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Transition metal oxides were fabricated by a facile solvothermal route. The hierarchical NiCo2O4 electrocatalyst exhibited enhanced water oxidation performance due to the unique teddy bear sunflower-like morphology.

The design of efficient and low-cost catalysts for water oxidation with superior electrochemical performance is of great importance. Herein, we report on the fine-tuning of water oxidation performance using solvothermal fabricated hierarchical nanostructured Co3O4 catalysts obtained from three different cobalt precursors. The prepared hierarchical Co3O4 nanostructured catalysts were intensively analyzed for their textural properties and surface chemistry, such as shape, size, phase and surface area. The water oxidation performance of all three catalysts through the oxygen evolution reaction (OER) has been investigated. In alkaline 1 M KOH aqueous solution, the ultrathin hierarchical Co3O4–S nanosheet array catalyst exhibits significantly higher activity during water oxidation, with a low overpotential of 330 mV vs. RHE at a benchmarking current density of 10 mA cm−2 for OER in comparison with Co3O4–Ac and Co3O4–N, which outperforms a commercial RuO2 electrocatalyst, and it remains stable for many hours. Benefiting from its unique ultrathin architecture, hierarchical and nanostructured Co3O4–S is endowed with a large number of active sites and a rapid charge transfer process, resulting in better water oxidation performance.

Highly efficient, low-cost electrocatalysts having superior activity and stability are crucial for practical electrochemical water splitting, which involves hydrogen and oxygen evolution reactions (HER and OER). The sustainable production of hydrogen fuel from electrochemical water splitting requires the development of a highly efficient and stable electrocatalyst with low overpotential that drives electrochemical redox reactions. Electrochemical water splitting using highly active nickel-iron layered double hydroxide (NiFe LDH) catalyst having a very high turnover frequency and mass activity is considered as a potential contender in the area of electrocatalysis owing to the practical challenges including high efficiency and long durability at low overpotential, which shows great potential in future hydrogen economy. This review includes certain recommendations on enhancing the electrocatalytic performance of NiFe LDH-based electrocatalyst, particularly through morphology engineering, construction of hierarchical/core–shell nanostructures, and doping of heteroatoms through combined experimental assessment and theoretical investigations, which in turn improve the electrocatalytic performance. Finally, emphasis is made on the bifunctional activity of the NiFe LDH catalyst for overall water splitting. At the end, the conclusions and future outlook for the design of the NiFe LDH catalyst towards scale-up for their use as electrolyzer at the industrial level are also discussed.

Amongst various futuristic renewable energy sources, hydrogen fuel is deemed to be clean and sustainable. Electrochemical water splitting (EWS) is an advanced technology to produce pure hydrogen in a cost-efficient manner. The electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are the vital steps of EWS and have been at the forefront of research over the past decades. The low-cost nanostructured metal phosphide (MP)-based electrocatalysts exhibit unconventional physicochemical properties and offer very high turnover frequency (TOF), low over potential, high mass activity with improved efficiency, and long-term stability. Therefore, they are deemed to be potential electrocatalysts to meet practical challenges for supporting the future hydrogen economy. This review discusses the recent research progress in nanostructured MP-based catalysts with an emphasis given on in-depth understanding of catalytic activity and innovative synthetic strategies for MP-based catalysts through combined experimental (in situ/operando techniques) and theoretical investigations. Finally, the challenges, critical issues, and future outlook in the field of MP-based catalysts for water electrolysis are addressed.

The monomer dispersed liquid crystal is relatively new class of functional materials which has a numerous role in the modern technology. This research work reports the effect of two different concentrations of monomer 2-Ethyl Hexyl Acrylate with on liquid crystals of cholesteryl nonanoate. This monomer is selected due to its low volatile nature and reactivity of double bonds. The thermal behaviour of samples under investigations was studied by differential scanning calorimetry (DSC). The liquid crystal shows a good miscibility with both concentrations of monomer which were confirmed by Fourier transform infrared (FTIR) spectroscopy. The proposed research investigation reveals new phase transitions along with the known phase transitions for this composite system. It was also observed that in the nematic order, the molecules tend to align perpendicular to the surface. This opens a new possibility of this material to be used for variety of new applications like photo-cured network and photopolymer etc.

The Himalayan region is facing frequent cloud bursts and flood events during the summer monsoon season. The Kedarnath flooding of 2013 was one of the most devastating recent events, which claimed thousands of human lives, heavy infrastructure, and economic losses. Previous research reported that the combination of fast-moving monsoon, pre-existing westerlies, and orographic uplifting were the major reasons for the observed cloud burst over Kedarnath. Our study illustrates the vertical distribution of aerosols during this event and its possible role using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) simulations. Model performance evaluation shows that simulations can capture the spatial and temporal patterns of observed precipitation during this event. Model simulation at 25 km and 4 km horizontal grid resolution, without any changes in physical parameterization, shows a very minimal difference in precipitation. Simulation at convection-permitting scale shows detailed information related to parcel motion compared to coarser resolution. This indicates that the parameterization at different resolutions needs to be further examined for a better outcome. The modeled result shows changes of up to 20–50% in the rainfall over the area near Kedarnath due to the presence of aerosols. Simulation at both resolutions shows the significant vertical transport of natural (increases by 50%+) and anthropogenic aerosols (increases by 200%+) during the convective event, which leads to significant changes in cloud properties, rain concentration, and ice concentration in the presence of these aerosols. Simulations can detect changes in important instability indices such as convective available potential energy (CAPE), convective inhibition energy (CIN), vorticity, etc., near Kedarnath due to aerosol–radiation feedback.

Oxygen evolution reaction (OER) in water splitting is one of the most critical and more demanding half-reactions in electrochemical devices; therefore, the design of highly efficient and nonprecious metal-based electrocatalysts is required. Herein, we presented the fast microwave synthesis of the solid nanorods of Co(OH)2 and their conversion into interconnected porous nanorods of Co3O4 by high-temperature calcination for exposing active sites, which offered a high surface area; this resulted in faster exchange of intermediates and more efficient electron transfer for enhanced OER activities in alkaline solutions. The as-synthesized solid Co(OH)2 and calcined porous Co3O4 nanorod catalysts were characterized by scanning and transmission electron microscopies (SEM and TEM), powder X-ray diffraction (PXRD), and X-ray photoelectron spectroscopy (XPS); finally, the OER performance was investigated for water oxidation. FE-SEM and HR-TEM images revealed the formation of solid nanorods of as-synthesized Co(OH)2, which were broken and converted into porous interconnected nanorods after calcination at a high temperature. In 0.1 M KOH aqueous electrolyte, solid Co(OH)2 @ 120 °C nanorods did not have favorable OER activity, while the Co3O4 @ 600 °C electrocatalyst exhibited a low onset potential (1.55 V vs. RHE) and Tafel slope (49 mV dec−1), maintaining robust stability for more than 18 h with negligible fading. This is mainly because the interconnected porous nanorod Co3O4 @ 600 °C catalyst possessed rich active boundary sites and short paths for charge/mass transport (higher reactivity of active sites) than Co3O4 @ 400 °C and Co(OH)2 @ 120 °C. Such high catalytic activity was attributed to the sufficient exposure of the accessible active sites of porous Co3O4 electrocatalysts.

Ferroelectric nano-materials are very sensitive to several external stimuli and have attracted great deal of attention due to their property of improving various properties such as photoluminescence, higher polarization, fast response time, low operating voltage and improved conductivity. For enhancing the physical properties, a proper selection of nano-materials for liquid crystals depends upon various factors such as size, shape, preparation methods, surfactant concentration and amount of doping materials. In the present study an attempt is made to study electrical and acoustical properties of cholesteric liquid crystal after dispersing ferroelectric nano-powder of Barium Titanate (BaTiO3). In addition with this particle size and surface area of pure and nono-particle dispersed liquid crystal were also measured. Our investigation shows increase in Rao’s constant or molar sound velocity, which indicates increase in molecular density indicating a close packing of the material. The measurement of dielectric relaxation at different frequencies gives information about the dynamics of polar groups and molecular motion.

Seasonal open biomass burning contributes to significant carbonaceous aerosol loading over South Asia. This study analyzes long-term trends in emissions in two hot spot regions, Myanmar and Punjab, based on data from the Global Fire Emissions Database (GFED4s) and Fire INventory (FINN) from the National Center for Atmospheric Research (NCAR). Our analysis reveals that emissions during active fire seasons increase by approximately 83–106% and 2338–3054% for Punjab and Myanmar, respectively, compared to the estimates of anthropogenic emissions obtained with FINN. We also examine the impact of carbonaceous aerosol from open biomass burning on regional weather by using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to conduct a year-long simulation of the post-monsoon and pre-monsoon periods when active fires were reported. The results indicate that the carbonaceous aerosol is vertically lofted by as much as 3–5 km into the atmosphere and, rising as high as the 850 hPa level from the surface, disperses horizontally throughout South Asia. Our calculations on the radiative forcing suggest that changes of up to –6.14 W m–2 and –0.50 W m–2, and –42.76 W m–2 and –1.91 W m–2 occur at the surface and at the top of the atmosphere over Punjab and Myanmar, respectively. We also find that carbonaceous aerosol (black carbon + organic carbon), similar to black carbon (BC), reduces the surface temperature, despite the scattering effects of organic carbon (OC). Overall, open biomass burning causes the surface temperature to decrease by 2 K, the relative humidity to increase by 8% and the planetary boundary layer height to change by as much as 600 m. Changes in the precipitation patterns and volume due to the carbonaceous aerosol from open biomass burning, however, are negligible when considering only the direct radiative feedback.

In current report, the investigation of synthesis of silica aerogel composite by reinforcing metal oxide particle nickel nitrate hexahydrate [Ni (NO3)2.6H2O)] as a filler into SiO2 matrix. In silica matrix with the help of tetraethoxysilane (TEOS),ethanol and oxalic acid catalyst ,using sol-gel technique followed by high temperature(N2 gas) solvent extraction with supercritical drying technique. The obtained aerogel doped with nickel nitrate display a well developed porous structure, excellent physical properties with less volume shrinkage, extremely high specific surface area (794.3 m²/g), average pore size of 240 nm. The aerogel composite possessed a BET specific surface area even after calcinations of 500oC for 4 hours by maintaining the pore shrinkage with the supporting skeletons nickel nitrate contents. The cross-linked aerogel composite, structural and physical properties were investigated by XRD (X-ray diffraction), field emission scanning electron microscopy (FE-SEM), Fourier- transform infrared-spectroscopy (FT-IR) and Brunauer, Emmett and Teller (BET) and BJH nitrogen gas adsorption-desorption.

Polymer is substance which consists of large number of molecules and plays a very important in our everyday life. In the present study the effect of different concentration of polymer Poly Methyl Methacrylate on the optical and thermal properties of nematic liquid crystal were investigated. The polymer was dispersed in the liquid crystal by polymerization induced phase separation method. The physical properties were investigated using differential scanning calorimetry and polarized optical microscopy. We found various textures according to the molecular order and orientation of the liquid crystal and polymer in constrained regions separated by phase boundaries. These composite materials can be used to enhance contrast ratio with more stability for display application and smart window.

Liquid Crystals (LCs) have attracted significant attraction from scientific community due to their several applications. However, pure liquid crystals have main problem of slow response to various ...

In this paper we investigate the possibility of formation of Anatase TiO2 and nitrogen doped TiO2thin films prepared by varying cathodic arc evaporation parameters such as ratio of Ar, O2 and N2 gas flow, bias voltage and cathode current. Nanostructured titanium dioxide (TiO2) and nitrogen doped titanium dioxide (N-TiO2) thin films were deposited on soda lime silicate glass samples using Cathodic Arc Physical Vapor Deposition (CA-PVD). X-ray diffraction (XRD), UV-Vis spectrophotometer and scanning electron microscope (SEM) technologies were used to characterize the film. The photocatalytic activities of the samples were tested on the degradation of methylene blue (MB) dye. Crystalline size and phases of the thin films were calculated by using XRD. Morphology and elemental analysis of the thin films were carried by SEM-EDAX. Here, we intensely say that as deposited thin films gives better degradation efficiency without any additional process.

The photocatalytic performance of gC3N4 is majorly restricted by insufficient collection of photogenerated charges on the surface during reaction due to highly dense stacking of lamellar structures with lateral size ranging in microns. This deficiency can be overcome by forming thin nanoflakes by systematically breaking the weak bonds that hold the gC3N4 framework without destroying the basic heptazine unit. With this aim, herein, a combination of three different strategies was implemented to design and develop, Ag-loaded and P-doped gC3N4 nanoflakes (Ag3-P1-NF-gC3N4). Using a systematic synthesis method, bulk gC3N4 was first converted into thin nanosheets, followed by fragmentation into nanoflakes, with a planar size up to 100 nm. P doping to replace the corner C atoms in the gC3N4 matrix (forming P N bonds) and intercalation of plasmonic Ag nanoparticles within the interlayers also assists in the bifurcation of the stacked layers and formation of nanoflake morphology. These strategies result in a significant increase in BET surface area to ∼196 m2/g from 12 m2/g of bulk gC3N4. Improved inter-planar and intra-planar charge mobility was recorded as a result of the reduced sizes. Doping with P also causes higher absorption of the visible spectrum in gC3N4 while the formation of heterojunction with Ag nanoparticles induces efficient separation of photo-generated charges. All these promoting photo-physical properties lead to an outstanding photocatalytic activity towards degradation of aqueous pollutants with reaction rates ∼20 times higher than bulk gC3N4. Complete mineralization of the pollutant and formation of non-toxic byproducts was also confirmed with suitable chromatography techniques.

In the present study, the optical, thermal, and mechanical properties of liquid crystal elastomers (LCEs) were investigated using various techniques. The presence of functional groups in LCE was studied using Fourier transform infrared spectroscopy. The phase transition temperatures were confirmed via polarizing optical microscopy and Fabry–Perot scattering studies. The differential thermal analysis was used for investigating the thermal behavior. A dynamic mechanical analysis was used to study the mechanical properties of LCE. The significant mechanical changes with a considerable reversible effect were observed for this soft material. The changes in the mechanical shape with the temperature are attributed to the change in the phase of the LCE material.

Gold nanoparticles (Au NPs) of different sizes were supported on fibrous silica nanospheres (KCC-1) by various methods. The size and the location of the Au NPs on the support were found to depend on the preparation method. The KCC-1-supported Au NPs were thoroughly characterized by using HR-TEM, XRD, X-ray photoelectron spectroscopy, UV, and Brunauer–Emmett–Teller surface area measurements and were applied in catalysis for the oxidation of CO. The catalytic performance is discussed in relation to the morphological properties of KCC-1.

This study uses Weather Research and Forecasting model, coupled with Chemistry (WRF-Chem), to understand black carbon (BC) vertical transport over South Asia during the active convection period. We analyze the climatology (1995–2014) of convective weather using TRMM lightning data. The results show both temporal and spatial variability within South Asia. The WRF-Chem model simulation for BC transport was conducted for an ENSO (El-Nino Southern Oscillation) moderate year - 2013. The model simulates the observed concentrations trend for most of the region except the central Himalayan cities. Our analysis indicates the dominant role of synoptic atmospheric dynamics and upper boundary conditions for the inverted seasonal trend of BC during the pre-monsoon season over these cities. The study presents time series and seasonal scale analysis of BC concentration over South Asia at various altitude levels. Our model simulations suggest that free troposphere (FT) BC concentration is higher in the monsoon season compared to the winter season at the same elevation. In addition, our results show the presence of a persistent BC plume from 500 hPa and above over central India with implications for the summer monsoon. The presence of an anti-cyclonic region during the monsoon season at the higher troposphere (500–300 hPa) contributes to this stable BC layer. Although individual high convection days (high helicity/CAPE) can easily transport a significant amount of BC from the surface to the FT, simulations do not show significant BC transported to the upper troposphere-lower stratosphere during these days. While satellite derived products provide some insights into model predictions, there is a need for in-situ measurements of BC concentration aloft over South Asia to further constrain model performance and improve understanding of BC transport to FT.

We report a method to synthesize low-density transparent mesoporous silica aerogel beads by ambient pressure drying (APD). The beads were prepared by acid–base sol–gel polymerization of sodium silicate in via the ball dropping method (BDM). To minimize shrinkage during drying, wet silica beads were initially prepared; their surfaces were then modified using trimethylchlorosilane (TMCS) via simultaneous solvent exchange and surface modification. The specific surface area and cumulative pore volume of the silica aerogel beads increased with an increase in the %V of TMCS. Silica aerogel beads with low packing bed density, high surface area, and large cumulative pore volume was obtained when TMCS was used. Properties of the final product were examined by BET, and TG–DT analyses. The hydrophobic silica aerogel beads were thermally stable up to 350°C. We discuss our results and compare our findings for modified versus unmodified silica beads.

An efficient palladium catalyst supported on fibrous silica nanospheres (KCC-1) has been developed for the hydrogenation of alkenes and α,β-unsaturated carbonyl compounds, providing excellent yields of the corresponding products with remarkable chemoselectivity. Comparison (high-resolution TEM, chemisorption) with analogous mesoporous (MCM-41, SBA-15) silica-supported Pd nanocatalysts prepared under identical conditions, demonstrates the advantage of employing the fibrous KCC-1 morphology versus traditional supports because it ensures superior accessibility of the catalytically active cores along with excellent Pd dispersion at high metal loading. This morphology ultimately leads to higher catalytic activity for the KCC-1-supported nanoparticles. The protocol developed for hydrogenation is advantageous and environmentally benign owing to the use of HCOOH as a source of hydrogen, water as a solvent, and because of efficient catalyst recyclability and durability. The recycled catalyst has been analyzed by XPS spectroscopy and TEM showing only minor changes in the oxidation state of Pd and in the morphology after the reaction, thus confirming the robustness of the catalyst.

Liquid crystal composite materials with tunable physical properties are of great scientific interest because of optoelectronic and biomedical applications. We report our study of modified optical properties of 5CB Nematic Liquid Crystal (NLC) by doping with ferrofluid at low concentrations of 0.1% by the investigation of thermo optic behaviour. The observed sensitivity of optical response in ferrofluid doped NLC is expected to pave way for several thermo-optic applications.

Developing stable, ubiquitous, and efficient water-splitting photocatalyst material that has extensive absorption in the visible-light range is desired for a sustainable solar energy-conversion device. We herein report a triazine-based carbon nitride (CN) material with different C/N ratios achieved by varying the monomer composition ratio between melamine (Mel) and 2,4,6-triaminopyrimidine (TAP). The CN material with a different C/N ratio was obtained through a two-step synthesis protocol: starting with the solution state dispersion of the monomers via hydrogen-bonding supramolecular aggregate, followed by a salt-melt high temperature polycondensation. This protocol ensures the production of a highly crystalline polytriazine imide (PTI) structure consisting of a copolymerized Mel-TAP network. The observed bandgap narrowing with an increasing TAP/Mel ratio is well simulated by density functional theory (DFT) calculations, revealing a negative shift in the valence band upon substitution of N with CH in the ...

Dispersion of Carbon Nanotube (CNT) into Liquid Crystal Elastomers (LCE) provides simple and effective means of controlling physical properties at macroscopic scale. In this paper, we doped LCE with small amount of carbon nanotube and characterizations were performed by various techniques like Polarizing Microscopy Study (PMS), Fabry Perot Scattering Studies (FPSS), Fourier Transform Infrared (FTIR) Spectroscopy, Data Thermal Analysis (DTA) and Mechanical Study. The experimental results reveal that optical, thermal and mechanical properties are function of doped CNT material, which reflected strong agglomeration and rearrangement of nanotubes in LCE. Therefore, a small amount of CNT enhances existing properties which can be optimized for various applications.