Synthesis of hierarchical wo3 microspheres for photoelectrochemical water splitting application

In this work, hierarchical WO3 microspheres were synthesized using chemical bath deposition. The morphology of the synthesized sample was studied using scanning electron microscopy (SEM). The hierarchical WO3 microspheres formed from spontaneously self-assembled nanosheets have a high specific surface area. Structural characterizations of sample were performed using X-ray diffraction (XRD) and Raman spectroscopy. Analysis of XRD spectra showed that synthesized particles have a monoclinic modification. The optical properties of the sample were studied using UV-Vis diffuse reflectance absorption spectra. The value of the energy gap calculated from the absorption spectra is 2.2 eV, which indicates high light absorption ability. A photocurrent study was done to investigate the photocatalytic activity. The photoelectrode was prepared using hierarchical WO3 microspheres and polymer deposited on fluorine doped tin oxide (FTO) glass via spin coating technique. A remarkable photocurrent density of 18 A/cm2 at 0.5 V was achieved. The elongated structures improved light absorption ability and photocatalytic activity

THREE-DIMENSIONAL FINGERPRINT SPECTROSCOPY STUDY ON THE BIOPOLYMER SYSTEM OF POLYPHENOL OXIDASE BINDING WITH CUMALIC ACID

The protection of Cumalic acid (CA), antioxidant, in the biochemical process in nature has aroused great interest. Polyphenol oxidase (PPO), an enzyme, plays a vital function in aging and browning of plants, such as vegetables, fruits, and mushrooms. The interaction of CA and PPO reveals the important information in metabolism and aging. Thus, the molecular mechanism of CA binding with polyphenol oxidase (PPO) was explored by combining spectroscopic methods with molecular modeling. A three-dimensional fingerprint of the CA-PPO complex was built for the first time to characterize the biopolymer interaction between CA and PPO. Application of the spectroscopic methods indicated that CA effectively quenched the intrinsic fluorescence of PPO. The enthalpy change (ΔH°) and entropy change (ΔS°) suggested that the CA-PPO complex was predominantly stabilized by hydrophobic interactions CA and PPO. Building the λ-UV-F fingerprint of CA-PPO made it possible to demonstrate the three-dimensional interactions between CA and PPO. Subsequently, molecular modeling demonstrated that CA was primarily bound to PPO by hydrophobic interactions and hydrogen bonds located at amino acid residues Ala202, His38, His54, and Ser206. The computational simulations were consistent with the spectral experiments demonstrating confidence in the three-dimensional model determined of the CA-PPO interaction

Chapter 1. Introduction to Green Nanostructured Photocatalysts

Recently, because of major concerns regarding fossil fuels, research in modern societies has focused on the utilization of alternative renewable energy sources in order to meet future energy demands. Solar energy is recognized as the primary source of renewable energy due to its year-round availability and its applications in various fields, such as heating, water splitting, and electricity generation using photocatalysts. The major drawbacks of solar energy conversion systems are their lower conversion efficiency, higher manufacturing and replacement costs, and health and environmental impacts of the materials employed. In order to eliminate such obstacles, many studies have focused on the energy and cost efficiency of solar cells (particularly dye-sensitized solar cells and thin-film solar cells), water-splitting devices, and CO2-capturing systems using various photocatalytic green nanomaterials, such as binary and ternary metal oxides, microorganisms (bacteria, algae, and viruses), and other catalysts and cocatalysts. These materials have been extensively studied because of their many advantages: chemical stability, tunable band gap structures, and abundance on Earth. In this book, we discuss the fundamentals of solar energy conversion, green synthesis approaches using these photocatalysts, the natural photosynthetic system, water splitting, CO2 capture, and organic and inorganic contaminant removal processes using photo-active green nanomaterials, as well as the theory behind these processes and standard measurements for comparisons. We also provide an update of recent developments in the field for the benefit of reader

Introduction to Green Nanostructured Photocatalysts

Recently, because of major concerns regarding fossil fuels, research in modern societies has focused on the utilization of alternative renewable energy sources in order to meet future energy demands. Solar energy is recognized as the primary source of renewable energy due to its year-round availability and its applications in various fields, such as heating, water splitting, and electricity generation using photocatalysts. The major drawbacks of solar energy conversion systems are their lower conversion efficiency, higher manufacturing and replacement costs, and health and environmental impacts of the materials employed. In order to eliminate such obstacles, many studies have focused on the energy and cost efficiency of solar cells (particularly dye-sensitized solar cells and thin-film solar cells), water-splitting devices, and CO2-capturing systems using various photocatalytic green nanomaterials, such as binary and ternary metal oxides, microorganisms (bacteria, algae, and viruses), and other catalysts and cocatalysts. These materials have been extensively studied because of their many advantages: chemical stability, tunable band gap structures, and abundance on Earth. In this book, we discuss the fundamentals of solar energy conversion, green synthesis approaches using these photocatalysts, the natural photosynthetic system, water splitting, CO2 capture, and organic and inorganic contaminant removal processes using photo-active green nanomaterials, as well as the theory behind these processes and standard measurements for comparisons. We also provide an update of recent developments in the field for the benefit of reader

Effects of Electrospinning Parameters on the Morphology of Electrospun Fibers

Hydrophobic electrospun membranes have a lot of applications in different fields. It is very difficult to increase the hydrophobicity of membranes for a specific application. This study investigates the effects of various electrospinning parameters on the morphology and hydrophobicity of polystyrene (PS) electrospun membranes. Polystyrene fibers were used as a reference for the study. Different parameters such as polymer concentrations, diameter of needles, and applied voltage were tested to study the influence on the hydrophobicity of electrospun fibers. Polystyrene fibers were electrospun at different concentrations from 5 to 20 wt.%, needles with a diameter from 0.5 to 3 mm were used, and voltage was applied between 8.06–16.05 kV. The surface morphology of polystyrene fibers and hydrophobicity were studied with a scanning electronic microscope and contact angle measurements. Based on the results of the study, higher polymer concentrations and voltages produce thinner fibers and more hydrophobic membranes. The results of this paper can be applied to the fabrication of different characteristic membranes for specific applications like water conservation, purification, and other fields

Guiding the Nonmagnetic Particles by Magnetic Nanoparticles in a Microfluidic Device Using External Magnetic Fields

A microfluidic device was fabricated via UV lithography technique to separate nonmagnetic fluoresbrite carboxy microspheres (∼4.5 μm) from the ferrofluids made of magnetic nanoparticles (∼10 nm). A mixture of microspheres and ferrofluid was injected to lithographically developed Y shape micro channels, and then by applying the external magnet field, the fluoresbrite carboxy microspheres and ferrofluids were clearly separated into different channels because of the magnetic force acting on those nonmagnetic particles. During the fabrication, a number of different parameters, such as UV exposure times, UV power level and photoresist thickness were tested to optimize for our needs. In addition, in the magnetic field testing, different pumping speeds, and particle concentrations associated with the various distances between the magnet and the microfluidic system were studied for an efficient separation.</jats:p

Thermodynamic Modeling and Process Simulation of Kumkol Crude Oil Refining

The Crude Distillation Unit (CDU) mechanism is commonly regarded as the first stage in petroleum refining. In this study, Aspen Plus® is used to simulate the basic process of a CDU, which consists of an Atmospheric Distillation Column (ATC) and a Vacuum Distillation Column (VC). These columns are fed with two types of crude oil: KUMKOL from Kazakhstan and Soviet Export Blend, in the proportions of 0.75:0.25, 0.50:0.50, and 0.25:0.75, respectively. The goal was to do a parametric analysis and analyze the resultant streams of naphtha, kerosene, Atmospheric Gas Oil (AGO), Light Vacuum Gas Oil (LVGO), and Heavy Vacuum Gas Oil (HVGO). The simulation used the CHAO-SEA thermodynamic model, which included the Chao-Seader correlation, the Scatchard-Hildebrand model, the Redlich-Kwong equation of state, the Lee-Kesler equation of state, and the API gravity technique. Temperature, pressure, mass flow, enthalpy, vapor percentage, and average molecular weights of the streams at various phases within the CDU system were estimated. For both the ATC and VC columns, curves indicating Temperature- Pressure vs the number of stages, as well as ASTM D86 (temperature) versus stream volume % distillation, were developed. The results show that when compared to feed streams containing 0.25 and 0.50 StdVol of Kumkol Kazakhstan Oil, the feed stream with 0.75 StdVol produces more Heavy, Medium, and Light Vacuum Gas Oil (H-VGO, M-VGO, and L-VGO), as well as more Vacuum Gas (VG). These findings indicate that Kumkol Kazakhstan Oil is of high quality and has fewer contaminants, such as sulfur when compared to other accessible mixes throughout the world