Inception of Carbonaceous Nanostructures via Hydrogen-Abstraction Phenylacetylene-Addition Mechanism

Abstract

Sufficient experimental evidence has suggested that polycyclic aromatic hydrocarbons are the building blocks of carbonaceous nanostructures in combustion and circumstellar envelops of carbon-rich stars, but their fundamental formation mechanisms remain elusive. By exploring the reaction kinetics of phenylacetylene with 1-naphthyl/4-phenanthryl radicals, we provide compelling theoretical and experimental evidence for a novel and self-consistent hydrogen-abstraction phenylacetyleneaddition (HAPaA) mechanism. HAPaA operates efficiently at both low and high temperatures, leading to the formation, expansion, and nucleation of peri-condensed aromatic hydrocarbons (PCAHs), which are otherwise difficult to synthesis via traditional hydrogen-abstraction acetylene/vinylacetylene-addition pathways. The HAPaA mechanism can be generalized to other α-alkynyl PCAHs and thus provides an alternative covalent bond bridge for PCAH combination via an acetylene linker. The proposed HAPaA mechanism may contribute toward a comprehensive understanding of soot formation, carbonaceous nanomaterials synthesis, and the origin and evolution of carbon in our galaxy.

Probing combustion and catalysis intermediates by synchrotron vacuum ultraviolet photoionization molecular-beam mass spectrometry: recent progress and future opportunities

“…A notable progress is the very recent works reported by Jin and co-workers. 66,67 In the regard of PAH formation, they proposed a radical efficient PAH growth pathway named as CBAC, wherein the propargyl radical reacts with butadiyne to form larger radicals containing newly fused aromatic rings. Fig.…”

“…For the mechanism of soot inception, they reported the theoretical and experimental identification of key reaction products including phenyl-acenaphthylene, acenaphthylene, phenyl-pyrene, and pyrene in 1-naphthyl/phenyl-acetylene and 4-phenanthryl/phenylacetylene reaction systems, elucidating the self-consistent hydrogen-abstraction phenylacetylene-addition (HAPaA) mechanism. 67…”