Nighttime reactions of a series of unsaturated alcohols with NO•: Kinetics, products and mechanisms study.

Unsaturated alcohols are a class of Biogenic volatile organic compounds (BVOCs) emitted in large quantities by plants when damaged or under adverse environmental conditions, and studies on their atmospheric degradation at night are still lacking. We used chamber experiments to study the gas-phase reactions of three unsaturated alcohols, E-2-penten-1-ol, Z-2-hexen-1-ol and Z-3-hepten-1-ol, with NO radicals (NO•) during the night. The rate constants of these reactions were (11.

A comprehensive observation on the pollution characteristics of peroxyacetyl nitrate (PAN) in Beijing, China.

Peroxyacetyl nitrate (PAN) is a typical secondary photochemical product in the atmospheric environment with significant adverse effects on human health and plant growth. In this study, PAN and other pollutants, as well as meteorological conditions were observed intensively from August to September in 2022 at a typical urban sampling site in Beijing, China. The mean and maximum PAN concentrations during the observation period were 1.

Characterization of products formed from the oxidation of toluene and m-xylene with varying NO and OH exposure.

Aromatic volatile organic compounds (VOCs) are an important precursor of secondary organic aerosol (SOA) in the urban environment. SOA formed from the oxidation of anthropogenic VOCs can be substantially more abundant than biogenic SOA and has been shown to account for a significant fraction of fine particulate matter in urban areas. A potential aerosol mass (PAM) chamber was used to investigate the oxidised products from the photo-oxidation of m-xylene and toluene.

Atmospheric chemistry of nitrous acid and its effects on hydroxyl radical and ozone at the urban area of Beijing in early spring 2021.

The atmospheric chemistry of nitrous acid (HONO) has received extensive attention because of its significant contribution to hydroxyl (OH) radicals. Heterogeneous reaction of NO is an important HONO source, and its reaction mechanism is affected by many factors, such as concentration of gaseous NO, surface adsorbed water, relative humidity and temperature. Although laboratory studies have confirmed the effect of temperature on heterogeneous reaction of NO, there are few field observations reporting about it.

Partially Nitrided Ni Nanoclusters Achieve Energy-Efficient Electrocatalytic CO Reduction to CO at Ultralow Overpotential.

Electrocatalytic CO reduction reaction (CO RR) offers a promising strategy to lower CO emission while producing value-added chemicals. A great challenge facing CO RR is how to improve energy efficiency by reducing overpotentials. Herein, partially nitrided Ni nanoclusters (NiN ) immobilized on N-doped carbon nanotubes (NCNT) for CO RR are reported, which achieves the lowest onset overpotential of 16 mV for CO -to-CO and the highest cathode energy efficiency of 86.

Atmospheric oxidizing capacity in autumn Beijing: Analysis of the O and PM episodes based on observation-based model.

Atmospheric oxidizing capacity (AOC) is the fundamental driving factors of chemistry process (e.g., the formation of ozone (O) and secondary organic aerosols (SOA)) in the troposphere.

Sources of ambient non-methane hydrocarbon compounds and their impacts on O formation during autumn, Beijing.

The field observation of 54 non-methane hydrocarbon compounds (NMHCs) was conducted from September 1 to October 20 in 2020 during autumn in Haidian District, Beijing. The mean concentration of total NMHCs was 29.81 ± 11.

Formation mechanisms of nitrous acid (HONO) during the haze and non-haze periods in Beijing, China.

As an important precursor of hydroxyl radical (OH), nitrous acid (HONO) plays a significant role in atmospheric chemistry. Here, an observation of HONO and relevant air pollutants in an urban site of Beijing from 14 to 28 April, 2017 was performed. Two distinct peaks of HONO concentrations occurred during the observation.

Effect of Different Combustion Processes on Atmospheric Nitrous Acid Formation Mechanisms: A Winter Comparative Observation in Urban, Suburban and Rural Areas of the North China Plain.

Atmospheric nitrous acid (HONO) is a dominant precursor of hydroxyl (OH) radicals, and its formation mechanisms are still controversial. Few studies have simultaneously explored effects of different combustion processes on HONO sources. Hereby, synchronous HONO measurement in urban (BJ), suburban (XH) and rural (DBT) areas with different combustion processes is performed in the North China Plain in winter.

Amide-bridged conjugated organic polymers: efficient metal-free catalysts for visible-light-driven CO reduction with HO to CO.

The visible-light-driven photoreduction of CO to value-added chemicals over metal-free photocatalysts without sacrificial reagents is very interesting, but challenging. Herein, we present amide-bridged conjugated organic polymers (amide-COPs) prepared self-condensation of amino nitriles in combination with hydrolysis, for the photoreduction of CO with HO without any photosensitizers or sacrificial reagents under visible light irradiation. These catalysts can afford CO as the sole carbonaceous product without H generation.

Heterogeneous Formation of HONO Catalyzed by CO.

Gas-phase nitrous acid (HONO) is a major precursor of hydroxyl radicals that dominate atmospheric oxidizing capacity. Nevertheless, pathways of HONO formation remain to be explored. This study unveiled an important CO-catalysis mechanism of HONO formation, using Born-Oppenheimer molecular dynamics simulations and free-energy samplings.

Photocatalytic Oxidation of SO by TiO: Aerosol Formation and the Key Role of Gaseous Reactive Oxygen Species.

Photocatalytic materials are proved to effectively eliminate gaseous pollutants and are widely used in the environment. However, as one of the rare experiments focusing on their influence on secondary aerosol formation generated in the gas phase (SA), our study demonstrated the high-yield SA formation in the photocatalysis process. In this study, the photodegradation of SO by TiO under various relative humidity (RH) conditions was deeply explored with multiple methods.

Reaction mechanism and kinetics of Criegee intermediate and hydroperoxymethyl formate.

The reaction mechanism and kinetics of the simplest Criegee intermediate CHOO reaction with hydroperoxymethyl formate (HPMF) was investigated at high-level quantum chemistry calculations. HPMF has two reactive functional groups, -C(O)OH and -OOH. The calculated results of thermodynamic data and rate constants indicated that the insertion reactions of CHOO with -OOH group of HPMF were more favorable than the reactions of CHOO with -C(O)OH group.

Important Oxidants and Their Impact on the Environmental Effects of Aerosols.

Oxidants are central species in the atmosphere, where they not only determine secondary particle formation but also impact human health and climate change. In general, they are unstable, highly reactive, and recyclable and have been studied in field observations, laboratory studies, and model simulations. The most widely investigated oxidants, such as OH radicals, O, and Cl atom, HONO, NO, NO, and Criegee Intermediates (CIs) have attracted more attention recently.

Aerosol Promotes Peroxyacetyl Nitrate Formation During Winter in the North China Plain.

Peroxyacetyl nitrate (PAN) is an important indicator for photochemical pollution, formed similar to ozone in the photochemistry of certain volatile organic compounds (VOCs) in the presence of nitrogen oxides, and has displayed surprisingly high concentrations during wintertime that were better correlated to particulate rather than ozone concentrations, for which the reasons remained unknown. In this study, wintertime observations of PAN, VOCs, PM, HONO, and various trace gases were investigated to find the relationship between aerosols and wintertime PAN formation. Wintertime photochemical pollution was affirmed by the high PAN concentrations (average: 1.

Light absorption properties and potential sources of brown carbon in Fenwei Plain during winter 2018-2019.

A distinctive kind of organic carbon aerosol that could absorb ultraviolet-visible radiation is called brown carbon (BrC), which has an important positive influence on radiative budget and climate change. In this work, we reported the absorption properties and potential source of BrC based on a seven-wavelength aethalometer in the winter of 2018-2019 at an urban site of Sanmenxia in Fenwei Plain in central China. Specifically, the mean value of BrC absorption coefficient was 59.

Insights into air pollution chemistry and sulphate formation from nitrous acid (HONO) measurements during haze events in Beijing.

Wintertime urban air pollution in many global megacities is characterised by episodic rapid increase in particulate matter concentrations associated with elevated relative humidity - so-called haze episodes, which have become characteristic of cities such as Beijing. Atmospheric chemistry within haze combines gas- and condensed-phase chemical processes, leading to the growth in secondary species such as sulphate aerosols. Here, we integrate observations of reactive gas phase species (HONO, OH, NO) and time-resolved aerosol composition, to explore observational constraints on the mechanisms responsible for sulphate growth during the onset of haze events.

Seasonal characterization of aerosol composition and sources in a polluted city in Central China.

We characterized the aerosol composition and sources of particulate matter (PM) in Sanmenxia, a polluted city located in the Fen-Wei Plain region of Central China. The PM concentration decreased by 18% from 72 μg m in 2014 to 59 μg m in 2019. All chemical species presented pronounced seasonal variations, with their highest concentrations in winter due to enhanced emissions and the frequent stagnant meteorological conditions.

Different HONO Sources for Three Layers at the Urban Area of Beijing.

Gaseous nitrous acid (HONO) is a crucial precursor of the hydroxyl (OH) radical, which is a "detergent" in the atmosphere. Nowadays, HONO formation mechanisms at polluted urban areas are controversial, which restricts the understanding of atmospheric oxidative capacity and radical cycling. Herein, multiday vertical observation of HONO and NO was simultaneously performed at three heights at the urban area of Beijing for the first time.

Kinetic and mechanism studies of the ozonolysis of three unsaturated ketones.

Reaction rate constants and products of 1-octen-3-one, 3-octen-2-one and 4-hexen-3-one with ozone were studied in a 100-L fluorinated ethylene propylene (FEP) Teflon film bag using absolute rate method at 298 ± 1 K and atmospheric pressure. The rate constants were (1.09 ± 0.

Pollution characteristics and potential sources of nitrous acid (HONO) in early autumn 2018 of Beijing.

Nitrous Acid (HONO) is an important precursor of hydroxyl radical (OH) and has significant impacts on the formation of Ozone (O) and Secondary Organic Aerosol (SOA). The atmospheric concentrations of HONO were measured during early autumn in downtown, Beijing (China). This study investigated HONO pollution characteristics and potential sources during day and night.

Study on ozonolysis of asymmetric alkenes with matrix isolation and FT-IR spectroscopy.

O and alkenes are important reactants in the formation of SOA in the atmosphere. The intermediates and reaction mechanism of ozonation of alkene is an important topic in atmospheric chemistry. In this study, the low-temperature matrix isolation was used to capture the intermediates such as Primary ozonides (POZs), Criegee Intermediates (CIs), and Secondary ozonides (SOZs) generated from ozonation of 2-methyl-1-butene (2M1B) and 2-methyl-2-butene (2M2B).