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Toward the pursuit of high-performance Ni 2+ /Co 2+ /Fe 3+relevant oxygen evolution reaction (OER) electrocatalysts, the modulation of local electronic structure of the active metal sites provides the fundamental motif, which could be achieved either through direct modifications of local chemical environment or interfacial interaction with a second metal substrate which possesses high electronegativity (typically noble metal Au). Herein, we report that the local electronic structure of Ni− Fe layered double hydroxide (LDH) could be favorably modulated through strong interfacial interactions with FeOOH nanoparticles (NPs). The biphasic and multiscale composites FeOOH/LDH demonstrated an increasingly pronounced synergy effect for OER catalysis when the average size of FeOOH NPs decreases from 18.0 to 2.0 nm. Particularly, the composite with average size of FeOOH NPs of 2.0 nm exhibited an overpotential of 174 mV at 10 mA cm −2 and a tafel slope of 27 mV dec −1 in 1.0 M KOH, outmatching all the noble and non-noble OER catalysts reported so far; it also operates smoothly in various stability tests. A mechanistic study based on XANES and EXAFS analysis, d.c. voltammetry and large amplitude Fourier Transformed a.c. voltammetry proved the presence of high-oxidation-state Fe (3+δ)+ sites with relatively short Fe (3+δ)+ −O bond from the highly unsaturated ultrafine FeOOH NPs which could reform the local electronic structure and favorably manipulate the electronic oxidation and thus electrocatalytic behaviors of the Ni 2+ species in the Ni−Fe LDH, hence leading to the easy formation, excellent OER activity, and extraordinary structural and catalytic stability. Our work puts an emphasis on the role of the solid−solid interfacial chemistry between a Ni−Fe LDH and a non-noble-metal component in engineering the local electronic structure of the active metal sites, which successfully pushed forward the catalytic activity of the well-studied Ni−Fe LDH far beyond its current limit in OER catalysis and opened up an avenue for rational design of OER electrocatalysts.

A low-pressure premixed toluene/O 2 /Ar flame with the equivalence ratio of 1.90 was investigated using tunable synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry. Combustion intermediates up to C 19 H 12 were identified by the measurements of the photoionization mass spectrum and photoionization efficiency spectrum. Mole fraction profiles of flame species were evaluated from the scan of burner position at photon energies near ionization thresholds. Furthermore, flame temperature was recorded by a Pt/Pt-13%Rh thermocouple. The comprehensive experimental data concerning the flame structure facilitate the discussion about the flame chemistry of toluene and other monocyclic aromatic fuels. Benzyl and benzene were found to be major primary intermediates of toluene degradation; and benzene is suggested to originate mainly from fuel degradation instead of radical recombination channels in fuel-rich monocyclic aromatic hydrocarbon flames. On the basis of the intermediate identification, comparison is made among the current mechanisms relevant to the formation of polycyclic aromatic hydrocarbons (PAHs). It is concluded that the molecular growth process in this flame is consistent with the synergy of the hydrogen-abstraction-carbon-addition (HACA) mechanism and the resonantly stabilized radical addition mechanism. In particular, the HACA mechanism can connect a great deal of aromatic intermediates observed in the present work and consequently explain the regular ring enlargement by consecutive addition of 2 or 4 carbon atoms, while the resonantly stabilized radical addition mechanism may have marked and sometimes predominant influences on the formation of many typical PAHs.

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Diethyl ether (DEE) has been recently suggested as a potential biofuel for compression-ignition engines that are known to be significantly controlled by low-temperature (LT) chemistry. However, the LT oxidation of DEE has not fully been understood in term of the formation of LT fuel-specific products. We have thus studied the oxidation of DEE by examining detailed profiles of its oxidation products under LT conditions (400-1100 K). To this end, we have used a dedicated experimental setup including a nearly-atmospheric jet-stirred reactor (JSR) coupled to online gas chromatography (GC). The experiments were complemented by measurements made with a JSR coupled to tunable synchrotron vacuum ultraviolet (SVUV) photoionization (PI) molecular-beam mass spectrometry (MBMS) for a cross-validation of the identification of important LT species. Experimental results indicate that DEE is very reactive; it starts to react around 425 K. DEE exhibits an unusual oxidation behavior with two negative temperature coefficient (NTC) zones in the JSR study. Because of this two-NTC observation, additional experiments were performed with a plug flow reactor (PFR) combined with electron ionization (EI)-MBMS, confirming this behavior in the two types of reactor. Moreover, about 20 oxidation species in C1-C4 range were detected with several intermediates containing 2-3 O-atoms. Acetic acid is found to peak at 525 K with a very large amount, suggesting that it is a key species in the early stage of DEE's LT oxidation. Possible DEE-consumption paths leading to acetic acid formation could play an important role in the oxidation mechanism of DEE. A new model is proposed based on the present experimental observations to include new primary LT reaction paths. The model reproduces the experimental phenomena quite well and enhances the understanding of the two-NTC-zone occurrence and of intermediates containing 2-3 O-atoms during the LT oxidation of DEE.

Combustion is one of the earliest developed human technologies and remains our primary source of energy, yet it embodies a complex suite of physical and chemical processes that are inadequately understood. Combustion chemistry involves both chemical thermodynamics and chemical kinetics, and experimental advances mostly depend on the development of combustion diagnostics, which effectively serve as the foundation of theoretical progress. The major objective of combustion diagnostics is to provide comprehensive product identification and concentration information of a flame species, which can be used to develop kinetic models for the simulation of practical combustion. However, conventional combustion diagnostic methods face difficult challenges in distinguishing isomeric species, detecting reactive radicals, obtaining real-time measurements, and so forth. Therefore, for deeper insight into combustion chemistry, a diagnostic method with high detection sensitivity, isomeric selectivity, and radical detectability is required. In this Account, we report recent applications of synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) in various areas of combustion chemistry research. The wide tunability of synchrotron photon energy can facilitate the selective identification of isomeric intermediates and the near-threshold detection of radicals (thus avoiding fragmentation interference). Moreover, the convenient combination of SVUV-PIMS with various laboratory-based combustion approaches demonstrates its universality in combustion studies. Recent experimental achievements have demonstrated the successful applications of this technique in premixed flames, pyrolysis in flow reactors, coflow diffusion flames, catalytic oxidation, plasma diagnostics, and analysis of polycyclic aromatic hydrocarbons (PAHs) and soot. More applications of SVUV-PIMS are expected in the near future, not only in combustion studies, but also in other research topics of chemistry such as analytical chemistry, photochemistry, biochemistry, and the like. In all applications, combustion intermediates, including isomers and radicals, can be distinguished unambiguously, extending our knowledge of intermediate pools and providing more precise targets for quantum chemical calculations of significant reaction channels. The observed mass range covers both small and large combustion products, such as PAHs with two to five carbonic rings. Such analyses present clues toward understanding the molecular growth process from fuel to PAHs and, consequently, soot in fuel-rich hydrocarbon flames. Furthermore, quantitative analyses of chemical structure are available in most applications. For example, one can acquire concentration profiles of flame species versus position in premixed and diffusion flames or versus temperature in pyrolysis and catalytic oxidation. The objectives of validating current kinetic models and developing new kinetic models are thus well served with SVUV-PIMS as an analytical tool in combustion research.

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Genomics has provided a detailed structural description of the cancer genome. Identifying oncogenic drivers that work primarily through dosage changes is a current challenge. Unrestrained proliferation is a critical hallmark of cancer. We constructed modular, barcoded libraries of human open reading frames (ORFs) and performed screens for proliferation regulators in multiple cell types. Approximately 10% of genes regulate proliferation, with most performing in an unexpectedly highly tissue-specific manner. Proliferation drivers in a given cell type showed specific enrichment in somatic copy number changes (SCNAs) from cognate tumors and helped predict aneuploidy patterns in those tumors, implying that tissue-type-specific genetic network architectures underlie SCNA and driver selection in different cancers. In vivo screening confirmed these results. We report a substantial contribution to the catalog of SCNA-associated cancer drivers, identifying 147 amplified and 107 deleted genes as potential drivers, and derive insights about the genetic network architecture of aneuploidy in tumors.