metal-oxide-heterojunction-for-photocatalytic-activities

Metal Oxide Heterojunction for Photocatalytic Activities

There is a significant global demand for improvements in synthesis techniques and their optimal characteristics, especially for industrial-scale ...

Adama Science and Technology University

Electrical porcelain insulator was fabricated from local ceramic raw materials, Bombowha kaolin/clay, Arero feldspar and Arero quartz available in Ethiopia. The raw materials mineralogy, chemical composition, and thermal properties were characterized by using x-ray diffractometer (XRD), atomic absorption spectrometer (AAS) and thermogravimetry (TGA), respectively. Plasticity of clay was determined according to Atterberg plasticity test. Based on the raw materials chemical composition, five different porcelain insulator test bodies were prepared at firing temperature of 1000 °C, 1100 °C, 1200 °C and 1300 °C. Water absorbance, apparent porosity, bulk density, dielectric strength and microstructure of fired porcelain insulators were studied as a function of firing temperature. The XRD and AAS results revealed that in Bombowha clay, kaolinite mineral was found to be a major mineral constituent with appreciable silica (46.84 wt%) and alumina (36.74 wt%) content with moderate plasticity (PI = 19-21%). The Arero feldspar belongs to anorthoclase feldspar minerals with less alkali content (NaO + K0) of <7wt %. Among the tested porcelain insulator bodies, the test body with composition of 45% kaolin, 45% feldspar and 10 % quartz exhibited superior properties of having a water absorbance of 0.010%, porosity of 0.088%, density of 2.466 g/cm, dielectric strength of 8 Kv/mm at firing temperature of 1300 °C with mullite and quartz phase embedded in sufficient glassy phase. Therefore, the experimental result confirmed that standard porcelain insulator can be fabricated from locally available ceramic raw materials (clay and quartz) in Ethiopia at optimized condition.

Fabrication of electrical porcelain insulator from ceramic raw materials of Oromia region, Ethiopia.

This work reveals a green combustion route for the synthesis of TiO, FeO and TiO-FeO nanocomposites as photocatalysts for decolorization of Titan Yellow (TY) and Methyl Orange (MO) dyes at room temperature in aqueous solution concentration of 20 ppm under UV-light irradiation. We observed that the TiO-FeO nanocomposite shows superior photocatalytic activity for TY dye compared to pure TiO and FeO. Rate constant (k) values of TiO, FeO and TiO-FeO for TY and MO are 0.0194, 0.0159, 0.04396 and 0.00931, 0.00772 0.0119 kmin respectively. The surface area and pore volume of TiO-FeO nanocomposite were found to be 71.56 m/g and 0.076 cm/g, respectively as revealed by BET studies. From the Barrett-Joyner-Halenda (BJH) plot, the mean pore diameter of TiO-FeO nanoparticles was found to be 2.43 nm. Further, the TiO-FeO nanocomposite showed good electrochemical behavior as an electrode material for supercapacitors when compared to pure TiO and FeO nanoparticles resulted in stable electrochemical performance with nearly 100% coulombic efficiency at a scan rate of 10 mV/s for 1000 cycles. Interestingly, the novelty of this work is that the designed supercapacitors showed stable electrochemical performance even at 1000 cycle, which might be useful for rechargeable supercapacitor applications. The electrochemical properties of the nanocomposites were compared by the data obtained by cyclic voltammograms, charge-discharge tests and electrochemical impedance spectroscopic studies. These results demonstrated that the TiO-FeO nanocomposite showed stable performance compared to TiO and FeO nanoparticles at current density of 5 Ag.

Enhanced photocatalytic and electrochemical performance of TiO-FeO nanocomposite: Its applications in dye decolorization and as supercapacitors.

Metal oxide nanomaterials are one of the preferences as antibacterial active materials. Due to its distinctive electronic configuration and suitable properties, ZnO is one of the novel antibacterial active materials. Nowadays, researchers are making a serious effort to improve the antibacterial activities of ZnO by forming a composite with the same/different bandgap semiconductor materials and doping of ions. Applying capping agents such as polymers and plant extract that control the morphology and size of the nanomaterials and optimizing different conditions also enhance the antibacterial activity. Forming a nanocomposite and doping reduces the electron/hole recombination, increases the surface area to volume ratio, and also improves the stability towards dissolution and corrosion. The release of antimicrobial ions, electrostatic interaction, reactive oxygen species (ROS) generations are the crucial antibacterial activity mechanism. This review also presents a detailed discussion of the antibacterial activity improvement of ZnO by forming a composite, doping, and optimizing different conditions. The morphological analysis using scanning electron microscopy, field emission-scanning electron microscopy, field-emission transmission electron microscopy, fluorescence microscopy, and confocal microscopy can confirm the antibacterial activity and also supports for developing a satisfactory mechanism. Graphical abstract showing the metal oxides antibacterial mechanism and the fluorescence and scanning electron microscopic images.

A Review on Enhancing the Antibacterial Activity of ZnO: Mechanisms and Microscopic Investigation.

Zinc oxide (ZnO) is a fascinating semiconductor material with many applications such as adsorption, photocatalysis, sensor, and antibacterial activities. By using a poly (vinyl alcohol) (PVA) polymer as a capping agent and metal oxides (iron and manganese) as a couple, the porous PVA-aided Zn/Fe/Mn ternary oxide nanocomposite material (PTMO-NCM) was synthesized. The thermal, optical, crystallinity, chemical bonding, porosity, morphological, charge transfer properties of the synthesized materials were confirmed by DTG/DSC, UV-Vis-DRS, XRD, FT-IR, BET, SEM-EDAX/TEM-HRTEM-SAED, and CV/EIS/amperometric analytical techniques, respectively. The PTMO-NCM showed an enhanced surface area and charge transfer capability, compared to ZnO. Using the XRD pattern and TEM image analysis, the crystalline size of the materials was confirmed to be in the nanometer range. The porosity and superior charge transfer capabilities of the PTMO-NCM were confirmed from the BET, HRTEM (IFFT)/SAED, and CV/EIS analysis. The adsorption kinetics (adsorption reaction/adsorption diffusion) and adsorption isotherm test confirmed the presence of a chemisorption type of adsorbate/methylene blue dye-adsorbent/PTMO-NCM interaction. The photocatalytic performance was tested on the Congo red and Acid Orange-8 dyes. The superior ascorbic acid sensing capability of the material was understood from CV and amperometric analysis. The noble antibacterial activities of the material were also confirmed on both gram-negative and gram-positive bacteria.

Multifunctional application of PVA-aided Zn-Fe-Mn coupled oxide nanocomposite.

Zinc oxide is one of the novel metal oxides utilized for diverse applications. The sol-gel and unintended self-propagation procedures were applied to synthesize the porous and high surface area ZnO-based metal oxide nanocomposite. The p-type manganese(III) oxide was successfully coupled with n-type ZnO The physical property characterization results revealed the surface area, porosity, and charge transfer capability improvement on the poly(vinyl alcohol) (PVA)-aided binary nanocomposite (PVA-ZnO/MnO), compared to ZnO. The XRD patterns and TEM image analysis validated the nanometer size range for the materials (15-60 nm). The SEM micrographs and BET spectral details have confirmed the porous nature of the PVA-ZnO/MnO nanocomposite. The supporting results were obtained from the HRTEM (IFFT) and SAED pattern analyses. The EDX and HRTEM analyses were used for the confirmation of elemental composition and reality of the PVA-ZnO/MnO composite, respectively. The presence of the improved charge transfer property for PVA-ZnO/MnO, compared to ZnO, was evidenced from acid orange-8 dye degradation. The highest zone of inhibition (14 mm) was recorded on  bacteria for the uncalcined PVA-ZnO/MnO nanocomposite compared to PVA, yet, less zone of inhibition compared to the calcined PVA-ZnO/MnO nanocomposite. The authors recommend the formation of the couple between metal oxides by electrochemical technique analyses as a future work.

Synthesis of Poly(vinyl alcohol)-Aided ZnO/MnO Nanocomposites for Acid Orange-8 Dye Degradation: Mechanism and Antibacterial Activity.

The aim was to formulate and evaluate Gel/PVA hydrogels as a pH-sensitive matrix to deliver methotrexate (MTX) to colon. The primed Gel/PVA hydrogels were subjected to evaluation for swelling behavior, diffusion coefficient, sol-gel characteristic and porosity using an acidic (pH 1.2) and phosphate buffer (PBS) (pH 6.8 & pH 7.4) media. Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) were performed to evaluate the chemical compatibility of the Gel/PVA hydrogel. The shape alteration and release of Gel/PVA hydrogel was conducted at pH 1.2, pH 6.8 and pH 7.4. The drug release kinetic mechanism was determined using various kinetic equations. The physicochemical evaluation tests and drug release profile results were found to be significant ( < 0.01). However, it was dependent on the polymers' concentration, the pH of the release media and the amount of the cross-linking agent. Hydrogels containing the maximum amount of gel showed a dynamic equilibrium of 10.09 ± 0.18 and drug release of 93.75 ± 0.13% at pH 1.2. The kinetic models showed the release of MTX from the Gel/PVA hydrogel was non-Fickian. The results confirmed that the newly formed Gel/PVA hydrogels are potential drug delivery systems for a controlled delivery of MTX to the colon.

Methotrexate-Loaded Gelatin and Polyvinyl Alcohol (Gel/PVA) Hydrogel as a pH-Sensitive Matrix.

The dysfunctioning of β-cells caused by the unspecific misfolding of the human islet amyloid polypeptide (hIAPP) at the membrane results in type 2 diabetes mellitus. Here, we report for the first time, the early-stage interaction of hIAPP oligomers on the DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) lipid membrane using electrochemical parameters. Electrochemical techniques are better than other techniques to detect hIAPP at significantly lower concentrations. The surface level interactions between the peptide (hIAPP) and lipid membrane (DMPC) were investigated using atomic force microscopy (AFM), confocal microscopy (CM) and electrochemical techniques such as Tafel polarization, cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Inserting IAPP into the fluid domains results in breaking the lipid-to-lipid interaction, leading to restriction of membrane mobility. The S values of the liposome and IAPP co-solubilized liposome indicates the cooperative insertion of IAPP. Further, a new method of immobilizing a membrane to the gold surface has been employed, resulting in an electrical contact with the buffer, preventing the direct utilization of a steady-state voltage across the bilayer. The electrochemical studies revealed that the charge transfer resistance decreased for 3-mercaptopropanoic acid modified gold (MPA-Au) electrode coated with the liposome and after the addition of IAPP, followed by an increase in the capacitance. The present study has opened up new dimensions to the understanding of peptide-membrane interactions and shows different experimental approaches for the future researchers in this domain.

Early-stage culprit in protein misfolding diseases investigated using electrochemical parameters: New insights over peptide-membrane interactions.

Medicinal plants and essentials oils are well known for diverse biological activities including antidiabetic potential. This study was designed to isolate essential oils from the leaves of  L. (), perform its phytochemical analysis, and explore its in vitro antidiabetic effects.

Phytochemical Analysis, -Glucosidase and Amylase Inhibitory, and Molecular Docking Studies on  L. Leaves Essential Oils.

Green synthesis of metal oxide nanoparticles (NPs) is a viable alternative methodology because of cost-effective and availability of environmentally friendly templates for desired application, which has attracted the attention of researchers in recent years. In the present study, CoO NPs were synthesized in various volume ratios in the presence of  leaf extract as a template. The synthesized CoO NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), surface area electron diffraction (SAED), UV-Vis diffuse reflectance spectroscopy (UV-DRS), and Fourier transform infrared (FTIR) spectroscopy. XRD analysis found that the average crystalline sizes for the 1 : 2, 1 : 1, and 2 : 1 volume ratios was 25.83, 21.05, and 27.98 nm, respectively. SEM-EDX and TEM analyses suggest that the green-synthesized CoO NPs are spherical in shape without the presence of impurities. The band gap   values of the 1 : 2, 1 : 1, and 2 : 1 volume ratios of CoO NPs were found to be 1.83, 1.77, and 2.19 eV, respectively. FTIR analysis confirmed the presence of various bioactive ingredients within the leaf extract of . CoO NPs-modified electrodes showed better sensing capability towards ascorbic acid and citric acid due to enhanced electron transfer kinetics. Among three volume ratios (1 : 2, 1 : 1, and 2 : 1) of CoO nanoelectrodes, 1 : 1 and 2 : 1 were identified as the best performing nanoelectrodes. This is possibly due to the high catalytic behavior and the more homogenized surface structure. CoO (1 : 2) nanodrug showed the enhanced antibacterial activity (16 mm) towards  which is attributed to the formation of enhanced reactive oxygen species (ROS).

 Leaf Extract Templated Synthesis of CoO Nanoparticles for Electrochemical Sensor and Antibacterial Applications.

Colloidal nanocrystals play a vital role in several applications. The doping of cations in the nanocrystal matrix enhances the optical, electrical, and magnetic properties. The number and well-defined distribution of the dopant are crucial to protect the nanocrystal from clustering. The XRD, XPS, and XAS instruments reveal the change in the lattice parameters, chemical states, and local coordination environment information. In addition of detecting the position and distribution of the dopant, the 4D-STEM detector mode gathers all types of real-space atomic-resolution images by collecting all diffraction datasets from each electron probe with high-speed and efficient detection. Dopant-host ligand type, reactions conditions, and reaction time optimization during synthesis are critical for the host and dopant reactivity balance. Pearson's hard/soft acids/bases theory would be a base for balancing the solubility of the dopant-host in the given solvents/surfactant. In addition, tuning the colloidal nanocrystals to secondary structures, which enhances the mass-/ions transport, can contribute a combination of properties that do not exist in the original constituents.

Insights into ZnO-based doped porous nanocrystal frameworks.

Gastric ulcer induced by NSAIDs is the major medical concern and researchers are utilizing several approaches to combat this medical issue. In the current study, we investigated the efficacy of thiadiazinethione derivative (2,2'(2-thioxo-1,3,5-thiadiazinane-3,5-diyl) diacetic acid, as new less ulcerogenic compound.

Analagesic and Anti-Inflammatory Potentials of a Less Ulcerogenic Thiadiazinethione Derivative in Animal Models: Biochemical and Histochemical Correlates.

Valvular heart disease (VHD) is a major contributor to loss of physical function and longevity. Oxidative stress is one of the key causative factors involved in heart disease including VHD. Here, we aimed to illuminate the role and relation of oxidative stress to the VHD risk markers in the human population.

Article	Year
Fabrication of electrical porcelain insulator from ceramic raw materials of Oromia region, Ethiopia. Heliyon\| PubMed ID: 31485525	2019
Enhanced photocatalytic and electrochemical performance of TiO-FeO nanocomposite: Its applications in dye decolorization and as supercapacitors. Scientific reports\| PubMed ID: 31988344	2020
A Review on Enhancing the Antibacterial Activity of ZnO: Mechanisms and Microscopic Investigation. Nanoscale research letters\| PubMed ID: 33001404	2020
Multifunctional application of PVA-aided Zn-Fe-Mn coupled oxide nanocomposite. Nanoscale research letters\| PubMed ID: 33387075	2021
Synthesis of Poly(vinyl alcohol)-Aided ZnO/MnO Nanocomposites for Acid Orange-8 Dye Degradation: Mechanism and Antibacterial Activity. ACS omega\| PubMed ID: 33458547	2021
Methotrexate-Loaded Gelatin and Polyvinyl Alcohol (Gel/PVA) Hydrogel as a pH-Sensitive Matrix. Polymers\| PubMed ID: 34301057	2021
Early-stage culprit in protein misfolding diseases investigated using electrochemical parameters: New insights over peptide-membrane interactions. Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie\| PubMed ID: 34329823	2021
Phytochemical Analysis, -Glucosidase and Amylase Inhibitory, and Molecular Docking Studies on L. Leaves Essential Oils. Evidence-based complementary and alternative medicine : eCAM\| PubMed ID: 35096118	2022
Leaf Extract Templated Synthesis of CoO Nanoparticles for Electrochemical Sensor and Antibacterial Applications. Bioinorganic chemistry and applications\| PubMed ID: 35308018	2022
Insights into ZnO-based doped porous nanocrystal frameworks. RSC advances\| PubMed ID: 35424565	2022
Analagesic and Anti-Inflammatory Potentials of a Less Ulcerogenic Thiadiazinethione Derivative in Animal Models: Biochemical and Histochemical Correlates. Drug design, development and therapy\| PubMed ID: 35478935	2022
C-Reactive Protein and High-Sensitive Cardiac Troponins Correlate with Oxidative Stress in Valvular Heart Disease Patients. Oxidative medicine and cellular longevity\| PubMed ID: 35535358	2022

H. C. Ananda Murthy

Biography

JoVE Journal Publications

Other Publications