapor edilmiştir. Bu yüzden bazı çalışmalarda, 284,5 eV den daha düşük bağ enerjisi değerlerinde de nispi yoğunlukları çok olmasa bile kusurlu sp 3 hibridize karbon atomlarına atfedilen sinyallerin (C-C) ortaya çıktığı da bildirilmiştir[23][24][25].Kimyasal oksidasyondan sonra grafit bazal düzleminde oluşan fonksiyonel gruplardan; karboksilik (O-C=O) ve karbonil (C=O) grupları esas olarak bazal düzlemin kenarlarına bağlandığı, fenolik hidroksil (-OH) ve epoksi (C-O-C) gruplarının ise iç kısımlarda yer aldığı yaygın olarak kabul edilmektedir[26].Bu çalışmada yapılan C1s spektrumuna ait uygun eğri, doğrusal olmayan algoritma kullanılarak Gaussian ve Lorentzian dağılımlarıyla gerçekleştirilmiştir. Bu dağılımlarda en iyi korelasyon katsayısı ve eğri, Lorentzian dağılımıyla elde edilmiştir.…”