Probing Distinct Fullerene Formation Processes from Carbon Precursors of Different Sizes and Structures

Abstract

Fullerenes, cage-structured carbon allotropes, have been the subject of extensive research as new materials for diverse purposes. Yet, their formation process is still not clearly understood at the molecular level. In this study, we performed laser desorption ionization-ion mobility-mass spectrometry (LDI-IM-MS) of carbon substrates possessing different molecular sizes and structures to understand the formation process of fullerene. Our observations show that the formation process is strongly dependent on the size of the precursor used, with small precursors yielding small fullerenes and large graphitic precursors generally yielding larger fullerenes. These results clearly demonstrate that fullerene formation can proceed via both bottom-up and top-down processes, with the latter being favored for large precursors and more efficient at forming fullerenes. Furthermore, we observed that specific structures of carbon precursors could additionally affect the relative abundance of C60 fullerene. Overall, this study provides an advanced understanding of the mechanistic details underlying the formation processes of fullerene.

Piecing Together Large Polycyclic Aromatic Hydrocarbons and Fullerenes: A Combined ChemTEM Imaging and MALDI-ToF Mass Spectrometry Approach

“…The fact that C 60 forms only in the case of coronene and perylene is noteworthy, and suggests a dependence on the structure of the initial PAH, or of the oligomers that are formed. An analogous result was obtained for triphenylene by Han et al (2016) though their mechanistic interpretation differs and is focused on the "zipper" mechanism involving the rapid, concerted formation of 12 pentagon rings in one step between two overlying PAHs as advanced by Homann and co-authors. The "zipper" mechanism is based principally on topological considerations and mass spectrometric observations of hydrocarbon rich, sooting flames (Baum et al, 1992;Ahrens et al, 1994).…”

“…For generation of large PAHs on non-metallic surfaces, approaches include thermal fusion of coronene and pentacene (Ishii et al, 2011), soft X-ray irradiation of pentacene (Heya et al, 2020), and oligomerization of dehydrogenated PAHs deposited as cations from the gas phase (Weippert et al, 2020). In respect of fullerene formation, this route is supported by experimental observation of C 60 formation during the pyrolysis of PAHs (Taylor et al, 1993;Osterodt et al, 1996), laser pyrolysis of hydrocarbons (Ehbrecht et al, 1993;Armand et al, 1997) and laser desorption ionisation (LDI) of triphenylene in an experiment that combines LDI with ion-mobility mass spectrometry (Han et al, 2016). Gas-phase formation of large PAHs includes conversion of ionic pyrene clusters under laser irradiation (Zhen et al, 2018), and pyrene-dicoronylene and hexabenzocoronene-anthracene equivalents (Zhen 2019;Zhen et al, 2019).…”

Direct Mass Spectrometric Analysis of Solid Coal Samples Using Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

“…)). Most likely, these carbon clusters were formed during the LDI process because of the presence of carbon-rich precursor molecules. , The m / z of these clusters were not used for further data evaluation because they were also detected in the blank analysis due to the usage of a pure graphite matrix and, hence, are removed from the sample analyses during blank correction. Nonetheless, these ions raise the question if the detected ionized molecules have their origin in the sample itself or if they were generated by the laser during the LDI event.…”

The Effect of the Polyaromatic Hydrocarbon in the Formation of Fullerenes

“…The current proposed fullerene growth models typically involve small carbon clusters growing into fullerenes. However, in very different and often conflicting ways, the “pentagon road”, “fullerene road”, and “ring coalescene” mechanisms usually propose that fullerenes are generated from larger structures, namely a “top‐down” mechanism. At the same time, a graphene‐to‐fullerene conversion was recently shown to be possible under certain conditions .…”