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Highly arranged porous anodic titania (TiO2) nanotube arrays (ATNT) were fruitfully fabricated by the anodization of Ti foil in an ammonium fluoride electrolyte.

β-Ni(OH)2 and β-Ni(OH)2/graphene oxide (GO) were prepared on an Ni foil electrode using the electrochemical cyclic voltammetry formed in 0.5 M KOH solution. Several surface analyses such as XPS, XRD, and Raman spectroscopies were used to confirm the chemical structure of the prepared materials. The morphologies were determined using SEM and AFM. The addition of the graphene oxide layer showed a remarkable increase in the specific capacitance of the hybrid. Through the measurements, the specific capacitance values were 280 F g−1 and 110 F g−1 after and before adding 4 layers of GO, respectively. The supercapacitor displays high stability until 500 cycles are charged and discharged almost without a loss in its capacitance values.

Cu2+ doped ZnS nanoparticles (Cu/ZnS) were prepared through a modified chemical precipitation method. The nanoparticles were characterized using UV–vis, PL, XRD, XPS, N2 sorpometry and TEM techniques. The nanoparticles morphology was spherical in shape with a particle size of ∼11.8 nm and ∼13.4 nm for bare and Cu2+ doped ZnS, respectively. Upon doping Cu2+ (0–5 mol %) into ZnS, tuning of band gap from 3.93 to 2.72 eV along with a remarkable enhancement in surface area from 89.5–152.7 m2. g−1 were successfully achieved. Moreover, Cu2+ act as electron trapping centers, which hinder the recombination of the photogenerated electrons and holes as evidenced from the PL intensity behavior. The photocatalytic experiment by degrading 4-chlorophenol (4-CP) under natural solar radiation indicated that the photodegradation efficiency of Cu2+ doped ZnS nanoparticles increased to 91.2 % compared to 22 % for undoped ZnS nanoparticles. Total organic carbon (TOC) analysis was performed to assess the mineralization ability of the Cu2+ doped ZnS nanoparticles which gave 91.5 % TOC removal. For in-depth understanding of the reasons behind Cu2+ doped ZnS nanoparticles photoreactivity, the revealing of reactive oxidative species (ROS) was achieved through scavenging trapping experiments.

In this work, hierarchical TiO2 nanolace (NL-TiO2) films have been synthesized by a two-step anodization technique. This was followed by a reduction in a hydrogen atmosphere to prepare the reduced black version of such hierarchical nanolaces (NL-TiO2-x). The FESEM images confirmed highly-ordered nanolace arrays structure for all the synthesized films. The Ti3+ ions/oxygen vacancies were confirmed using XPS spectra. The photoelectrochemical properties of NL-TiO2-x showed superior character in comparison with NL-TiO2 by the virtue of the promoted electron-hole separation efficiency, which induced by the Ti3+ ions/oxygen vacancies in NL-TiO2-x. The data showed that the NL-TiO2-x film annealed at 650 °C attained the maximum photoelectrochemical properties with a significant ABPE and IPCE of 0.58% and 52.51%, respectively. The applied photocatalytic reduction of Cr (VI) as an environmental contaminant to Cr (III) was effectively done using NL-TiO2-x and NL-TiO2 annealed at 650 °C with a photocatalytic reduction rate 48.15% and 27.5%, respectively.

In this paper, we studied the electrochemical capacitive performance of thermally evaporated copper iodide thin film doped with different quantities of Al (3, 5, 7, and 9 mol%). The morphological structure, crystalline nature, and surface composition of the deposited films with different dopant levels were confirmed using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscopy (FE-SEM). The electrochemical performance was evaluated based on cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS) in a Na

Recently, great attention has been directed towards the fabrication of solar-driven nanophotocatalysts for wastewater treatment. Thus, in this work, CeO2-based nanoheterostructures were synthesized by mixing n-type CeO2 nanoparticles (NPs) with p-type Cu2S and n-type Ag2S NPs to form Cu2S/CeO2 (p–n) and Ag2S/CeO2 (n–n) nanoheterostructures, respectively. The synthesis of pristine CeO2 and CeO2-based nanoheterostructure architectures and their characterization is conducted using XRD, XPS, TEM, HRTEM, UV–Vis, N2 sorpometry, and electrochemical techniques. Pristine CeO2 NPs had a particle size of 3.9 nm and a surface area of 72.40 m2 g−1, which increased with the generation of nanoheterostructures to 12.3 and 11.1 nm and to 81.5 and 101.16 m2 g−1 for Cu2S/CeO2 and Ag2S/CeO2, respectively. Moreover, both nanoheterostructures showed strong levels of visible light absorbance relative to UV absorber pristine CeO2 NPs. Moreover, Mott-Schottky measurements were collected to determine electrochemical flat potential and band gap structures, and based on the derived results, a schematic diagram of the separation of electron–hole and insight into mechanistic routes involved are given. The photocatalytic degradation of rhodamine 6G (R6G) under natural sunlight was investigated. Based on changes in the temporal UV–Vis spectra of R6G observed over time, photocatalytic efficiencies were estimated at 23%, 44% and 30% for pristine CeO2, Cu2S/CeO2 and Ag2S/CeO2, respectively. The enhancement of the photocatalytic performance of the nanoheterostructures was attributed to the generation of p–n and n–n heterojunction arrangements, which facilitated photogenerated charge separation and transfer.

A promising new nanocomposite coating based on poly(butyl methacrylate) (poly(BMA)), graphene oxide (GO) and TiO2 nanoparticles (NPs) (i.e., poly(BMA)/GO/TiO2 blend) is reported for magnesium alloy (AZ31) protection in 3.5% NaCl solution. A significant decrease in the corrosion current and a pronounced increase in the charge transfer resistance were observed using poly(BMA)/GO/TiO2 nanocomposite which acted as an excellent passivation layer for ion diffusion and corrosion. The addition of GOto poly(BMA) retarded the corrosive ions diffusion by forming longer and wrapped pathways. Embedding TiO2 NPs into the poly(BMA)/GO coating, resulted in charge transfer blockage at metal/electrolyte interface which suppressed metal dissolution.

Ideal emitters for organic light-emitting diodes (OLEDs) are capable of efficiently harvesting non-emissive triplet states, have high colour stabilities, and possess high photoluminescence quantum yields (PLQYs). Maintaining colour stability and PLQY is particularly challenging for multi-carbazole thermally activated delayed fluorescence (TADF) materials that form persistent dimers due to intermolecular interactions of their extended aromatic systems (with altered electronic states). Addressing this challenge, three new emitters are presented, which demonstrate that, somewhat counterintuitively, sterically uncrowded acceptor units can suppress these undesirable interactions. They do so by allowing the surrounding carbazole donors to be arranged with lower dihedral angles, which in turn limits their availability for dimerization. A new pyrazine-centered emitter 4CzPyz is contrasted directly with the cyanopyridine and terephthalonitrile analogues, 4CzCNPy and 4CzTPN respectively. The pyrazine derivative demonstrates enhanced colour stability in the solid-state compared to the cyanopyridine and terephthalonitrile acceptors, which we assign to its absence of intermolecular face-to-face aromatic interactions. This suppression of dimer formation is shared by two cyanopyrazine emitters 2Cz2CNPyz and 3CzCNPyz, each of which feature reduced steric pressure and flatter Cz-Pyz dihedral angles than non-heterocyclic analogues. Flatter dihedral angles consequently lead to C–H bonds of the Cz donors extending outwards at angles that prevent the stacking required for dimerization. This expanded understanding of dimer formation in TADF materials will guide future efforts to maintain colour stability in higher performance TADF materials by curbing the prevalence of face-to-face aromatic interactions.

In this study three environmentally friendly ionic liquids (ILs) namely: 1-Methyl-3-propylimidazolium iodide (MPIMI), 1-butyl-3-methylimidazolium iodide (BMIMI) and 1-hexyl-3-methylimidazolium iodide (HMIMI) were examined as inhibitors for suppressing mild-steel corrosion in 1 M HCl solution. PDP, EFM and EIS techniques were used to study the inhibition action on the metal surface. PDP study revealed that these ILs acted as mixed-type inhibitors due to their adsorption on the steel surface following Langmuir adsorption isotherm. The negative values obtained for Gibbs free energy supported the spontaneous physical adsorption of these inhibitors. Pronounced elevation in the inhibition efficiency was achieved with increasing the concentration of the ILs with maximum inhibitions of 93.1%, 87.8% and 80.4% using 5 × 10−3 M for HMIMI, BMIMI and MPIMI, respectively. To confirm the electrochemical results, the surface morphology of mild-steel was examined using AFM, SEM, and FT-IR analysis. The results confirmed the significance of the alkyl-chain length and the iodide anion present in the ILs on the inhibition mechanism. The results obtained from the different electrochemical and imaging techniques supported each other and strongly suggested that these eco-friendly compounds can be important for several industrial applications.

SALDI-MS analysis of pharmaceutical drug molecules (amitriptyline, imipramine and promazine) using carbon-based substrates, namely, activated charcoal (AC), carbon nanotubes (CNTs), carbon black (CB), graphene (rGO), graphene oxide (GO) and graphite, was explored and compared with the conventional organic matrix of MALDI. CB exhibited superior performance with respect to the other substrates in terms of detection sensitivity. Despite the effectiveness of CB to detect all drug molecules, it demonstrated a number of background signals, which may be an issue for the analysis of other molecules in the future. Therefore, for the first time, a CeO2-CB nanocomposite was synthesized and applied as a novel SALDI substrate to minimize the background signals and stabilize CB when exposed to high laser power. The nanocomposite was characterized using XRD, TEM, FTIR, UV–Vis and N2 sorpometry. The spectrum obtained using the novel nanocomposite in the absence of the drug molecules showed minimal background signals compared to CB. Additionally, the CeO2-CB nanocomposite enhanced the detection sensitivity of the drug molecules with a limit of detection (LOD) of 100 ng/mL. This active substrate nanocomposite was further applied for the analysis of drug-spiked beverages without sample pretreatment or extraction, mimicking cases encountered by forensic toxicologists. All of the drugs and/or their adducts were detected in the drug-spiked beverage samples.

Five and ten weight percent-alumina-containing chitosan-AlOx films were prepared via sol–gel processing. The films were AlOx-agglomerate-free. These organic–inorganic films were degraded by heating at 500 °C. The solid powder residues were found by means of thermogravimetry, X-ray diffractometry, infrared spectroscopy, and electron microscopy to consist of alumina (Al2O3) nanoparticles entraping volatile components, whose thermal removal encouraged ambient oxygen uptake. The surface microstructure and morphology of the recovered alumina nanoparticle were inspected by high-resolution transmission and scanning electron microscopy. Also, the surface chemistry and texture were evaluated by X-ray photoelectron spectroscopy and N2 sorptiometry. Coalescences of globular nanoparticles of γ-/η-Al2O3 were the dominant composition of the 800 °C calcination product of the recovered alumina, irrespective of the alumina-content of the film. Upon increasing the calcination temperature up to 1100 °C, an enhanced polymorphic transition into agglomerated nanoparticles of the seldom encountered Iota-(ι-)Al2O3 took place. The high thermal stability of the otherwise unstable transition aluminas (at ≥950 °C) may suggestively owe to its polymorphic interdependence and/or persistent nanoscopic nature (average particle size = ca. 3–4 nm; specific surface area = ca. 80–60 m2/g). The surface chemical composition for the recovered transition aluminas nanopowders promises versatile acid–base properties for catalysis applications. Accordingly, the highly abundant bio-waste, chitosan, was successfully utilized as a novel synthesis medium for catalytic-grade alumina nanoparticles.

Development of a new environmentally safe coating for corrosion protection of metallic surfaces attracted great interest in material science through the past few years. Smart self-healing coatings showed promising corrosion protection of metals and alloys in different technological applications due to releasing the active agents of the coat in a controllable manner for preventing cracks propagation in the protective coat. These coatings possess passive matrix functionality and actively responds to changes in the local environment which make it prompted great interest from material scientists. Smart coatings are made of responsive materials containing unique chemical, physical, mechanical and electrical characteristics. These smart coating are response and interactive with the different environmental changes such as pressure, heat and chemical effects. The smart coatings are generally classified in the basis of preparation techniques, functional and reactive components and their uses and applications. Typical coatings include: self-healing, self-cleaning, microcapsule healing and anticorrosion coatings. In the process of protection of metallic substrates, smart coatings have multi tasks such as sensing, protection and healing. This review aims to highlights the most recent advances about smart coatings with self-healing properties. Preparation of the different smart coatings and its application for different substrates is also reviewed.

In the maritime industry, stainless steel corrosion resistance requires further surface improvement and further enhanced protection using surface coatings. In this study, an engineered copolymer of polyvinylidene fluoride (PVDF) with polymethylmethacrylate (PMMA)-blended coating was found to provide outstanding corrosion resistance for metal surfaces affording protection against severely corrosive marine environments. Electrochemical measurements indicate that corrosion protection of 316 stainless steel was drastically increased when utilizing the KP blend (a combination of PVDF + PMMA), producing a new set of corrosion properties and morphological characteristics. The corrosion protection of the KP coating proved to be very effective in reducing the passive region current density from 2.19 × 10−5 A/cm2 (for bare stainless steel) to 2.63 × 10−10 A/cm2 and the breakdown passive region potential at 0.25 V. This was followed by a significant decrease in corrosion rate, when compared to pure PMMA and PVDF films, during exposure to artificial marine seawater. With the KP film, impedance measurements surpassed those of other films, with a noticeable nonpeak straight line in the phase angle diagram. Optical observation showed that corrosion pits and delamination areas existed under the coatings.

In this investigation, well defined mesoporous zirconia nanoparticles (ZrO2 NPs) with cubic, tetragonal or monoclinic pure phase were synthesized via thermal recovery (in air) from chitosan (CS)- or polyvinyl alcohol (PVA)-ZrOx hybrid films, prepared using sol–gel processing. This facile preparative method was found to lead to an almost quantitative recovery of the ZrOx content of the film in the form of ZrO2 NPs. Impacts of the thermal recovery temperature (450, 800 and 1100 °C) and polymer type (natural bio-waste CS or synthetic PVA) used in fabricating the organic/inorganic hybrid films on bulk and surface characteristics of the recovered NPs were probed by means of X-ray diffractometry and photoelectron spectroscopy, FT-IR and Laser Raman spectroscopy, transmission electron and atomic force microscopy, and N2 sorptiometry. Results obtained showed that the method applied facilates control over the size (6–30 nm) and shape (from loose cubes to agglomerates) of the recovered NPs and, hence, the bulk crystalline phase composition and the surface area (144–52 m2/g) and mesopore size (23–10 nm) and volume (0.31–0.11 cm3/g) of the resulting zirconias.

Novel organic nanoparticles (ONPs) of (E)-2-(4-(hydrazonomethyl)phenoxyl) acetohydrazide (H2) and N′((E)-benzylidene)-2-(4-((E)hydrazonomethyl)phenoxyl)acetohydrazide (H3) were prepared by the re-precipitation method. The ONPs were characterized using MS, 1H-NMR, 13C-NMR, FT-IR, DLS, TEM and XRD. Both nanoparticles revealed a hemispherical shape with a particle size of 3.0 nm and 2.0 nm for H2 and H3 nanoparticles, respectively. The protective effect of the ONPs on mild steel in 1.0 M HCl was monitored by polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The obtained results revealed that the inhibition efficiency increased with an increase in inhibitor concentration. The maximum inhibition efficiencies at a constant concentration of 1 × 10−3 M were 88.2% and 96.7% for H2 and H3, respectively. The inhibition mechanism depended on the physical adsorption of the nanoparticles on the steel surface, which was confirmed by SEM, AFM and impedance results. These novel nanomaterials showed great anti-corrosion behavior and thus can be potentially used in industrial applications such as cooling water systems, pipes, and oil production units.

In this work, the inhibitive effect of some antibacterial drugs against the corrosion of 316 stainless steel in 1M HCl has been studied by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The inhibiting effect explained by adsorption of the additives on steel surface. The inhibition efficiency increases with increasing the inhibitors concentrations and decreases with increasing the temperature. The data obtained fit well to Langmuir adsorption isotherm and the kinetic-thermodynamic model. The results of polarization studies indicate that the investigated antibacterial drugs are mixed type inhibitors. Increasing the inhibition efficiency of the investigated inhibitors with the addition of iodide ions indicates that iodide ions play important role in the adsorption process. The efficiencies obtained from the different electrochemical techniques were in good agreement which prove the validity of these tools in the measurements of the tested inhibitors.

Purpose – The purpose of this paper is to explore the environment around the rail track at different sites in Nile Delta region, Egypt, through the measurements of the air pollutants and corrosive ionic species present in surface soil and also to investigate the impact of the existing contaminants on the composition of iron rust formed on the rail head surface at these sites and then the durability of rail itself. Design/methodology/approach – The soil characterization was studied by means of sieve shakers, pH meter, conductivity meter and ion chromatography instrument. Scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy and X-ray diffraction were used to characterize the rust layer formed on the rail head surface. Findings – The results showed the relation between the contaminants and the composition of the rust layer. Magnetite and goethite were the major phases identified in the rust layers. Akaganeite was detected in the marine atmosphere. Iron sulfide and iron oxide nitrate hydroxide were detected in environments rich in H2S and NO2 gases, respectively. The appearance of phases like FeCl2 and FeOCl only at marine atmospheres reflects that the corrosive species in suspended particulate matter like chloride ion have a higher effect on the rust composition of the rail head surface than that in surface soil layer. Originality/value – This paper revealed the impact of air and soil contaminants on the composition of rust layer on the rail head surface and may provide guidance for the durability of rails and the necessity for their preservation.

In recent years, porous organic polymers (POPs) have received increasing attention and research interest due to their formidable potential applications in gas storage/separation, heterogeneous catalysis, photoelectricity, energy storage and conversion, etc. In this work, we report the design and synthesis of a hydroxyl-functionalized porous organic polymer (PCz-res) by conventional FeCl3-facilitated oxidative polymerization for gas adsorption and energy storage applications. The precursor Cz-res was designed and synthesized by the imidization of anhydride bearing twisted carbazole units with 4,6-diaminoresorcinol. The prepared PCz-res polymer was completely characterized by the usual analytical techniques. PCz-res exhibited a high specific surface area of 1015 m2/g and reversibly adsorbed 20.53 wt% (273 K) and 14.92. wt% (295 K) CO2 at 1 bar with a moderate isosteric heat of CO2 adsorption (22.39 kJ/mol). The favourable properties of PCz-res were attributed to the uniform pore size distribution (0.8 nm), high surface area, rich nitrogen content and presence of polar CO2-philic hydroxyl groups in the polymeric network. These features make the investigated polymer a plausible emerging material in the field of gas adsorption and separation. Moreover, PCz-res was applied in supercapacitor energy storage and exhibited a specific capacitance as high as 434 F g−1 in 1 M H2SO4 at a 2 mV/s scan rate and 367 F g−1 at a current density of 0.5 A g−1. Additionally, PCz-res retained 91% of the initial specific capacitance after 2000 charge/discharge cycles at a current density of 10 A g−1. The structural characteristics of PCz-res lead to a larger accessible surface area and a redox-active structure, resulting in efficient charge energy storage.

SALDI-MS analysis of pharmaceutical drug molecules (amitriptyline, imipramine and promazine) using carbon-based substrates, namely, activated charcoal (AC), carbon nanotubes (CNTs), carbon black (CB), graphene (rGO), graphene oxide (GO) and graphite, was explored and compared with the conventional organic matrix of MALDI. CB exhibited superior performance with respect to the other substrates in terms of detection sensitivity. Despite the effectiveness of CB to detect all drug molecules, it demonstrated a number of background signals, which may be an issue for the analysis of other molecules in the future. Therefore, for the first time, a CeO

Herein, we report a facile method for the fabrication of a hydrothermally modified well shaped nanocubed ZnS quantum dot (NCQD)/polyvinyl alcohol nanocomposite. The prepared nanocomposite via this method was characterized using various techniques such as field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and atomic force microscopy (AFM). For the first time, a thin film of the fabricated nanocomposite was coated on 316L stainless steel alloy by heat treatment. The corrosion protection efficiency of the PVA/ZnS-NCQD nanocomposite coating on stainless steel was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques in 3.5% NaCl solution. The corrosion protection of stainless steel was enhanced in the presence of the PVA/ZnS-NCQD nanocomposite coating which exhibited better corrosion resistance in saline water. The presence of ZnS-NCQDs increases the inhibition efficiency of PVA against the corrosion of stainless steel in chloride solution from 67.0% to 94.0%. The electrochemical corrosion parameters obtained from potentiodynamic polarization and EIS are in good agreement.

The inhibition effect of two quaternary ammonium salts namely: N 1 ,N 2 -didodecyl-N 1 ,N 1 ,N 2 ,N 2 -tetramethylethane-1,2-diaminium bromide (I) and N-(2-hydroxyethyl)-N,N-dimethyldodecan-1-aminium bromide (II) on the corrosion of copper in 1 M HNO 3 has been investigated by polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Polarization studies showed that these compounds are mixed-type inhibitors. The inhibition efficiency increases with increasing the inhibitor concentration and the maximum inhibition (93.9% and 90.8%) was obtained in the presence of 1 × 10 − 3 M of I and II, respectively. The adsorption of these inhibitors on the copper surface obeys Langmuir isotherm. The results obtained from the different electrochemical techniques were in good agreement.

The effect of Egyptian Schinus-terebinthifolius extract (STE) on carbon steel corrosion in 0.5 M HCl solution was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. The results show that STE is a good inhibitor in 0.5 M HCl. The adsorption of STE obeys Langmuir adsorption isotherm. STE acts as mixed-type but mainly cathodic inhibitor in 0.5 M HCl. The thermodynamic parameters of the corrosion process were calculated and discussed. Maximum inhibition approached 93.3% at 900 ppm STE. SEM showed the Protective film formation on steel surface in presence of STE.

The electrochemical behavior of copper-nickel alloy 90Cu-10Ni is studied in various electrolytes of sulfuric acid, sodium sulfate, sodium chloride, and sulfate/chloride-containing electrolytes. The structure and nature of the semi-passivating film formed on the electrode surface depended on the type of electrolyte and exposure time. Relatively high cathodic current densities were measured in sulfuric acid-containing electrolytes with short Tafel regions in the positive side of the steady-state potential. Barrier-thin oxide films mainly composed of Cu+ species are formed at the onset of metal exposure to the electrolytes. Nickel incorporation was observed with relative dissolution into the electrolyte side, with the lowest percentage observed in case of sodium sulfate. Scanning electron microscopy showed compact films formed in sulfuric acid and sodium sulfate, and porous ones in chloride-containing solutions. Film structure was examined by x-ray photo-electron spectroscopy, while both copper and nickel io...

Herein, Begonia obliqua (BGN) plant extract was assessed as a low-cost, green and efficient corrosion inhibitor for low-carbon steel (LCS) in 1 M HCl solution using mass loss, hydrogen evolution, electrochemical impedance spectroscopy, Tafel polarization (TP), electrochemical frequency modulation as well as surface studies by X-ray photoelectron spectroscopy (XPS), scanning electronic microscope and atomic force microscope. Increasing BGN extract dose increases the charge transfer resistance (R ct) and decreases the double-layer capacitance (C dl). The TP results showed mixed-type inhibition behavior of the studied extract with inhibition efficiency (IE) of 87.7% achieved with the addition of 300 ppm of BGN. The adsorption isotherm model of BGN extract on LCS surface followed Temkin adsorption isotherm. The inhibition mechanism of BGN was explained according to the increasing the IE with temperature and the activation parameters which suggest significant chemisorption of the BGN extract on the LCS surface. The XPS studies confirmed the formation of protective layer of BGN extract on LCS surface. Results obtained by different techniques used showed good agreement confirming the possible use of the investigated inhibitor in the industrial application.

In this investigation, well defined mesoporous zirconia nanoparticles (ZrO2 NPs) with cubic, tetragonal or monoclinic pure phase were synthesized via thermal recovery (in air) from chitosan (CS)- or polyvinyl alcohol (PVA)-ZrOx hybrid films, prepared using sol–gel processing. This facile preparative method was found to lead to an almost quantitative recovery of the ZrOx content of the film in the form of ZrO2 NPs. Impacts of the thermal recovery temperature (450, 800 and 1100 °C) and polymer type (natural bio-waste CS or synthetic PVA) used in fabricating the organic/inorganic hybrid films on bulk and surface characteristics of the recovered NPs were probed by means of X-ray diffractometry and photoelectron spectroscopy, FT-IR and Laser Raman spectroscopy, transmission electron and atomic force microscopy, and N2 sorptiometry. Results obtained showed that the method applied facilates control over the size (6–30 nm) and shape (from loose cubes to agglomerates) of the recovered NPs and, hence, the bulk crystalline phase composition and the surface area (144–52 m2/g) and mesopore size (23–10 nm) and volume (0.31–0.11 cm3/g) of the resulting zirconias.

Herein, bare chromia nanoparticles (Cr2O3 NPs) and chromia supported on reduced graphene oxide (rGO) and graphene oxide (GO) hybrids were synthesized, followed by characterization by means of FESEM, Raman spectroscopy, TGA, XRD, TEM/HRTEM, XPS and N2 sorptiometry. The investigated bare Cr2O3 and the hybrids (Cr2O3/rGO and Cr2O3/GO) were employed as catalysts for low-temperature CO oxidation. Compared with the other catalysts, the results revealed efficient catalytic activity using Cr2O3/GO, which was attributed to its higher surface area together with the mixed oxidation state of chromium (Cr3+ and Cr&gt, 3+). These are important oxidation sites that facilitate the electron mobility essential for CO oxidation. Moreover, the presence of carbon vacancy defects and functional groups facilitate the stabilizing of Cr2O3 NPs on its surface, forming a thermally stable hybrid material, which assists the CO oxidation process. The Cr2O3/GO hybrid is a promising low-cost and efficient catalyst for CO oxidation at low temperatures. The higher activity of graphene oxide supported Cr2O3 NPs can provide an efficient and cost-effective solution to a prominent environmental problem.

A conventional type II heterostructure based on CdS/SWCNT/CeO2 was successfully prepared via a modified co-precipitation and hydrothermal method. The as-prepared heterostructure was characterized via UV–Vis, Fluorescence, XRD, XPS and TEM. The morphology of the heterostructure showed spherical nanoparticles with a particle size of 5.1 nm for CdS/CeO2 on the SWCNT. These properties were translated into remarkable enhancement in the photodegradation of Rhodamine 6G (R6G) dye as a model pollutant for textile and food stuff industries under natural solar radiation. The photo-experiments showed an enhanced photocatalytic activity of CdS/CeO2 and CdS/SWCNT/CeO2 to be 79.3% and 86.4% respectively which are two-fold much greater than that of bare CeO2 NPs (36.6%). Also, the calculated photonic efficiencies (ζ) were found to be 11.7%, 39% and 54.5% for CeO2, CdS/CeO2 and CdS/SWCNT/CeO2 nanostructures respectively. Total organic carbon (TOC) was used to further estimate the mineralization capability of the heterostructure (94% TOC Removal). Furthermore, the band alignment of CdS/SWCNT/CeO2 heterostructure was determined via Mot-Schottky plots and Valence and Core-Level X-ray Photoelectron Spectroscopy, which provided a deep insight about the photodegradation efficiency. For in-depth understanding what happens during the photodegradation, the detection of reactive oxidative species (ROS) was investigated by the trapping experiments.

The inhibition effect of cinnamon plant extract as a green corrosion inhibitor for steel in sulfide polluted salt water was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and electrochemical fre- quency modulation (EFM). The results showed that cinnamon plant extract in sulfide polluted salt water is a good corrosion inhibitor with inhibition efficiency reached to 80% at 250 ppm of the plant extract. The adsorption of cinnamon obeys Temkin adsorption isotherm, and acts as a mixed-type of inhibitor but dominantly as a cathodic inhibitor in sulfide polluted salt water.

Oxide films were grown over 90Cu-10Ni alloy using electrochemical polarization. The structure of the films was determined using a variety of surface techniques. Polarization curves were recorded for the alloy in different electrolytes of chloride, sulfate and the corresponding mixtures. It was ascertained that a protective layer consisting mainly of a thin, strongly adherent inner barrier Cu2O-layer that is followed by a porous and thick outer Cu(II) hydroxide/oxide-layer is formed. Nickel affects the barrier properties of the surface film through a segregation of Ni from the alloy into the Cu2O layer. The composition of the film formed over 90Cu-10Ni alloy was determined at different polarization times using FE-SEM/EDAX, XPS, ICP-ES, and electrochemical measurements. The ratio of Cu:Ni is maintained in the film composition after few seconds from the inset of polarization in chloride containing electrolytes. Ni-content in the film decreases and then increases after 30 and 60 minutes of the inset of polarization, respectively. In sodium sulfate and sulfuric acid solutions, the Cu:Ni ratio in the film is respected throughout the polarization times.

The electrochemical behavior and corrosion inhibition of zinc in 0.5 M H2SO4 in the absence and presence of some chromones has been investigated using weight loss, potentiodynamic polarization, electrochemical impedance spectros- copy (EIS) and electrochemical frequency modulation (EFM) techniques. The presence of these investigated compounds in the corrosive solutions decrease the weight loss, the corrosion current density, and double layer capacitance but increases the charge transfer resistance. Polarization studies were carried out at room temperature, and showed that all the studied com- pounds act as mixed type inhibitors with a slight predominance of cathodic character. The effect of temperature on corrosion inhibition has been studied and the thermodynamic activation and adsorption parameters were determined and discussed. The adsorption of the investigated compounds on zinc was found to obey Langmuir adsorption isotherm.

The inhibiting effect of Roselle extract (Krd) on carbon steel in 0.5 M HCl solution was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) methods. It was found that Krd extract acts as a good inhibitor for carbon steel corrosion in the acid solution. The results showed that Krd extract simultaneously retarded the hydrogen evolution on the cathode and the metal dissolution on the anode, which indicated that this inhibitor is an excellent mixed-type (cathodic/anodic) inhibitor. The dissolution rate decreases with increasing Krd extract concentration and increases with increasing the temperature. The adsorption of Krd extract on the active cathodic sites was found to follow the Langmuir adsorption isotherm. The maximum inhibition approached 91.0 % in the presence of 500 ppm Krd using the EFM technique. The formation of a protective film on the carbon steel surface in the presence of Krd was shown and confirmed by SEM results. There are good agreements between EIS, EFM, the potentiodynamic polarization data, and SEM/EDX results.

This work investigates the inhibition effect of 5-methyl 1-H benzotriazole (MBT) on the dissolution behavior of α-aluminum bronze in clean and sulfide-polluted salt water using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM) and scanning electron microscopy (SEM) techniques. The inhibition efficiency increases with the increasing MBT concentration and decreases with the increasing temperature. The adsorption process of MBT is spontaneous and follows Langmuir adsorption isotherm model. MBT possesses excellent inhibiting effect for the corrosion of α-Al-bronze, which acts as a mixed type inhibitor. Thermodynamic and kinetic parameters for the adsorption process were determined. The presence of sulfide ions (2 ppm) decreases the inhibition efficiency of MBT against the corrosion of Al-bronze alloy in chloride solutions from 94.7% to 89% as also confirmed via SEM images. The results obtained from the different techniques were in good agreement, which prove the validity of these tools in the measurements of the tested inhibitor.

The inhibiting effect of seven ionic liquids (ILs) with various anions, cations, and alkyl chain lengths on mild steel corrosion in acidic solution (1 M HCl) was demonstrated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). ILs with different chain lengths such as 1-ethyl-3-methyl-imidazolium hexafluorophosphate (EMIMPF6), 1-methyl-3-pentyl-imidazolium hexafluorophosphate (PenMIMPF6), and 1-methyl-3-octyl-imidazolium hexafluorophosphate (OctMIMPF6) were examined. In addition, ILs with various anions such as 1-methyl-1-octyl-pyrrolidinium hexafluorophosphate (OctMpyrPF6), 1-methyl-1-octyl-pyrrolidinium thiocyanate (OctMpyrSCN), and 1-methyl-1-octyl-pyrrolidinium dicyanamide (OctMpyrN(CN)2) were considered. Furthermore, ILs with various cations such as 1-octylpyridinium hexafluorophosphate (OctpyPF6), OctMpyrPF6, and OctMIMPF6 were compared. Of all the ILs successfully synthesized in our laboratory, three of them were new: OctMpyrPF6, OctMpyrSCN, and OctMpyrN(CN)2. PDP experiments indicated that the investigated ILs were inhibitors of the mixed type. The adsorption of the studied ILs at the interface of the mild steel/electrolyte obeyed the Langmuir adsorption isotherm, which was also confirmed by SEM and attenuated total reflectance (ATR)-FTIR. The adsorption free energy (ΔG°ads) of these ILs showed negative values, which confirms their spontaneous physical adsorption. In comparing ILs with the same anion and cation, the IL OctMIMPF6, which had the longest alkyl chain, gave the best protection efficiency. The N(CN)2 anion showed better protection for mild steel than SCN and PF6. Imidazolium cation gave better inhibition than pyrrolidinium and pyridinium cations. SEM and ATR-FTIR analyses confirmed the strong adsorption of the studied ILs on the metal surface to form a protective film, which supports the electrochemical and the theoretical results.

Extract of ginger has been evaluated as a green inhibitor for the corrosion of steel in sulfide polluted NaCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Potentiodynamic polarization measurements showed that this extract acts as a mixed type inhibitor but mainly inhibits the cathodic reaction. The inhibition efficiency was found to increase with inhibitor concentra- tion reaching to approximately 83.9% using 250 ppm of ginger. Nyquist plots show a single capacitive loop in uninhibited and inhibited solutions. From EFM the causality factors are very close to theoretical values which indicate that the measured data are of good quality. The adsorption process of the studied extract on steel surface obeys Temkin adsorption isotherm. The results obtained from the different electrochemical techniques were in good agreement which prove the validity of these tools in measurement of corrosion rate. Ginger extract has no effect on Escherichia Coli and can be applied safely on waste water treatment plants.

The inhibition effect of cefoperazone (CP) on the corrosion behavior of carbon steel in 0.5 M HCl solution was studied using potentiodynamic polarization, electrochemical impedance spectroscopy, and electrochemical frequency modulation techniques along with scanning electron microscopy (SEM). Results showed that the inhibition efficiency increases with increasing inhibitor concentration and decreases with increasing the temperature. The results indicated that the inhibitive action of CP can be attributed to its adsorption. The results show that CP possesses excellent inhibiting effect for the corrosion of carbon steel and the inhibitor acts as mixed-type inhibitor. The adsorption process is spontaneous and follows Langmuir adsorption isotherm model. The surface adsorption of the inhibitor molecules decreases the double-layer capacitance and increases the polarization resistance. SEM results indicate the formation of an adsorbed protective film on the metal surface. The results obtained from the different techniques were in good agreement which prove the validity of these tools in the measurements of the tested inhibitor.

The stress corrosion cracking (SCC) behavior of α-aluminum bronze (Cu7Al) has been investigated in nitrite solution under open circuit and at different anodic potentials and compared to α-brass using the constant slow strain rate technique. The electrochemical behavior was also studied using Tafel and electrochemical frequency modulation (EFM) techniques. While α-brass was quite susceptible to SCC in relatively concentrated sodium nitrate (NaNO2) and highly anodic potentials, α-Al bronze was found to be resistant to SCC. The resistance of α-Al bronze to SCC was attributed to the presence of aluminum oxide (Al2O3) on its surface. Although the time to failure and stress ratio remained virtually constant for α-Al bronze, they decreased sharply with increasing the anodic potential in the case of α-brass. The mode of failure was predominantly ductile for α-Al bronze under various conditions. Previous findings for the change of the mode of failure from intergranular at open-circuit potential to transgranular cr...

Electrochemical techniques were used to investigate the effect of cysteine (cys) on the dissolution behavior of Cu10Ni alloy in sulfide-polluted salt water through the analysis of the alloy electrochemical behavior including Tafel polarization and electrochemical frequency modulation (EFM) along with scanning electron microscopy (SEM) and energy dispersive X-ray diffraction (EDX). The results showed that cys acts as a mixed type inhibitor. The dissolution rate decreases with increasing cys concentration and increases with increasing the temperature. An adherent layer of inhibitor molecules on the alloy surface is proposed to account for their inhibitive action. The adsorption of cys on the active cathodic sites was found to follow the Langmuir adsorption isotherm from which the thermodynamic parameters of adsorption and corrosion processes were determined and discussed. A synergistic effect was observed between cys and potassium iodide (KI). EFM data are in good agreement with SEM and EDX results.

The effect of cefazolin (CZ) and cefotaxime (CT) as corrosion inhibitors for carbon steel in 0.5 M H2SO4 solution was investigated by use of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), and scanning electron microscopy (SEM). CZ and CT acted as mixed-type inhibitors. Inhibition increased with increasing inhibitor concentration and decreased with increasing temperature. Adsorption of the inhibitors obeyed the Langmuir adsorption isotherm. SEM confirmed inhibition by the inhibitors. Inhibition by 5 × 10−4 M CZ and 7 × 10−4 M CT approached 99.6 % and 90.9 %, respectively. The EIS and EFM results were in good agreement with the potentiodynamic data.

Corrosion is a natural and inevitable problem that is still a challenge in materials design, with regard to achieving greater operational efficiency. In this study, the electrochemical and stress corrosion cracking (SCC) behavior of Cu10Ni alloy in a 3.5% NaCl solution in the presence of different concentrations of sulfide ions were studied. The presence of sulfide ions has been shown to increase the susceptibility of the material to SCC at different strain rates. The addition of glycine (gly) to the test electrolyte increased the time to failure by changing the mode of failure from brittle transgranular cracking to ductile failure. Therefore, gly can be considered as a potential environmentally friendly corrosion inhibitor. The electrochemical measurements showed that gly acts as a mixed corrosion inhibitor. The synergistic effect of potassium iodide (KI) and gly is also investigated. Electrochemical frequency modulation (EFM) and potentiodynamic polarization data are in good agreement with the SCC results.