The low-temperature oxidation products including cyclic olefins, cyclic ethers and highly oxygenated intermediates including ketohydroperoxide (KHP), keto-dihydroperoxide (KDHP), olefinic hydroperoxides (OHP), ketone structure products were observed by the MB-VUV-PI-TOFMS at 1-3 atm pressure. In particular, we want to emphasize that the developed MB-VUV-PI-TOFMS can carry out insitu analysis and detect products at higher than atmospheric pressure, which is closer to the state of the actual combustion system.

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Highly oxygenated intermediates play an important role in the low‐temperature oxidation of fuels. In this study, a molecular beam sampling vacuum ultraviolet photoionization time‐of‐flight mass spectrometer (MB‐VUV‐PI‐TOFMS) is used to observe the low‐temperature oxidation products, especially highly oxygenated intermediates like ketohydroperoxide (KHP), keto‐dihydroperoxide (KDHP), olefinic hydroperoxides (OHP) and dione structure products. More information can be found in the Full Paper by S. Chen, J. Chen, Z. Tang, et al. (DOI: 10.1002/chem.202103546).

At present, the reactivity of cyclic alkanes is estimated by comparison with acyclic hydrocarbons. Due to the difference in the structure of cycloalkanes and acycloalkanes, the thermodynamic data obtained by analogy are not applicable. In this study, a molecular beam sampling vacuum ultraviolet photoionization time‐of‐flight mass spectrometer (MB‐VUV‐PI‐TOFMS) was applied to study the low‐temperature oxidation of cyclopentane (CPT) at a total pressure range from 1–3 atm and low‐temperature range between 500 and 800 K. Low‐temperature reaction products including cyclic olefins, cyclic ethers, and highly oxygenated intermediates (e. g., ketohydroperoxide KHP, keto‐dihydroperoxide KDHP, olefinic hydroperoxides OHP and ketone structure products) were observed. Further investigation of the oxidation of CPT – electronic structure calculations – were carried out at the UCCSD(T)‐F12a/aug‐cc‐pVDZ//B3LYP/6‐31+ G(d,p) level to explore the reactivity of O2 molecules adding sequentially to cyclopentyl radicals. Experimental and theoretical observations showed that the dominant product channel in the reaction of CPT radicals with O2 is HO2 elimination yielding cyclopentene. The pathways of second and third O2 addition – the dissociation of hydroperoxide – were further confirmed. The results of this study will develop the low‐temperature oxidation mechanism of CPT, which can be used for future research on accurately simulating the combustion process of CPT.

Nitrogen-doped carbon materials demonstrate high performance as electrodes in fuel cells and higher oxygen reduction reactivity than traditional Pt-based electrodes. However, the formation process of nitrogen-doped carbon materials has long been a mystery. In this study, the formation mechanism of nitrogen-doped carbon materials from polyaniline (PANI) pyrolysis was studied by the combination of in situ pyrolysis vacuum ultraviolet photoionization time-of-flight mass spectrometry (Py-VUVPI-TOF MS) and substrate-enhanced, laser-induced acoustic desorption source time-of-flight mass spectrometry (SE-LIAD-TOF MS). The initial pyrolysis species, including free radicals and intermediates, were investigated via in situ Py-VUVPI-TOF MS during the temperature-programmed desorption process (within tens of microseconds). The pyrolysis residues were collected and further investigated via SE-LIAD-TOF MS, revealing the product information of the initial pyrolysis products. The results show that the edge doping of carbon materials depends on free radical reactions rather than the direct substitution of carbon atoms by nitrogen atoms. Meanwhile, pyrrole nitrogen and pyridine nitrogen are formed by the free radical cyclization reaction and the amino aromatization reaction at the initial stage of pyrolysis, while the formation of graphitic nitrogen depends on the further polymerization reaction of pyrrole nitrogen and pyridine nitrogen.