Sharif Digital Repository

Nowadays, there is a growing interest in synthesizing electrodes used in zinc electrowinning, increasing active surface area, decreasing specific energy consumption, and the oxygen evolution reaction (OER) overpotential. In this study, modified nanocomposite anodes were synthesized by applying pulsed and constant direct current electrodeposition to improve the catalytic activity of the electrodes toward the oxygen evolution reaction (OER) and reduce energy consumption in zinc electrowinning. By decreasing particle size, the active surface area of PbO2-RuO2 nano-mixed composite electrode was 2.88 and 14.22 times greater than PbO2-RuO2 microcomposite and pure PbO2 electrodes, respectively.... 

A hierarchical superhydrophobic surface is prepared via a two-step boiling water immersion process and anodization of the treated aluminum substrate in a novel hydrophobic electrolyte of aluminum nitrate and stearic acid mixture at room temperature. The immersion time in boiling water had a significant influence on the morphology and durability of the sample. A pseudoboehmite coating is created on the aluminum surface during the boiling process, as revealed by the field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) spectrophotometer results. The energy-dispersive x-ray spectroscopy analysis confirmed the formation of hydrophobic coating surface after... 

In this research, different coating methods of polyaniline (PANI) on the anode electrodes and their performance in microbial fuel cells (MFCs) were investigated. The performance of systems in a discontinuous state was studied using the high energy content dairy industry wastewater. The phase enrichment assessment was conducted under open circuit potential (OCP) and the performance of MFCs coated with PANI through three methods was evaluated via chemical oxygen demand (COD), polarization, power density, energy coulombic efficiency (ECE), coulombic efficiency (CE), and potential efficiency (PE) values. The results showed the maximum value for the power density of 28Wm-3, CE of 17%, and COD of... 

In this study, the different parts of carthamus tinctorius plant, including petal (SPE), leaf (SLE), and shoot (SSE), have been extracted. Adsorption of the extracts on mild steel in 3.5 wt. % NaCl solution was evaluated employing electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and electrochemical noise measurements (EN). The field-emission scanning electron microscopy (FE-SEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were employed to appraise the morphology of the samples surface subjected to the test solutions. According to the EIS results, the maximum adsorption efficiency belonged to the solution containing 1 g L−1 of... 

We conduct an experimental investigation on the pool boiling enhancement in DI water on nanoporous surfaces. The surfaces are modified by anodic oxidation, and cavities with 2 mm diameter and pitches between 2.5 and 5 mm applied on them using EDM method filled with a two-part epoxy with low thermal conductivity properties. The capillary wicking action of the superhydrophilic nanoporous oxide layer enhances the rewetting and spreading of the liquid to dry-spots during boiling. The epoxy disks remain wet and prevent merging bubbles during the pool boiling experiment and a 2-D microflow is induced toward dried regions with synergic effects of nanoporous surface absorption, create a considerable... 

Room temperature gas sensing behavior of arrayed one-dimensional (1D) nickel nanowires (Ni NWs) are investigated using impedance spectroscopy. Ni nanowires synthesized via electrochemical deposition method based on anodic aluminum oxide (AAO) templates. Their structural characterization verified by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) analysis. Impedance spectroscopy as an essential technique utilized to understand the mechanism of gas interaction with the wires through the changes in their electronic behavior. Bode and Nyquist plots with the real and imaginary impedances are plotted versus frequency range of 500 Hz... 

Two main origins of failure for hard tissue replacements are structural loosening and prosthetic implant infections (PIIs). Bioinspired multifunctional TiO2 hierarchical micro/nanostructures of conical-shaped TiO2 (CTO), regular TiO2 nanotubes (RTO) and irregular TiO2 nanotubes (ITO) with tunable improved cell growth and inhibited bacteria adhesion were synthesized. CTO and ITO samples indicated superhydrophilicity with contact angles of less than 5°. The MTT assay demonstrated excellent biological performance for RTO and CTO sample with 98.1% and 103.1% of cell viability, respectively. The bridging force for osteoblast cell attachment onto the synthesized porous coatings was presented as a... 

This study aimed to prepare nanoporous anodic alumina on AA3003-H14 aluminum alloy using a mild anodization process with minimal working voltage and treatment time. The microstructural features, mechanical properties, and tribocorrosion behavior of the coatings were assessed to determine the optimum conditions for the fabrication of nanoporous anodic alumina on AA3003-H14 alloy. The microstructural analysis showed both uniform and nonuniform pore nucleations during anodization in H2SO4/C2H2O4, H2SO4/H2CrO4, and EG/H2O/NH4F electrolytes, where the optimal nanoporous structure with an average thickness, porosity, pore diameter, and interpore distance of 382 nm, 19%, 16 nm, and 35 nm,... 

Nanomedicine has seen a significant rise in the development of new research tools and clinically functional devices. In this regard, significant advances and new commercial applications are expected in the pharmaceutical and orthopedic industries. For advanced orthopedic implant technologies, appropriate nanoscale surface modifications are highly effective strategies and are widely studied in the literature for improving implant performance. It is well-established that implants with nanotubular surfaces show a drastic improvement in new bone creation and gene expression compared to implants without nanotopography. Nevertheless, the scientific and clinical understanding of mixed oxide... 

Urea is a major source of nitrogen pollution in domestic sewage and its denitrification is difficult since it is very likely to be converted into ammonia or nitrate instead of expected N2. Herein, we propose an exhaustive denitrification method for urea via the oxidation of amine/ammonia-N with chlorine oxide radical, which induced from a bi-functional RuO2//WO3 anode, and the highly selective reduction of nitrate-N on cathode in photoelectrochemical cell (PEC). Under illumination, the WO3 photoanode side promotes the quantities hydroxyl and reactive chlorine radical, and these radicals are immediately combined to stronger chlorine oxide radical by RuO2 side, which obviously enhances the... 

Titanium type lithium ion-sieve nanotubes synthesized by the hydrothermal method were extensively explored over recent years due to its promising properties. However, on account of nanotubes′ tangled structure impeding the lithium adsorption in the interior nanotube walls, unalterable dimensions of the synthesized nanotubes, and a long period of annealing, the anodizing technique was proposed. It is shown that lithium uptake and adsorption capacity is improved because of easier mass transfer during the ion exchange process. This work focuses on a novel anodizing method for nanotube ion-sieve synthesis. The optimum anodizing condition was discovered by altering anodizing voltage, time, and... 

In this study, a two-phase flow model based on species transport, energy, and electrochemical equations was developed for polymer electrolyte membrane fuel cell (PEMFC). The influences of heat sources and sinks, and water transport inside the fuel cell were also taken into account. In this regard, the effect of the operating conditions including cell temperature and pressure, anode and cathode inlet humidity, and anode and cathode stoichiometric ratios on the fuel cell performance was investigated. The simulation results show that inlet humidity and stoichiometric ratio of the anode side, cell pressure and temperature, and distribution of the heat sources and sinks are crucial factors... 

A novel electrode consisting of 3D porous nickel‒cobalt‒copper sulfide dendritic structures is synthesized, in which, for the first time ternary Ni–Co–Cu foam is constructed through hydrogen bubble template and followed by sulfidization via a hydrothermal reaction in thiourea. The 3D, porous Ni–Co–Cu dendritic sulfide electrode exhibits a high specific capacitance of 1203.75 F g−1 (0.963 F cm−2) at current of 1.0 mA and excellent cycling stability, excellent ratability along with high cycle stability. An asymmetric supercapacitor (ASC) using dendritic sulfide structures and reduced electro-etched carbon fiber paper (RECF) as the positive and negative electrodes, respectively is developed.... 

In this study, apatite formation ability on TiO2 nanotubes (TNTs) synthesized by anodizing process were compared with TNTs decorated by MnO nanoparticles. The MnO nanoparticles used for decoration process were fabricated via thermal decomposition method. At first, it was strived to find the optimal condition of anodizing process and the effect of applied voltages (15 V, 20 V, and 25 V) and process times (15 min, 20 min, and 25 min) on the diameter of the synthesized TNTs was investigated. Results of microscopic characterizations showed that the completely uniform structure of nanotubes with a diameter in the range of about 100–130 nm was achieved after 20 min of anodizing process at an... 

Here, controlled growth of vertically aligned carbon nanotubes (VACNTs) on free-standing porous activated reduced graphene oxide (a-rGO) paper was fabricated using plasma-enhanced chemical vapor deposition method. The electrochemical performance of prepared film was investigated to provide effective electrode for 3D flexible high-performance lithium-ion batteries (LIBs) and supercapacitors. The results revealed that the prepared electrode exhibited a high specific capacitance of 347 F/g at 0.5 A/g in 1 M KOH electrolyte, 60% more than non-activated rGO-paper (218 F/g). The VACNTs on a-rGO have increased the accessible surface area and acted as efficient electrical conducting paths, which... 

Supercapacitors store charge by ion adsorption or fast redox reactions on the surface of porous materials. One of the bottlenecks in this field is the development of biocompatible and high-rate supercapacitor devices by scalable fabrication processes. Herein, a Ti-rich anatase TiO2 material that addresses the above-mentioned challenges is reported. Tubular nanolettuces were fabricated by a cost-effective and fast anodization process of Ti foil. They attained a large potential window of 2.5 V in a neutral electrolyte owing to the high activation energy for water splitting of the (1 0 1) facet. Aqueous and all-solid-state devices showed diffusion time constants of 46 and 1700 ms, as well as... 

A high performance asymmetric supercapacitor (ASC)has been fabricated by using nickel oxide-cobalt oxide nanosheets (NiO–CoO NSs), which were directly grown on carbon nanotubes (CNTs)and hydrothermal carbon spheres (HTCs)as positive and negative electrodes, respectively. Both electrode materials are binder-free prepared by using a catalytic chemical vapour deposition (CVD)approach followed by a facile hydrothermal method for cathode and a one-step environmental-friendly route called hydrothermal carbonization for anode. Using NiO–CoO NSs@CNTs and HTCs, which were directly grown on Ni foam, not only leads to a very small equivalent series resistance, but also provides an impressive capacitive... 

TiO2 nanotube arrays (TNA) have been modified by cobalt phosphate (CoPi) through potentiostatic electrodeposition method. Different samples have been prepared by changing the loaded CoPi through the deposition time from 10 to 960 min. Formed catalytic materials have been characterized by different methods. Although charge transfer resistance of the CoPi/TNA photoanodes have been decreased from 5.5 to 4.0 kΩ by increasing the deposition time from 5 to 60 min, the maximum photoresponse was obtained for 10 min CoPi deposition leading to 24% more photocurrent compare to bare TNA which proposed optimum value for cobalt phosphate decoration. Based on field emission scanning electron microscopy... 

A study has been carried out of the effect of plasma electrolytic oxidation (PEO)on the strength of AA 5052 alloy/polypropylene joints prepared using friction stir spot welding (FSSW). The joint strengths were determined using lap-shear tests and failure modes were investigated using scanning electron microscopy. Comparisons were made between control joints prepared with the alloy in the as-rolled condition or the as-rolled condition with a mechanical key and with PEO-treated alloy, with or without a mechanical key. Mechanical keying alone, provided by infiltration of polymer into holes of either 3 or 4.5 mm diameter drilled in the alloy, yielded enhancements of the joint strength by a... 

A study has been carried out of the effect of an anodizing pre-treatment in a sulphuric acid electrolyte on the strength of AA 5052 alloy/polypropylene joints prepared using friction stir spot welding. Lap-shear tests were used to determine the joint strength. Comparisons were made with joints pre-treated using sand blasting. The failed specimens were examined by scanning and transmission electron microscopy. Anodizing improved the strength of the joints by a factor of about 6 compared with sandblasting. For the anodizing pre-treated joints, melted polymer infiltrated deeply within the nanoporous anodic film, forming a strong polymer-film bond. Joint failure occurred by ductile tearing of...