321 research outputs found
Synthesis and characterization of silver nanoarticles from extract of Eucalyptus citriodora
The primary motivation for the study to develop simple eco-friendly green synthesis of silver nanoparticles using leaf extract of Eucalyptus citriodora as reducing and capping agent. The green synthesis process was quite fast and silver nanoparticles were formed within 0.5 h. The synthesis of the particles was observed by UV-visible spectroscopy by noting increase in absorbance. Characterization of the particles was carried out by X-ray diffraction, FTIR and electron microscopy. The developed nanoparticles demonstrated that E. citriodora is good source of reducing agents. UV-visible absorption spectra of the reaction medium containing silver nanoparticles showed maximum absorbance at 460 nm. FTIR analysis confirmed reduction of Ag+ to Ag0 atom in silver nanoparticles. The XRD pattern revealed the crystalline structure of silver nanoparticles. The SEM analysis showed the size and shape of the nanoparticles. The method being green, fast, easy and cost effective can be recommended for large scale production of AgNPs for their use in food, medicine and materials
MOF Derived Porous ZnO/C Nanocomposites for Efficient Dye Photodegradation
This is the author accepted manuscript. The final version is available from American Chemical Society via the DOI in this recordHomogeneously dispersed crystalline ZnO nanoparticles embedded in a porous carbon matrix were synthesized via a one-step carbonization of porous metal–organic framework MOF-5 at 800 and 1000 °C in different gas atmospheres. The resulting ZnO/C nanocomposites generally retain cubic particle morphology and high specific surface area of the precursor MOF-5. Various characterization techniques, including XRD, SEM, TEM, elemental mapping, Raman, FTIR, and XPS, confirmed that the carbonization of MOF-5 in water vapor atmosphere produced homogeneously dispersed ZnO nanoparticles confined within the functionalized porous carbon matrix. The rich oxygen-containing hydrophilic functional groups on the surface of the nanocomposite, the defects in the carbon-doped ZnO nanostructure, the crystalline ZnO nanoparticles, and the high textural properties resulted in excellent methylene blue adsorption and photodegradation performance under visible light irradiation. This simple and environmentally friendly approach can be further employed to harvest a variety of new homogeneously dispersed functional metal oxide/carbon composites for various environment and energy related applications.Engineering and Physical Sciences Research Council (EPSRC)Deutsche Forschungsgemeinschaft (German Research Council
Porous ZnO/Carbon nanocomposites derived from metal organic frameworks for highly efficient photocatalytic applications - A correlational study
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record Porous ZnO/C nanocomposites derived from 3 different Zinc based metal-organic frameworks (MOFs) including MOF-5, MOF-74 and ZIF-8, were prepared at high temperature under water-steam atmosphere and their performances in photocatalytic H 2 evolution reaction (HER) and photodegradation of organic dye pollutants were evaluated. The formation mechanism from MOF precursors, the structural properties, morphologies, compositions and textural properties of the derived ZnO/C composites were fully investigated based on different characterization techniques and the correlation between the precursors and the derived composites was discussed. It is evident that MOF precursors determine the crystalline structures, doping profiles, thermal stabilities and metal oxide-carbon weight percentage ratios of the resulting composites. The correlation between MOFs and their derived nanocomposites indicates that different parameters play unalike roles in photocatalytic performances. The desired properties can be tuned by selecting appropriate MOF precursors. MOF-5 derived porous ZnO/C nanocomposite not only exhibits the highest photocatalytic dye degradation activity under visible light among these MOFs, but also outperforms those derived from MOF-74 and ZIF-8 up to 9 and 4 times in photocatalytic HER respectively. This study offers simple and environmentally friendly approaches to further develop new homogeneously dispersed functional metal oxide/carbon composites for various energy and environment-related applications.Engineering and Physical Sciences Research Council (EPSRC)European Commissio
Bimetallic Fe-Mo sulfide/carbon nanocomposites derived from phosphomolybdic acid encapsulated in MOF for efficient hydrogen generation
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordTo tackle the energy crisis and achieve a more sustainable development, hydrogen as a clean
and renewable energy resource has attracted great interest. Searching for cheap but efficient
catalysts for hydrogen production from water splitting is urgently needed. In this report,
bimetallic Fe-Mo sulfide/carbon nanocomposites that derived from a polyoxometalate
phosphomolybdic acid encapsulated in metal organic framework MIL-100 (PMA@MIL-100)
have been generated and their applications in electrocatalytic hydrogen generation were
explored. The PMA@MIL-100 precursor is formed via a simple one-pot hydrothermal
synthesis method and the bimetallic Fe-Mo sulfide/carbon nanocomposites were obtained by
chemical vapour sulfurization of PMA@MIL-100 at high temperatures. The nanocomposite
samples were fully characterized by a series of techniques including XRD, FT-IR, TGA, N2
gas sorption, SEM, TEM, XPS, and were further investigated as electrocatalysts for hydrogen
production from water splitting. The hydrogen production activity of the best performed
bimetallic Fe-Mo sulfide/carbon nanocomposite exhibits an overpotential of -0.321 V at 10
mA cm-2
and a Tafel slope of 62 mV dec-1 with a 53% reduction in overpotential compared to
Mo-free counterpart composite. This dramatic improvement in catalytic performance of the FeMo sulfide/carbon composite is attributed to the homogeneous distribution of the nanosized
iron sulfide, MoS2 particles and the formation Fe-Mo-S phases in the S-doped porous carbon
matrix. This work has demonstrated a potential approach to fabricate complex heterogeneous
catalytic materials for different applications.Engineering and Physical Sciences Research Council (EPSRC)Leverhulme TrustEuropean Unio
Recent Advances in Metal–Organic Frameworks Derived Nanocomposites for Photocatalytic Applications in Energy and Environment
This is the final version. Available from Wiley via the DOI in this record. Solar energy is a key sustainable energy resource, and materials with optimal properties are essential for efficient solar energy-driven applications in photocatalysis. Metal–organic frameworks (MOFs) are excellent platforms to generate different nanocomposites comprising metals, oxides, chalcogenides, phosphides, or carbides embedded in porous carbon matrix. These MOF derived nanocomposites offer symbiosis of properties like high crystallinities, inherited morphologies, controllable dimensions, and tunable textural properties. Particularly, adjustable energy band positions achieved by in situ tailored self/external doping and controllable surface functionalities make these nanocomposites promising photocatalysts. Despite some progress in this field, fundamental questions remain to be addressed to further understand the relationship between the structures, properties, and photocatalytic performance of nanocomposites. In this review, different synthesis approaches including self-template and external-template methods to produce MOF derived nanocomposites with various dimensions (0D, 1D, 2D, or 3D), morphologies, chemical compositions, energy bandgaps, and surface functionalities are comprehensively summarized and analyzed. The state-of-the-art progress in the applications of MOF derived nanocomposites in photocatalytic water splitting for H2 generation, photodegradation of organic pollutants, and photocatalytic CO2 reduction are systemically reviewed. The relationships between the nanocomposite properties and their photocatalytic performance are highlighted, and the perspectives of MOF derived nanocomposites for photocatalytic applications are also discussed.Leverhulme TrustEngineering and Physical Sciences Research Council (EPSRC
Recommended from our members
MERLIN - A meV resolution beamline at the ALS
An ultra-high resolution beamline is being constructed at the Advanced Light Source (ALS) for the study of low energy excitations in strongly correlated systems with the use of high-resolution inelastic scattering and angle-resolved photoemission. This new beamline, given the acronym Merlin (for meV resolution line), will cover the energy range 10-150 eV. The monochromator has fixed entrance and exit slits and a plane mirror that can illuminate a spherical grating at the required angle of incidence (as in the SX-700 mechanism). The monochromator can be operated in two different modes. In the highest resolution mode, the energy scanning requires translating the monochromator chamber (total travel 1.1 m) as well as rotating the grating and the plane mirror in front of the grating. The resolution in this mode is practically determined by the slits width. In the second mode, the scanning requires rotating the grating and the plane mirror. This mode can be used to scan a few eV without a significant resolution loss. The source for the beamline is a 1.9 m long, 90 mm period quasi periodic EPU. The expected flux at the sample is higher than 10 photons/s at a resolving power of 5 × 10 in the energy range 16-130 eV. A second set of gratings can be used to obtain higher flux at the expense of resolution. © 2007 American Institute of Physics. 11
Comparative Biochemical Evaluation of Schizothorax niger and Cyprinus carpio from River Jhelum of Kashmir Valley
ABSTRACT The present study was conducted to evaluate the comparative biochemical profile of Schizothorax niger (endemic fish) and Cyprinus carpio (exotic fish) from the River Jhelum seasonally for a period of two years. .98 mg/dl). In both the fish hosts the higher biochemical values were recorded in the summer season and the lower values in the winter season during the study period. The seasonal differences in the biochemical parameters of the fish can be attributed to the water pollution of River Jhelum by various contaminants including metals and the comparative higher values in Schizothorax niger can be speculated to be due to the higher sensitivity of the host. From the present study it may be inferred that the change in biochemical parameters of the native fish would be one of the reasons for its decline from fresh water resources of the Kashmir Valley
Recommended from our members
A Comparative Study of Single and Multi-Stage Forecasting Algorithms for the Prediction of Electricity Consumption Using a UK-National Health Service (NHS) Hospital Dataset
Data Availability Statement: Restrictions apply to the availability of the electricity consumption data. The data belong to Medway NHS Foundation Trust but were collected using systems provided by EnergyLogix. Data, however, can be made available with the approval of the corresponding author (A.T.), Medway NHS Foundation Trust, and EnergyLogix. As for the weather data, they were obtained from [24].Copyright © 2023 by the authors. Accurately looking into the future was a significantly major challenge prior to the era of big data, but with rapid advancements in the Internet of Things (IoT), Artificial Intelligence (AI), and the data availability around us, this has become relatively easier. Nevertheless, in order to ensure high-accuracy forecasting, it is crucial to consider suitable algorithms and the impact of the extracted features. This paper presents a framework to evaluate a total of nine forecasting algorithms categorised into single and multistage models, constructed from the Prophet, Support Vector Regression (SVR), Long Short-Term Memory (LSTM), and the Least Absolute Shrinkage and Selection Operator (LASSO) approaches, applied to an electricity demand dataset from an NHS hospital. The aim is to see such techniques widely used in accurately predicting energy consumption, limiting the negative impacts of future waste on energy, and making a contribution towards the 2050 net zero carbon target. The proposed method accounts for patterns in demand and temperature to accurately forecast consumption. The Coefficient of Determination (R2), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE) were used to evaluate the algorithms’ performance. The results show the superiority of the Long Short-Term Memory (LSTM) model and the multistage Facebook Prophet model, with R2 values of 87.20% and 68.06%, respectively.Engineering and Physical Sciences Research Council (EPSRC) grants, EP/T517896/1
An in situ investigation of the thermal decomposition of metal-organic framework NH2-MIL-125 (Ti)
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordTitanium based metal-organic frameworks (MOFs) are interesting self-sacrificial precursors to derive semiconducting porous nanocomposites for highly efficient heterogeneous catalysis. However, there is a lack of systematic and in-depth mechanistic understanding of the pyrolytic conversion of MOF precursors into the desired functional composite materials. In this work, TGA-MS and in situ STEM/EDX combined with other characterization techniques were employed to investigate the evolution of the structural, physicochemical, textural and morphological properties of NH2-MIL-125(Ti) pyrolysis at different temperatures in an inert gaseous atmosphere. In situ thermal analysis of NH2-MIL-125(Ti) reveals the presence of 3 rather defined stages of thermal transformation in the following order: phase-pure, highly porous and crystalline MOF → intermediate amorphous phase without accessible porosity → recrystallized porous phase. The three stages occur from room temperature till 300 °C, between 350 and 550 °C and above ∼550 °C respectively. It is found that the framework of NH2-MIL-125(Ti) starts to collapse around 350 °C, accompanied with the cleavage of coordination and covalent bonds between organic linkers [O2C–C6H3(NH2)–CO2]6 and the Ti oxo-cluster Ti8O8(OH)4. The organic linker continues fragmentation at 450 °C causing the shrinkage of particle sizes. The dominant pore size of 0.7 nm for NH2-MIL-125(Ti) gradually expands to 1.4 nm at 800 °C along with the formation of mesopores. The derived disc-like particles exhibit an approximately 35% volume shrinkage compared to the pristine MOF precursor. Highly crystalline N and/or C self-doped TiO2 nanoparticles are homogeneously distributed in the porous carbon matrix. The original 3D tetragonal disc-like morphology of the NH2-MIL-125(Ti) remains preserved in derived N and/or C doped TiO2/C composites. This study will provide an in-depth understanding of the thermal conversion behavior of MOFs to rationally select and design the derived composites for the relevant applications.Engineering and Physical Sciences Research Council (EPSRC)Deutsche Forschungsgemeinschaf
- …