Chemical composition and morphology altogether determine the fate of atmospheric particulate matter(PM) deposition and inhalation. Site-wise(#20 sites) and cumulative variations in chemical composition and morphology of PM5 in Delhi showed dominance of both spherical-granular particles and non-spherical- sharp edged, angular and flattened particles rich in elements like C, O, S, N, Al, Si, Cu, Ca, Na, Cl, Fe, Hg, Pb, Mo, etc. having potential health effects. #2650 individual particles analyzed for the morphological parameters like Aspect ratio(AR), Circularity factor(CIR), Surface Equivalent Radius(SER) and area. Cumulative AR(>70% of particles) and SER(>80% of particles) found dominant with values 1-1.60 and 0-0.50 μm, respectively showing dominance of non-spherical and fine-size particles in Delhi. MPPD Model used to study variations in deposition potential (Regional deposition, Lobar deposition, Mass deposition vs generation number and mass flux) of different PM sizes (PM0.4, PM1, PM2.5 and PM5) at different AR values which suggested that AR is an important input parameter of health models to get realistic and unbiased output health data. The study also shows higher coarse particles deposition in the head region affecting upper respiratory tract with their non-spherical shape whereas higher fine particles deposition in TB and pulmonary regions affecting inner parts of lungs.
Explicit control of the crystalline phases and morphology of semiconducting BiVO4 crystals has been successfully synthesized via microwave-hydrothermal condition (MW-HT) without requiring any template/surfactant, doping of metal ions, and altering pH of reaction solution. Unambiguously, the crystalline phase of BiVO4 crystal has transformed from tetragonal zircon type (tz) to monoclinic scheelite (m) via mixed-phase (m-tz) by altering microwave-irradiation time at fixed microwave-irradiation power (800 W) without changing any precursor concentrations throughout the reaction. X-ray diffraction and Rietveld refinement studies confirmed the phase transformation of BiVO4 crystals that occurs by controlling the irradiation time (10–22 min) and temperature (116–195 °C). The changes in VO43– tetrahedron bond strength and bond length attributed to phase transitions in BiVO4 crystals were corroborated by Raman spectra. Field emission scanning electron microscope revealed the sequential growth and rational morphological evolution of spherical-shaped zircon type tz-BiVO4 particles to preferentially oriented (010) and (110)-faceted decahedron-shaped scheelite m-BiVO4 crystals. The UV-reflectance and photoluminescence analyses revealed reduction in the optical bandgap and efficient charge separation with tunneling of excitons through interfaces, owing to phase transitions from tetragonal to monoclinic in BiVO4 crystals. High-resolution transmission electron microscopy images revealed the formation of heterojunctions between both the phases of BiVO4 crystals. The photocatalytic degradation of Rhodamine-B dye under natural sunlight showed maximum efficiency of 95% with highest rate kinetics (κavg = 0.0718/min) using mixed-phase BiVO4 (m:tz-60:40) crystals, whereas under simulated sunlight, monoclinic phase BiVO4 crystals showed high degradation efficiency of 87% with low rate kinetics (κavg= 0.0436/min) for 200 min. The free-radical trapping tests revealed that superoxide radical (•O2) and hydroxyl radical (•OH) are active radicals during photocatalysis. Significantly, the MW-HT synthesized mixed-phase BiVO4 retained photocatalytic activity and structural stability even after three cycles. These findings open possibilities for innovative design of highly efficient semiconductor photocatalyst for environmental remediation applications.
A sustainable utilization of resources with systematic development of society is an urgent need for human civilization. The effective utilization of non-renewable energy resources pursues collaborative socio-economic and environmental balancing. CO 2 conversion and utilization will be the alternative way forward for low-carbon chemical and energy industries. Additionally, a non-expensive and clean energy through hydrogen (H 2 ) is contemplated as one of the most reliable, hopeful, and next-generation green energy fuels. In the last few decades, extensive progress has focused on production of hydrogen, purification, storage, transportation, and conversion to energy. The consumption of fuel-based hydrogen primarily depends on large industrial production that is comparatively expensive and time-consuming. However, renewable resources will be key to hydrogen generation to promote sustainable development. This chapter provides a brief discussion of the possibilities involved in this field by discussing H 2 production via available renewable resources, its economic perspectives, and possible future challenges. This chapter also elaborates on the possibilities involved in this field of CO 2 by further discussing its utilization by reported sources, renewable CO 2 conversion routes, device status and future prospects, and the perspective possibilities of CO 2 at various levels of scientific and industrial startups.
Surface-bound nanomaterials are widely used in clean energy techniques from lithium batteries, solar-driven evaporation in desalination to hydrogen production by photocatalytic electrolysis. Reactive surface nanodroplets may potentially streamline the process of fabrication of a range of surface-bound nanomaterials invoking biphasic reactions at interfaces. In this work, we demonstrate the feasibility of reactive surface nanodroplets for in-situ synthesis and anchoring of nanocaps of metal oxides with tailored porous structures. Spatial arrangement and surface coverage of nanocaps are predetermined during the formation of reactive nanodroplets, while the crystalline structures of metal oxides can be controlled by thermal treatment of organometallic nanodroplets produced from the biphasic reactions. Notably, tuning the ratio of reactive and non-reactive components in surface nanodroplets enables the formation of porous nanocaps that can double photocatalytic efficiency in the degradation of organic contaminants in water, compared to smooth nanocaps. In total, we demonstrate in-situ fabrication of four types of metal oxides in the shape of nanocaps. Our work shows that reactive surface nanodroplets may open a door to a general, fast and tuneable route for preparing surface-bound metal oxides. This fabrication approach may help develop new nanomaterials needed for photocatalytic reactions, wastewater treatment, optical focusing, solar energy conversion and other clean energy techniques.
Chemical composition, morphology and meteorological conditions altogether play a major role to determine the fate of atmospheric particulate matter (PM) deposition and inhalation. Site-wise (#20 sites) and cumulative variations in chemical composition and morphology of PM5 have been studied in Delhi. XRF analysis of PM5 showed major elements like Na, Mg, Al, Si, P, S, Cl, K, Ca, Cr, Fe, Mn, Ni, Cu, Zn, Mo, V, Ag, Co, Pb, Pm, Pd in Delhi’s atmosphere. SEM-EDS analysis of individual particles showed the dominance of both spherical-granular particles and non-spherical- sharp edged, angular and flattened particles rich in elements like C, O, S, N, Al, Si, Cu, Ca, Na, Cl, Fe, Hg, Pb, Mo having potential health effects. Study on meteorological parameters and wind-trajectories shows the effect of both local and regional meteorology in Delhi. #2650 individual particles analyzed for the morphological parameters like AR, CIR, SER and area of individual PM. Cumulative AR:1-1.60 (>70% of particles) is found dominant showing majority of particles are non-spherical whereas dominant cumulative SER (in μm):0-0.50 (>80% of particles) shows that fine fraction is majorly dominated by ultrafine sized particles in Delhi. MPPD Model used to study variations in deposition potential (Regional deposition, Lobar deposition, Mass deposition vs generation number and mass flux) of different PM sizes (PM0.4 , PM1 , PM2.5 and PM5 ) at different AR values (NA, 1 and 1.6). Comparison studies of MPPD Models outputs (up to -56% change in output data) suggested that morphological parameter-AR is an important input parameter of health models to get realistic and unbiased output health data. The study also shows high fraction of coarse particles deposition in the head region affecting upper respiratory tract with their non-spherical shape whereas higher fine particles deposition in TB and pulmonary regions affecting inner parts of lungs.
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