2021

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A simulation study of dose deposition in a Fano Cavity using MonteCarlo code
(UMT, Lahore, 2021) MARIA FAROOQ
In this work, the electron transport algorithm is examine using Monte Carlo GEANT4 code. To perform simulation of an ionization chamber composed for water for 1.25MeV incidentphoton beam using FanoCavity and evaluate the consistency of the cavity response for variouscombinations of electron transport parameters. Due to this, electron reach geometric boundaries in large steps, and lateral displacement near interfaces is estimated by GEANT4. A number of histograms simulation results are plotted in Root to demonstrate the behavior of electrons in Fano Cavity response. As part of the FanoCavity setup, several improvements have been madeto electron transport algorithms. The number of events increases as well as the number ofelectrons inside the cavity and the highest energy peak is obtained. It is observed that theFanoCavity accuracy was greatly affected by the electron step size in the GEANT4 MC code.
A simulation study of dose deposition in a fano cavity using montecarlo code
(UMT, Lahore, 2021) MARIA FAROOQ
In this work, the electron transport algorithm is examine using Monte Carlo GEANT4 code. To perform simulation of an ionization chamber composed for water for 1.25MeV incident photon beam using FanoCavity and evaluate the consistency of the cavity response for various combinations of electron transport parameters. Due to this, electron reach geometric boundaries in large steps, and lateral displacement near interfaces is estimated by GEANT4. A number of histograms simulation results are plotted in Root to demonstrate the behavior of electrons in Fano Cavity response. As part of the FanoCavity setup, several improvements have been made to electron transport algorithms. The number of events increases as well as the number of electrons inside the cavity and the highest energy peak is obtained. It is observed that the FanoCavity accuracy was greatly affected by the electron step size in the GEANT4 MC code.
A study of copper nano-particles by laser ablation method in air and liquid
(UMT, Lahore, 2021) Syed Danial Naseer
The use of copper nanoparticles which acts as anti-biotic, antimicrobial, and anti-fungal agent in materials such as plastics, coatings, and textiles has been studied. Cu nanoparticles have extraordinary properties in the ultraviolet and visible spectrums, as well as in electrical, catalytic, thermal, and antibacterial applications. This is due to quantum effects and a high surface-to volume ratio. It is now being investigated how copper nanoparticles can be used in applications to uncover their potential dielectric and magnetic characteristics as well as their opto-electrical, imaging, catalytic and biological and bioscience capabilities. Creating copper nanoparticles is possible through a variety of processes, including chemical, physical, and biological approaches. Every approach has its own set of disadvantages and limits, and the most widely used technique is no exception. For the purpose of avoiding contamination and impurity contamination in the synthesized products, the researchers employed various types of laser assisted technologies, such as laser ablation of solids in the liquid phase (LASL) and laser ablation of the solids in open air (LASOA), in this work. These technologies are viable alternatives to chemical reduction methods, particularly when considering their potential applications in biological systems. The Nd:YAG laser used in this work is a pulsed Q-switched Nd:YAG laser. An investigation has been conducted on the impact of various processing parameters on Np's form, size, and crystalline phase. There were only pure Cu nanoparticles recovered, and they were all of the same spherical form and homogeneous size distribution. It is necessary to study the morphology, size, along with the optical features of the colloidal solution nanoparticles created using a Transmission Electron Microscopy (TEM).
Capacitive and resistive type bi-modal relative humidity sensor based on 5,10,15,20-tetraphenylporphyrinatonickel (II) (TPPNi) zinc oxide (ZnO) nanocomposite
(UMT, Lahore, 2021) Muhammad Saleem
The selection of the appropriate sensing material and efficient manufacturing methodology is needed to develop an acceptable approach for the production of thin film-based moisture sensors with better electronic sensitivities. Organic semiconductors and their nano-composite have the potential for relative humidity sensing applications since they have a controllable pore size, a broad variety of manufacturing methods, ease of fabrication, and low cost The use of organic semiconductor 5,10,15,20-tetraphenylporphyrinatonickel (II) (TPPNi) – Zinc Oxide (ZnO) nanocomposite (TPPNi-ZnO) to build ultra-sensitive humidity sensors has been studied in this work utilizing a unique eco-friendly microwave-assisted synthesis method. The organic semiconductor (5,10,15,20-tetraphenylporphyrinatonickel (II) (TPPNi)) and metal oxide (Zinc Oxide (ZnO)) has been synthesized separately and deposited through facile drop-casting technique on the separation (40 μm) between the pair of aluminum (Al) electrodes. The metallic electrode thus formed a surface type resistive and capacitive type humidity sensor (Al/TPPNi-ZnO/Al). The photophysical properties of humidity sensing active layer (TPPNi - ZnO) has been studied by using UV–vis absorption spectroscopy and the structural and morphological has been examined by XRD and FESEM, which shows amorphous structure and rough globular surface morphology of the active surface thin film. The relative humidity sensing capacitive and resistive characteristics of the humidity sensor have been explored by exposing it to various wide range relative humidity (%RH) levels (40 - 85 %RH). The fabricated sensor under biasing condition of 1V of applied bias (Vrms) and 500 Hz AC test frequency, exhibits significantly higher sensitivity of ~ 387.03 pF/%RH and 95.79 kΩ/%RH in capacitive and resistive mode of operation. The average response time and recovery time of this resistive sensor have evaluated to be ~ 30 s, each. The reasons of this achieved sensitivity and response level has also been discussed.
Development of highly sensitive relative humidity sensor based on nanoporous PCPDTBT thin film
(UMT, Lahore, 2021) FOQIA SHAFIQ
The pursuit of an appropriate method to fabricate thin-film-based humidity sensors with superior sensitivity in their electrical response calls for the selection of (a) appropriate materials and (b) effective fabrication techniques. Organic porous polymer semiconductors have particularly significant potential for relative humidity sensing applications as they offer controlled pore size, low cost and a vast variety of fabrication procedures along with an inherent advantage of mechanical flexibility. In the present work, we have investigated the utilization of porous organic semiconductor material (PCPDTBT) to fabricate a highly sensitive humidity sensor. Low bandgap copolymer PCPDTBT has been commercially procured and deposited through the facile drop-casting technique on the gap (40 μm) between a set of planar aluminum (Al) electrodes to fabricate a planar resistive and capacitive type humidity sensor (Al/PCPDTBT/Al). The structural and morphological characterizations of relative humidity sensing active layer have been performed by XRD and FESEM which indicate the amorphous structure and porous surface morphology of the active surface thin film. The relative humidity sensing capacitive and resistive characteristics of the humidity sensor have been explored by exposing it to various wide range relative humidity (%RH) levels (40 - 85 %RH). The fabricated sensor under the biasing condition of 1V of applied bias Vrms and 1kHz AC test frequency, exhibits significantly higher sensitivity of ~ 415.07 pF/%RH and -3624.88 kΩ/%RH in the capacitive and resistive mode of operation. The average response time and recovery time of this capacitive and resistive sensor have been evaluated to be ~ 4 min 17s and ~8 min 43s, respectively. The reasons for this achieved sensitivity and response level have been discussed.
Effect of different liquid enivronment on the quality of copper nano particles by laser ablation method
(UMT, Lahore, 2021) Shah Nawaz
The synthesis and application of metal and ceramic nanoparticle are significant subject in science and engineering. The Copper nanoparticles has more application in material science, Nano medicine and electronic. One of the green method for the production of nanoparticles pulsed laser ablation PLAL that has become increasingly popular. The effect of the nature of the surrounding liquid medium on the size, shape and optical absorption of synthesized nanoparticles prepared by laser ablation of pure copper in different liquids is investigated. The liquid media surrounding the target is thus an important factor affecting the shape, mean size, size distribution and composition of the particles. With the help of Nd: YAG laser with maximum 15mJ energy, pulse duration 10ns and wavelength 1064nm. The ablation of copper target was carried out in distilled water, Ethylene Glycol and Ethyl Alcohol medium, leading to formation of copper and copper oxide nanoparticles of various sizes and shapes. Transmission Electron Spectroscopy TEM, UV-Vis Spectroscopy and Fourier Transform Infrared (FTIR) Spectroscopy were employed for characterization of the particle size, shape and optical properties, respectively. We also compared the synthesized copper nanoparticles in terms of size and stability.
Effect of nitrogen gas concentration on the laser wakefield accelerated electron beams
(UMT, Lahore, 2021) FILZAH PERVEZ
The concept behind the laser-plasma accelerators was first presented in 1979 by Tajima and Dawson. Such accelerators have a great potential to replace the conventional accelerators. They are low-cost, having compact setup and higher acceleration gradient. The acceleration rate is limited in the conventional accelerators by the maximum power of radio-frequency source which eventually causes the electrical breakdown at the metal boundary walls of the accelerators. This can also be overcome by the Laser wakefield accelerators LWFA. When an ultrashort, high intensity, high power laser pulse interacts with the plasma, there arises wake potential until it steepens and breaks. Those electrons which get caught and trapped cause deformation of the wake and stops the further injection of the electrons into the wake. The electrons which surf the wake become accelerated. The quality of the electrons beam accelerated by laser wakefield acceleration is strongly depends on the fact that when and where the injection of the electrons happens in the wake. Several injection techniques have been developed and experimentally demonstrated to control the injection of electrons in the wake and to improve the electron beam quality. One recent method is self-truncated ionization injection which was the most successful to creating low energy spread electron beams has shown encouraging outcomes. The dependence of electron beam quality on the different doping amount of trace gas i.e. different extents of the N2 doping in He gas has been studied in this dissertation. Two dimensional particle-in-cell simulations were performed to get the microscopic view of the distinct phenomena resulting in different beam qualities for different doping of N2. PIC simulations also provided the time resolve evolution of the accelerating structures for different N2 doping. The effect of trace gas doping extent on the self-modulation of the laser pulse is also shown.
Electron Affinity Measurement of Hydrogen Negative Ion by Photodetachment Microscope A Theoretical Study
(UMT, Lahore, 2021) MUHAMMAD USMAN GHANI
In this research work I calculate electron affinity of hydrogen negative ion near a reflecting wall by using the well-known Einstein’s photoelectric effect. A LASER light of certain frequency has been incident on H− and two waves are observed, one is direct wave emitted directly from H− and second is coming back after striking with the reflecting wall called indirect wave. When these waves are superimposed then an interference pattern is observed. It has been observed that the interference pattern not only depends upon electron energy but also the distance between ion and surface. Using theoretical imaging method I study the interference pattern for different incident energies and plot graphs and draw Newton rings by using Matlab coding. Then I derive a linear relation between incident energy and square of number of Newton rings and by plotting this relation, this enables me to calculate the electron affinity of hydrogen negative ion.
Experimental study of graphene oxide−TPPNi nanocomposite based thin film for humidity sensing application
(UMT, Lahore, 2021) Bushra Naveed
Herein this study, we provide improved sensing characteristics, of 5,10,15,20-tetra Phenyl Porphyrinato Nickel (II) (TPPNi) based control humidity sensor. The current experimental study demonstrates that combining TPPNi with graphene oxide (GO) nano-sheets considerably enhances its humidity sensing capability. TPPNi has been synthesized via low temperature & green microwave-assisted synthesis process, whereas, GO has been prepared from graphite powder utilizing Hummer’s method. The structural examination of GO has been performed via FTIR analysis, indicating the successful oxidation of graphite by the presence of oxygenated functional groups. The FESEM surface topographical analysis signifies that GO nanosheets are uniformly distributed and well-attached on TPPNi micropyramidal structures; thereby serving as nanofillers providing a large amount of adsorption/anchoring sites for relative humidity (%RH). The humidity sensing device has been fabricated in a surface-type geometry (Al/TPPNi-GO/Al) and has been electrically characterized at four discrete test frequencies of the AC applied voltage (Vrms ~ 1V): 500 Hz, 1, 10 and 100 kHz. The proposed TPPNi-GO nanocomposite-based device has a capacitive sensitivity of 243.57 pF / %RH @ 500 Hz, which is about 1.67 times higher in comparison with the control TPPNi-based device. The capacitive sensor also has a shorter response time (18 s) and faster recovery time (8 s), accompanied by a wider dynamic range (40 94% RH), as compared to the control device. It is theorized that the superior sensing performance may be linked to the effective diffusion kinetics of water vapours owing to the synergistic enhancement in surface morphology (on the nanoscale), realized by TPPNi-GO nanocomposite.
Magnetic anisotropy energy (MAE) calculations of CuFe2O4
(UMT, Lahore, 2021) Ume Farwa
In this research structural and magnetic properties of spinel ferrite CuFe2O4 are explored with the use of density functional theory with generalized gradient Approximation in wien2k package. We describe these properties in this thesis using full potential linearized augmented plane wave (FP-LAPW) scheme and then make an association with the existing experimental and theoretical data. The calculated structural properties such as lattice parameter, bulk modulus, the derivative of bulk modulus and the ground state energy, are bring into being in outstanding conformity with experimental and theoretical results. The magnetic properties of the CuFe2O4 spinel ferrite also have been calculated. The calculated magnetic anisotropy energies for different crystallographic direction provide us special information and normally we are concerned with the maximum calculated magnetic anisotropy energy. Maximum magnetic anisotropy energy leads us to investigate the easy and hard direction of magnetization and also we recognized the appropriateness of the CuFe2O4 for different magnetic and spintronic applications. The highest energy is in fact the energy that is requisite to switch the magnetization of the crystal from an easy direction to the hard direction.
Natural fiber and titanium dioxide (TiO2) based paper electrode for energy conversion applications
(UMT, Lahore, 2021) RABIYA DILAWAR
Nanotechnology is the field of science, engineering and technology which deals the material at the nanoscale. It has a variety of application in the field of medicine, electronic devices, food industries, air purification, water purification and synthesis of fabrics etc. Nanoparticles of titanium dioxide is synthesis by sol gel method. Sol gel is the most common process to make nanoparticles because it is cost effecient and low temperature process. We can employ Lignocelluloses as substrate as it occurs naturally in abundant and have no bad impacts on environment. In the field of nanotechnology it is observed that titanium dioxide is one of the modern nanomaterials on the basis of catalytic, optical, electronic, spectral and sensing properties. TiO2 is used as pigment in many applications such as sunscreen, wood coatings and printing inks because it absorbs the ultra visible light and it is also used as an active component in solar cell for absorption of solar energy. In this research work the LC/TiO2 based paper electrode is characterized. The results of X-ray Diffraction (XRD) for structural analysis, Scanning Electron Microscopy (SEM) for surface morphology, Cyclic Voltammeter (CV) for electrical properties and Ultraviolet Visible Spectroscopy (UV) for optical properties are used. In this era of advancement the world is moving towards flexible technology. This research work depends on the incorporation of natural fiber in energy conversion devices to achieve green technology based flexible devices.
Optical and surface study of tri-layer thin films prepared by physical vapor deposition
(UMT, Lahore, 2021) Mariyam Mukhtar
Using electron beam evaporation method, multi-layer dielectric/metal/dielectric thin films were produced on cleaned commercial glass substrate. Different metal such as Aluminum (Al), Copper (Cu), and Silver (Ag), have been chosen as intermediate-layer in these three layer nano structure, and Hafnium oxide (HfO2) is serving as insulator material. During fabrication the temperature of substrate was kept at room temperature, and also the overall thickness of these layered devices was 25nm, with Metal, =5nm (inter-layer) and dielectric = 10nm (top layer), and dielectric =10nm (bottom layer). For surface and structural investigation, atomic force microscopy (AFM) and X-ray diffraction (XRD) were utilized. These Dielectric/Metal/Dielectric layer were monoclinic phase with poly-crystalline, according to XRD patterns, with Cu base films having higher crystallinity than Ag or Al. Root mean surface (RMS) are seen in AFM micrograph reveal the smooth surface with low number. A VIS/UR/NIR dual-beam lambda9 spectrometer was used to measure optical characteristics. Better reflection (in infrared region) and transmission (in visible range) might be advantageous for energy-efficient application such as heat mirrors, solar cell among other things. Multiple optical constant such as extinction coefficient, energy losses, molar resistivity and refractive index among other have been computed using observed transmission and reflection.
Photocatalytic degradation of Methyl Green dye mediated by pure and Mn-doped Zinc Oxide nanoflakes under solar light irradiation
(UMT, Lahore, 2021) ADEENA FATIMA
ABSTRACT Water pollution crises, which humanity is facing as a result of the rapid industrial revolution, increasing urbanization, and a burgeoning human population, necessitate a highly efficient, economical, easily accessible, eco-friendly, and long-term green solution to support the sustainable development of smart cities. The most significant source of water pollution is the extensive discharge of untreated industrial wastewater, especially when it is primarily made up of synthetic organic dyes (diazo and cationic dyes). Herein this study, pure and Mn-doped ZnO (2 wt.%) nanoparticles have been synthesized using the chemical precipitation method and characterized for photodegradation of methyl green pollutant dye. The structural analysis via XRD patterns has revealed that both intrinsic and Mn-doped ZnO (2 wt.%) samples have hexagonal wurtzite structure with appropriate phase, clearly indicating the absence of any impurity. The incorporation of manganese in the host ZnO lattice has decreased the crystallite size (21.10 → 18.76 nm) and Nano flakes type features with sizes in the 50 – 100 nm range have been observed through FESEM based surface morphological studies, both observations have merit in providing more active area and high surface area to volume ratio for photocatalytic reaction. The investigation of photophysical properties indicates that in Mn-doped ZnO nanoparticles, the absorption peak is blue-shifted by 5 nm (365 → 360 nm), due to the widening of the bandgap. The photocatalytic activities of the as-synthesized pure and Mn-doped ZnO photocatalysts have been evaluated by the degradation of MG pollutant dye in aqueous solutions under natural sunlight. The degradation of MG dye the photocatalysts follow the pseudo-first-order kinetics with relatively quasi-linear regression coefficient. Specifically, the efficiency has been calculated to be 62.78% for pure ZnO and 66.44% for Mn-doped–ZnO (2 wt. %) under 60 minutes sunlight irradiation. The rate of photocatalytic reaction (K) ~ 0.01477 min-1 and R2 ~ 0.92164 has been achieved for pure ZnO, whereas slightly higher ~ 0.01617 min-1 and R2 ~ 0.93494 has been observed for Mn-doped ZnO, respectively. Conclusively, the synergistic interactions with multiple charge transfer pathways, improvement of e−/h+ pair charge separation and efficient generation of hydroxyl radicals are supposed to be responsible for the high efficient photocatalytic activity of the Mn–doped ZnO photocatalyst for MG dye.
Preparation of 2D-WSE2 structures by salinization of WO3 thin films for hydrogen generation
(UMT, Lahore, 2021) Muhammad Bilal
Recently, researchers have focused on ultrathin films of 2-D materials because of the interesting features they exhibit in compared to their bulk counterparts. The properties and processing of graphene have been the primary focus of this field's research for many years, but recently, researchers have begun to shift their focus to other two-dimensional material systems, such as hexagonal boron nitride (h-BN) and the transition metal dichalcogenide (TMD) compounds. These compounds are fascinating for a variety of applications, from tunneling field effect transistors (TFETs) to hydrogen evolution catalysts, because of their unique combination of optical, electrical, thermal, and chemical characteristics. Tungsten diselenide (WSe2) has been getting a lot of interest as of late because to its direct band gap in the visible spectrum, which has the potential to be used in a variety of technological applications. This thesis, however, aims to develop wafer-scale WSe2 since the aforementioned exploration is not currently handled at a sufficiently big scale for hydrogen generation using water splitting. Under an argon gas carrier, tungsten diselenide films were produced through chemical vapour deposition via salinization of a tungsten oxide WO3 film deposited via thermal vapour deposition. Research into the effects of selenium overpressure, reaction temperature, system pressure, heat treatment, substrate, and oxide film treatment on film growth was carried out. Photo spectroscopy, scanning electron microscopy (SEM), Potentiostat (PEC), and X-ray diffraction were used to analyses the films. It was discovered that WSe2 could be generated by the batch synthesis method under a variety of experimental settings; however, the highest results of current were achieved at temperature 800 °C, with argon carrier gas ratio.
Preparation of ZnO/Ag/ZnO, ZnO/Al/ZnO, SnO2/Ag/SnO2, SnO2/Al/SnO2 multilayer structures as transparent conducting oxide
(UMT, Lahore, 2021) Rasheed Ul Hassan
Indium doped tin oxide (ITO) are commercially available as transparent conducting oxide and it is commonly used as a front contact in solar cell, flat panel display, organic light emitting diodes, and conducting substrate in photocatalysis. Unfortunately, Indium is a rare earth metal, and it cannot meet the requirements of the industry. ZnO/Ag/ZnO, ZnO/Al/ZnO, SnO2/Ag/SnO2, SnO2/Al/SnO2 multilayered Structures were prepared by sol gel spin coating and thermal evaporation techniques as transparent conducting substrates. XRD results showed that ZnO and SnO2 films were polycrystalline. Optical properties of all prepared samples were measured by spectrophotometry. It was observed that multilayer structures showed average transmittance above 65% the visible region. Electric properties results showed that ZnO/Ag/ZnO and SnO2/Ag/SnO2 multilayer have resistivity 1.94 ×10-4 ohm-cm and 1.37 × 10-5 ohm-cm which is comparable with the commercially available indium doped tin oxide (ITO) substrate.
Study of spectrum of charmonium and bottomonium
(UMT, Lahore, 2021) HINA RIAZ
In this work we review about Particle Physics basics. We discuss about Standard model in which we talk about fundamental particles and fundamental interactions. After the discussion of Standard model, we solve the radial part of Schrödinger equation numerically. We also talk about Cornell potentials. To calculate the states of charmonium and bottomonium we numerically solve radial equation using a non-relativistic potential model. To deal with 1 r3 ⁄ we introduced a cutoff parameter because the wave function at origin becomes oscillatory. We calculate the states of heavy meson.
Study of structural, morphological & magnetic properties of Ba doped bismuth ferrite (BiFeO3)
(UMT, Lahore, 2021) Shayan Fatima
In the last two decades, strong polarization, different multiple phases, and very good response, perovskites-based ferroelectric are getting importance. The main reason for the popularity is its, spontaneous polarization which occurred below the Curie temperature. And by using external magnetic field, it can be switched. Here, I report a phase pure synthesis of BiFeO3 using, sol-gel method. We enhanced the crystal structure by calcination of the prepared samples at 650oC for 2 hours. Structural studies show the formation of single-phase perovskite (BiFeO3) in X-ray diffraction. We investigate the magnetic properties of samples, which are coercivity(Hc), saturation magnetization(Ms) & remnant magnetization(Mr) using a vibrating sample magnetometer(VSM). To investigate the surface geomorphology, we used the scanning electron microscope(SEM) operated at 10 KV. These results indicate strong modification in the surface structure, due to an increase in the doping concentration of barium.
Synthesis and application of cu-doped zinc oxide Zn1-xCuxO (x = 0.01, 0.02, 0.03, 0.04, 0.05) based microstructures for the elimination of methylene blue dye pollutant under sunlight
(UMT, Lahore, 2021) Umair Khalid
Herein, copper (Cu) doped zinc oxide (ZnO) namely Zn1-xCuxO (x = 0.01, 0.02, 0.03, 0.04, 0.05) microstructures are synthesized by hydrothermal method for photocatalytic activity. The grown samples were characterized with XRD, FTIR, SEM and UV-vis. The XRD results confirmed the successful doping of Cu ions without altering the basic hexagonal structure of ZnO. FTIR results also confirm the presence of metal-oxygen bond vibration related to Zn-O bonds. UV-vis results showed that the energy bandgap decreased with the increase in the doping concentration of Cu in the ZnO host. Photocatalytic activities of all synthesized samples were tested against methylene blue (MB) dye under sunlight irradiation. The Zn0.95Cu0.05O photocatalyst has shown the best photocatalytic activity with 99.9% elimination of MB dye within 60 min, as compared to the pure ZnO and 1%, 2%, 3%, and 4% Cu doped ZnO. In comparison to the other catalyst, the value of the rate constant for Zn0.95Cu0.05O has been observed to be greater. The excellent photocatalytic activity of Zn0.95Cu0.05O is accredited to, 1) the presence of Cu ions that successfully suppress high recombination of electron-hole pair which, in turn, find enough time to produce extra reactive species for degradation MB dye and 2) Lower energy bandgap of ZnO by 5% Cu doping in visible region which leads to a higher number of electrons excitation from valence band to conduction band. Hence, the present finding introduces a strategy to reduce the energy bandgap of ZnO from UV to the visible region to make it efficient for practical photocatalytic applications under sunlight.
Synthesis and characterization of natural fiber/tungsten oxide nanostructure based paper electrode for smart window applications
(UMT, Lahore, 2021) AYESHA FAROOQ
Flexible electrodes are of great fascination in the modernity of smart technology for the application of countless energy conversion as well as energy storage devices such as lithium-ion batteries, solar cells and thin film transistors. For adaptable, flexible high tech gadgets, addressing the hereditary structure of metal oxide is incredibly effective. Traditional electrodes are inferior then flexible metal oxide-based paper electrodes on the basis of their environmental friendliness, variety, and nontoxicity. The addition of insulating natural fibers in paper electrodes, on the other hand, limits conductive characteristics. In the present work, hydrothermal method was used to modify the conductivity characteristics of lignocellulose (natural fibers) and tungsten oxide (WO3) based paper electrodes. The produced flexible and electronically conductive paper electrodes were characterized in detailed using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Cyclic Voltammetry (CV) and Ultraviolet-Visible (UV-Vis) Spectroscopy. The effective production of Tungsten Oxide (WO3) is confirmed by X-Ray diffraction (XRD), while the nanostructured geometry can be seen in the scanning microscopy (SEM). The composite formation was confirmed using Fourier Transform Infrared (FTIR), and cyclic voltammetry (CV) calculations were taken on all of the synthesized samples to investigate the electrochemical kinetics, with LC/WO3 exhibiting the best specific capacitance of 38.2μF/g. The optical band gap (2.58eV) of LC/WO3 is determined by using UV-Vis Spectroscopy. Because of their light weight, environmental friendly and improved electrochemical characteristics, these manufactured composites can be employed as flexible electrodes in energy storage applications and will be ideal for modern bendable and disposable energy storage systems.
Synthesis and characterization of pristine and Sr-doped ZnO nanostructures for methyl green photodegradation application
(UMT, Lahore, 2021) ADEELA BASHIR
The present work describes an effective route for degradation and de-colorization of methyl green (MG) dye by pristine and Strontium (Sr) doped Zinc oxide (ZnO) photocatalysts under visible light. The pair of ZnO and Sr-ZnO photocatalysts have been synthesized by the chemical precipitation method. The structural analysis using X-ray diffractometer has experimentally confirmed that both photocatalysts exhibit the hexagonal wurtzite structure, without any additional phase formation in Sr-doped ZnO, in particular. However, interestingly the doping with Sr2+ cation has caused a slight shift in the XRD peaks toward lower diffraction angles, which may be sourced by a slender increase in the lattice parameters. The crystallite size and internal strain for both photocatalysts have been calculated using Williamson-Hall plot. The optical properties of the synthesized photocatalysts have been investigated using UV–vis absorption spectroscopy in the wavelength range ~ 250-800 nm. As observed in Tauc’s plot, the slight decrease from 3.3 to 3.2 eV in band gap energy in case of Sr-doped ZnO may be due to formation of sub-band level between valence and conduction band caused by the impregnation of Sr2+ ions in the ZnO host. The morphological study has also been performed by using FESEM, which indicates nanoflakes (NFs) based surface texture. During the photocatalytic activity study, after 30 minutes irradiation of visible light, ~65.7% and ~84.8% photocatalytic degradation of MG aqueous solution has been achieved for Sr-doped (2 wt.%) and pristine ZnO photocatalyst, respectively. The rate of photocatalytic reaction (K) has been observed to be ~ 0.06399 min-1 for Sr-doped (2 wt.%), whereas nearly half magnitude ~ 0.03403 min-1 has been observed with pristine ZnO, respectively. The better photodegradation activity may be ascribed to the relatively broader optical absorption capability and the enhanced charge separation efficiency of the Sr-doped ZnO photocatalyst.

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