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This paper presents a comprehensive assessment of historical (1990–2010) global anthropogenic particulate matter (PM) emissions including the consistent and harmonized calculation of mass-based size distribution (PM1, PM2. 5, PM10), as well as primary carbonaceous aerosols including black carbon (BC) and organic carbon (OC). The estimates were developed with the integrated assessment model GAINS, where source- and region-specific technology characteristics are explicitly included. This assessment includes a number of previously unaccounted or often misallocated emission sources, i.e. kerosene lamps, gas flaring, diesel generators, refuse burning; some of them were reported in the past for selected regions or in the context of a particular pollutant or sector but not included as part of a total estimate. Spatially, emissions were calculated for 172 source regions (as well as international shipping), presented for 25 global regions, and allocated to 0.5°  ×  0.5° longitude–latitude grids. No independent estimates of emissions from forest fires and savannah burning are provided and neither windblown dust nor unpaved roads emissions are included. We estimate that global emissions of PM have not changed significantly between 1990 and 2010, showing a strong decoupling from the global increase in energy consumption and, consequently, CO2 emissions, but there are significantly different regional trends, with a particularly strong increase in East Asia and Africa and a strong decline in Europe, North America, and the Pacific region. This in turn resulted in important changes in the spatial pattern of PM burden, e.g. European, North American, and Pacific contributions to global emissions dropped from nearly 30 % in 1990 to well below 15 % in 2010, while Asia's contribution grew from just over 50 % to nearly two-thirds of the global total in 2010. For all PM species considered, Asian sources represented over 60 % of the global anthropogenic total, and residential combustion was the most important sector, contributing about 60 % for BC and OC, 45 % for PM2. 5, and less than 40 % for PM10, where large combustion sources and industrial processes are equally important. Global anthropogenic emissions of BC were estimated at about 6.6 and 7.2 Tg in 2000 and 2010, respectively, and represent about 15 % of PM2. 5 but for some sources reach nearly 50 %, i.e. for the transport sector. Our global BC numbers are higher than previously published owing primarily to the inclusion of new sources. This PM estimate fills the gap in emission data and emission source characterization required in air quality and climate modelling studies and health impact assessments at a regional and global level, as it includes both carbonaceous and non-carbonaceous constituents of primary particulate matter emissions. The developed emission dataset has been used in several regional and global atmospheric transport and climate model simulations within the ECLIPSE (Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants) project and beyond, serves better parameterization of the global integrated assessment models with respect to representation of black carbon and organic carbon emissions, and built a basis for recently published global particulate number estimates.

There is interest in metal single atom catalysts due to their remarkable activity and stability. However, the synthesis of metal single atom catalysts remains somewhat ad hoc, with no universal strategy yet reported that allows their generic synthesis. Herein, we report a universal synthetic strategy that allows the synthesis of transition metal single atom catalysts containing Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Pt or combinations thereof. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and extended X-ray absorption fine structure spectroscopy confirm that the transition metal atoms are uniformly dispersed over a carbon black support. The introduced synthetic method allows the production of carbon-supported metal single atom catalysts in large quantities (>1 kg scale) with high metal loadings. A Ni single atom catalyst exhibits outstanding activity for electrochemical reduction of carbon dioxide to carbon monoxide, achieving a 98.9% Faradaic efficiency at -1.2 V.

Abstract Single-atom catalysts have been widely investigated for several electrocatalytic reactions except electrochemical alcohol oxidation. Herein, we synthesize atomically dispersed platinum on ruthenium oxide (Pt 1 /RuO 2 ) using a simple impregnation-adsorption method. We find that Pt 1 /RuO 2 has good electrocatalytic activity towards methanol oxidation in an alkaline media with a mass activity that is 15.3-times higher than that of commercial Pt/C (6766 vs. 441 mA mg ‒1 Pt ). In contrast, single atom Pt on carbon black is inert. Further, the mass activity of Pt 1 /RuO 2 is superior to that of most Pt-based catalysts previously developed. Moreover, Pt 1 /RuO 2 has a high tolerance towards CO poisoning, resulting in excellent catalytic stability. Ab initio simulations and experiments reveal that the presence of Pt‒O 3f (3-fold coordinatively bonded O)‒Ru cus (coordinatively unsaturated Ru) bonds with the undercoordinated bridging O in Pt 1 /RuO 2 favors the electrochemical dehydrogenation of methanol with lower energy barriers and onset potential than those encountered for Pt‒C and Pt‒Ru.

Most bulk-scale graphene is produced by a top-down approach, exfoliating graphite, which often requires large amounts of solvent with high-energy mixing, shearing, sonication or electrochemical treatment . Although chemical oxidation of graphite to graphene oxide promotes exfoliation, it requires harsh oxidants and leaves the graphene with a defective perforated structure after the subsequent reduction step . Bottom-up synthesis of high-quality graphene is often restricted to ultrasmall amounts if performed by chemical vapour deposition or advanced synthetic organic methods, or it provides a defect-ridden structure if carried out in bulk solution . Here we show that flash Joule heating of inexpensive carbon sources-such as coal, petroleum coke, biochar, carbon black, discarded food, rubber tyres and mixed plastic waste-can afford gram-scale quantities of graphene in less than one second. The product, named flash graphene (FG) after the process used to produce it, shows turbostratic arrangement (that is, little order) between the stacked graphene layers. FG synthesis uses no furnace and no solvents or reactive gases. Yields depend on the carbon content of the source; when using a high-carbon source, such as carbon black, anthracitic coal or calcined coke, yields can range from 80 to 90 per cent with carbon purity greater than 99 per cent. No purification steps are necessary. Raman spectroscopy analysis shows a low-intensity or absent D band for FG, indicating that FG has among the lowest defect concentrations reported so far for graphene, and confirms the turbostratic stacking of FG, which is clearly distinguished from turbostratic graphite. The disordered orientation of FG layers facilitates its rapid exfoliation upon mixing during composite formation. The electric energy cost for FG synthesis is only about 7.2 kilojoules per gram, which could render FG suitable for use in bulk composites of plastic, metals, plywood, concrete and other building materials.

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm at 80 °C with a low platinum loading of 0.09 mg cm , corresponding to a platinum utilization of 0.13 g kW in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

Electrochemical oxygen reduction to hydrogen peroxide (H O ) in acidic media, especially in proton exchange membrane (PEM) electrode assembly reactors, suffers from low selectivity and the lack of low-cost catalysts. Here we present a cation-regulated interfacial engineering approach to promote the H O selectivity (over 80%) under industrial-relevant generation rates (over 400 mA cm ) in strong acidic media using just carbon black catalyst and a small number of alkali metal cations, representing a 25-fold improvement compared to that without cation additives. Our density functional theory simulation suggests a \"shielding effect\" of alkali metal cations which squeeze away the catalyst/electrolyte interfacial protons and thus prevent further reduction of generated H O to water. A double-PEM solid electrolyte reactor was further developed to realize a continuous, selective (∼90%) and stable (over 500 hours) generation of H O via implementing this cation effect for practical applications.

Black carbon (BC) aerosol is the strongest sunlight-absorbing aerosol, and its optical properties are fundamental to radiative forcing estimations and retrievals of its size and concentration. BC particles exist as aggregate structures with small monomers and are widely represented by the idealized fractal aggregate model. In reality, BC particles possess complex and nonideal minor structures besides the overall aggregate structure, altering their optical properties in unforeseen ways. This study introduces the parameter “volume variation” to quantify and unify different minor structures and develops an empirical relationship to account for their effects on BC optical properties from those of ideal aggregates. Minor structures considered are as follows: the polydispersity of monomer size, the irregularity and coating of the individual monomer, and necking and overlapping among monomers. The discrete dipole approximation is used to calculate the optical properties of aggregates with these minor structures. Minor structures result in scattering cross-section enhancement slightly more than that of absorption cross section, and their effects on the angle-dependent phase matrix as well as asymmetry factor are negligible. As expected, the effects become weaker with the increase in wavelength. Our results suggest that a correction ratio of 1.05 is necessary to account for the mass or volume normalized absorption and scattering of nonideal aggregates in comparison to ideal ones, which also applies to aggregates with multiple minor structures. In other words, the effects of minor structures are mainly contributed by their influence on particle volume/mass that cannot be ignored, and a relative difference of approximately 5 % is noticed after removing the volume effects. Thus, accurate knowledge and evaluation of BC volume/mass are more important than those of the minor structures themselves. Most importantly, the simulations of optical properties of nonideal aggregates are greatly simplified by applying the empirical relationship because they can be directly obtained from those of the corresponding ideal aggregates, a volume/mass difference parameter, and the correction factor, i.e., 1.05, not the detailed minor structure information. We expect this convenient treatment to find wide applications for the accounting for the effects of nonideal minor structures on BC optical properties.

Based on the high-resolution measurement of black carbon (BC) at the Qomolangma (Mt. Everest) Station (QOMS, 28.36∘ N, 86.95∘ E, 4276 m a.s.l.) from 15 May 2015 to 31 May 2017, we investigated the seasonal and diurnal variations in BC and its potential source regions. Both monthly and daily mean BC concentrations reached the highest values in the pre-monsoon season and the lowest values in the monsoon season. The highest monthly and daily mean BC concentrations were at least 1 order of magnitude higher than the lowest concentrations. For the diurnal variation, the BC concentrations remained significantly high from late at night to morning in the pre-monsoon season. Meanwhile, the westerly winds prevailed during this period, implying the potential for pollutants to be transported across the Himalayas from long-distance sources to QOMS along the valley. In the monsoon season, the BC concentrations remained low but peaked in the morning and at noon, which might be caused by local emissions from cooking. By analyzing the simulation results from the backward trajectories of air masses and the fire spot distribution from the MODIS data, we found that the seasonal cycle of BC was significantly influenced by the atmospheric circulation and combustion intensity in the Mt. Everest region. The transport mechanisms of BC were further revealed using a WRF-Chem simulation during severe pollution episodes. For the pollution event in the monsoon season, BC aerosols in southern Asia were uplifted and transported to the Mt. Everest region by the southerly winds in the upper atmosphere. However, for the events in the pre-monsoon season, BC from northern India was transported and concentrated on the southern slope of the Himalayas by the northwesterly winds in the lower atmosphere and then transported across the Himalayas by the mountain-valley wind. A relatively smaller amount of BC from northwestern India and central Asia was transported to the Mt. Everest region by the westerly winds in the upper atmosphere.

Black carbon (BC) has been identified to play a critical role in aerosol–planetary boundary layer (PBL) interaction and further deterioration of near-surface air pollution in megacities, which has been referred to as the “dome effect”. However, the impacts of key factors that influence this effect, such as the vertical distribution and aging processes of BC, as well as the underlying land surface, have not been quantitatively explored yet. Here, based on available in situ measurements of meteorology and atmospheric aerosols together with the meteorology–chemistry online coupled model WRF-Chem, we conduct a set of parallel simulations to quantify the roles of these factors in influencing the BC dome effect and surface haze pollution. Furthermore, we discuss the main implications of the results to air pollution mitigation in China. We found that the impact of BC on the PBL is very sensitive to the altitude of aerosol layer. The upper-level BC, especially that near the capping inversion, is more essential in suppressing the PBL height and weakening the turbulent mixing. The dome effect of BC tends to be significantly intensified as BC mixed with scattering aerosols during winter haze events, resulting in a decrease in PBL height by more than 15 %. In addition, the dome effect is more substantial (up to 15 %) in rural areas than that in the urban areas with the same BC loading, indicating an unexpected regional impact of such an effect to air quality in countryside. This study indicates that China's regional air pollution would greatly benefit from BC emission reductions, especially those from elevated sources from chimneys and also domestic combustion in rural areas, through weakening the aerosol–boundary layer interactions that are triggered by BC.

Nanotechnology is an emerging field of science. The base of nanotechnology is nanoparticles. The size of nanoparticles ranges from 1 to 100 nm. The nanoparticles are classified into different classes such as inorganic nanoparticles, organic nanoparticles, ceramic nanoparticles and carbon base nanoparticles. The inorganic nanoparticles are further classified into metal nanoparticles and metal oxide nanoparticles.similarly carbon base nanoparticles classified into Fullerene, Carbon nanotubes, Graphene, Carbon nanofiber and carbon black Nanoparticles are also classified on the basis of dimension such as one dimension nanoparticles, two-dimension nanoparticles and three-dimension nanoparticles. The nanoparticles are synthesized by using two approaches like top-down approach and bottom-up approach. In this review chemical, physical and green synthesis of nanoparticles is reported. The synthesized nanoparticles are synthesized using different qualitative and quantitative techniques. The Qualitative techniques include Fourier Transform Infrared Spectroscopy (FT-IR), UV-Vis spectrophotometry, Scanning electron microscope (SEM), X.ray diffraction (XRD) and Atomic Force Microscopy (AFM). The Quantitative techniques include Transmission Electron Microscopy (TEM), Annular Dark-Field Imaging (HAADF) and Intracranial pressure (ICP). The nanoparticles have different application which is reported in this review.