Evaluating electronic structure of quinazolinone and pyrimidinone molecules for its corrosion inhibition effectiveness on target specific mild steel in the acidic medium: A combined DFT and MD simulation study

The quantum chemical calculations, based on density functional theory, have been implemented to explore the corrosion inhibition mechanism and the corresponding inhibition effectiveness of quinazolinone and pyrimidinone compounds, viz., 6-chloroquinazolin-4(3H)-one (Q1A); 2,3-dihydro-3-phenethyl-2-thioxopyrido[2,3-d]pyrimidin-4(1H)-one (Q1B) and 6-chloro-2,3-dihydro-3-phenethyl-2-thioxoquinazolin-4(1H)-one (Q1C) for mild steel in acidic solution. Global reactivity of the molecules related to the quantum chemical parameters such as EHOMO, ELUMO, energy gap (ΔE), softness (S), hardness (η) and fraction of electron transferred (ΔN) between the inhibitor molecule and the metal surface atom have been calculated and explored. In order to describe the reactive sites of the inhibitor molecules Fukui indices analysis has been performed. To mimic the real environment of corrosion inhibition, molecular dynamic (MD) simulations have also been modelled consisting of all concerned species (inhibitor molecule, H2O, H3O+ ion, SO42 − ion and Fe surface) and thereby simulated by the consistent-valence force field (CVFF)

Effect of stereochemical conformation into the corrosion inhibitive behaviour of double azomethine based Schiff bases on mild steel surface in 1 mol L−1 HCl medium: An experimental, density functional theory and molecular dynamics simulation study

Two hitherto unexplored double condensed Schiff bases, namely, 4-(4-((Pyridin-2-yl)methyleneamino)phenoxy)-N-((pyridin-2-yl)methylene)benzenamine (PMB) and 4-(4-(4-((Pyridin-2-yl)methyleneamino)phenoxy)phenoxy)-N-((pyridin-2-yl)methylene)benzenamine (PPMB) were synthesized and their corrosion inhibitive performances on mild steel have been investigated in 1 mol L−1 HCl medium by gravimetric and electrochemical measurements. Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy affirmed the formation of protective films on mild steel surfaces. Contact angle measurement revealed the hydrophobic nature of surface modified by the inhibitor molecules applied in the corrosive solution. The influence of molecular configuration in corrosion inhibition behaviour of inhibitors has been explored by DFT, DFTB calculation and MD simulation

Amine cured double Schiff base epoxy as efficient anticorrosive coating materials for protection of mild steel in 3.5% NaCl medium

A double Schiff base epoxy (DSBE) molecule comprising of 1-phenoxybenzene unit, double azomethine functionalities, two benzene moieties and two terminal epoxy groups (i.e., glycidylether) has been successfully synthesized with an aim of serving as an alternative for the commercially available bisphenol based epoxies. The structure of the synthesized molecule has been affirmed by sophisticated analytical instrumentations such as FT-IR, matrix-assisted laser desorption ionization (MALDI) mass spectrometry and 1H-NMR spectroscopy. Diethylenetriamine (DETA), triethylenetetramine (TETA) i.e., aliphatic and p-phenylenediamine (PPD) i.e., aromatic curing agents have been used to cure DSBE. The amine cured DSBE viz., DSBE + DETA, DSBE + TETA and DSBE + PPD have been further analysed by FT-IR spectroscopy and differential scanning calorimetry. The curing mechanism of epoxy with aliphatic and aromatic amine has also been discussed. The thermal stability of DSBE and amine cured DSBE has been confirmed by thermogravimetry analysis (TGA). The solution of stoichiometric quantity of amines and DSBE in tetrahydrofuran has been applied as coating materials on the surfaces of mild steels. In order to establish the corrosion resistance properties of amine cured DSBE coated substrates, the potentiodynamic polarization technique and electrochemical impedance spectroscopy have been performed in 3.5% NaCl medium which transparently exhibited the superior corrosion inhibition efficacy of DSBE + PPD coated surface showing highest polarization resistance and the lowest rate of corrosion than that of DSBE + DETA and DSBE + TETA. Additionally, the morphological and topographical analysis of the coated substrates have been performed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) to reveal the uniformity as well as soaring smoothness in the surfaces of coating. The hydrophobicity of the developed coating has also been analysed by contact angle measurements

Tailor-made synthesis of an melamine-based aminal hydrophobic polymer for selective adsorption of toxic organic pollutants: an initiative towards wastewater purification

A cost-effective melamine-based polyaminal covalent polymer (CPCMERI-2) has been prepared by a facile synthetic approach using the solvothermal condensation reaction and characterized by solid-state analytical tools like 13C NMR, PXRD, N2 sorption isotherm and FT-IR. The electron-rich moieties in the skeletal backbone induce hydrophobicity in the polymer with an appreciable water contact angle of 130°. AFM study establishes the plausible reason for the hydrophobicity. On account of its high thermal and chemical stability, the polymer CPCMERI-2 has been projected as a next-generation sorbent material for oil-like materials, and executed liquid-phase adsorption of kerosene over water surface. CPCMERI-2 selectively adsorbs kerosene and has a feeble adsorption affinity towards diesel and some other organic solvents like chloroform, benzene, nitrobenzene, and toluene. To improve the bio-compatibility and cost effectiveness of the material, a bio-waste material like the peel of Citrus limetta is used in the composite material, and it unveils a new avenue towards exploring the use of naturally abundant bio-material peels as low-cost sorbent materials. Additionally, CPCMERI-2 has gained attention due to its enormous potential in wastewater purification, which has also been tested in a lab-scale experimental setup. We expect that this material (CPCMERI-2) will harbinger a new type of composite polymer, wherein naturally abundant waste bio-materials could be used as precursors to explore its usefulness as an adsorbent for the removal of oils and organic pollutants

Recent trends in the graphene-based sensors for the detection of hydrogen peroxide

This article intends to cover the latest progress and innovations in the field of graphene-based sensors for the detection of hydrogen peroxide (H2O2). The studies on the electrochemical behavior of a bioactive molecule have become one of the most rapidly developing fields. Biomedical engineering and biotechnology have an enthroned interest in fabricating more precise and accurate voltammetric/amperometric biosensors. One hastily growing area of biosensor design calls for the incorporation of carbon-based nano-materials such as two-dimensional graphene and its derivatives. Herein, a brief overview depicting the voltammetric techniques and how these techniques are useful in biosensing and sensing along with the details of surrounding important concepts such as sensitivity and limits of detection have been discussed in detail. The article discusses the graphene-based research for the effective immobilization of the enzymes such as horseradish peroxidase, hemoglobin, etc. for the accurate detection of H2O2 along with the detailed discussion on various material developed for the fabrication of non-enzymatic H2O2 sensors. The discussion ends with an outlook of future concepts that can be employed in sensor fabrication, as well as restrictions of already proposed materials and how such sensing can be improved. As such, this article can act as a roadmap to direct researchers in the direction of the next generation sensors highlighting the current advancements in the field

Investigation of velocity slip effect on steady state characteristics of finite hydrostatic double-layered porous oil journal bearing

Steady state characteristics of finite hydrostatic double layer porous oil journal bearing are investigated theoretically by incorporating tangential velocity slip at the porous-film interface given by Beavers–Joseph. The governing equations for flow in the porous medium and modified Reynolds equation in the film region are solved simultaneously using finite difference method. The effects of slip and design variables such as feeding parameter, bearing number, eccentricity ratio, slenderness ratio, and anisotropy of permeability have been investigated on bearing performance characteristics like load-carrying capacity, attitude angle, friction variable, and volume flowrate. The results are depicted in the form of graphs that can be utilized during design

Binder-Free Growth of Nickel-Doped Iron Sulfide on Nickel Foam via Electrochemical Deposition for Electrocatalytic Water Splitting

Iron–sulfur-based materials are advantageous for electrocatalytic activity owing to their high natural abundance and lesser toxicity. A few investigations on the hydrogen evolution reaction (HER) catalyzing activity of Fe–S materials were performed. However, the oxygen evolution reaction (OER) catalyzing activity or overall water splitting activity of Fe–S materials has not been studied extensively till date. Another technical aspect that suppresses the activity of the electrocatalyst is related to the usage of polymeric binders for electrode fabrication. Keeping these aspects in mind, iron sulfide was directly electrodeposited on nickel foam by varying the deposition potentials and duration of deposition. Ni-doped O-incorporated iron sulfide having the FeS2 lattice domains was obtained as the deposition product. The morphology, electronic structure, and charge carrier density in the valence band of the electrodeposits changed with the change in duration of electrodeposition, which in turn modulated the electrocatalytic activity. The electrode fabricated at −0.9 V potential after 30 min was found to be superior toward HER and OER. The electrodeposit obtained after 45 min showed comparable HER catalyzing activity. An asymmetric electrolyzer constructed with these electrodes showed a comparable water splitting activity to that of the RuO2(+)||Pt/C(−) electrolyzer and also surpassed its activity at higher potential

Investigation of the surface plasmon polariton and electrochemical properties of covalent and non-covalent functionalized reduced graphene oxide

The surface electronic properties of graphene oxide (GO) were modified through reduction and functionalization. Non-covalent functionalization was found to be superior compared to covalent functionalization due to the formation of few-layer graphene with a low defect content and average crystalline length. Because of the restoration of sp2 hybridization, non-covalently functionalized reduced graphene oxide (rGO) showed a better plasmonic response compared to GO, rGO and covalently functionalized rGO. Due to the available π electrons from the sp2 network of graphene as well as surface functionality, non-covalent functionalized rGO exhibited elevated donor density. Furthermore, due to the synergistic effect of surface electronic properties as well as adsorption and recombination at the barrier, superior charge transfer was achieved at the electrode–electrolyte interface for non-covalent functionalized rGO

A review on the heterostructure nanomaterials for supercapacitor application

The typical physical and chemical properties lead the nanomaterials to breakthrough in the field of energy storage especially, supercapacitor applications. The optimization of electrical conductivity, structural flexibility, band gap and charge carrier mobility are the key point to solve the issues in the electrochemical charge storage mechanism of supercapacitor. The semiconducting heterostructured nanomaterials are the best choice to store energy by near-surface ion adsorption along with additional contribution from fast reversible faradic reactions. The creation of active sites and defects in the grain boundary of the heterostructure materials results in multiple redox activity, superior ionic conductivity and short diffusion path. Therefore, sufficient researches enrooted to the doped and nano heterostructure electrode materials needs to be performed in order to exploit the high power and energy storage applications. This article reviews current trends in the synthesis of heterostructure electrode through hybridization of different electrochemical double layer capacitance (EDLC) and pseudocapacitive materials. This article also emphasize on the effect of doping on the electrode possessing both EDLC as well as the pseudocapacitance. In addition, the advantages of superlattice structure for the superior electrochemical properties are also discussed

Investigation of electrochemical charge storage in nickel-cobalt-selenide/reduced graphene oxide composite electrode and its hybrid supercapacitor device

Nickel-cobalt chalcogenide-based composite materials were prepared by two-step hydrothermal technique. The change in morphology and crystalline phase of the materials with addition of 2D RGO sheet and exchange of anion by selenium was investigated. The alteration in electrochemical properties was also studied and correlated with the change in physicochemical properties. The electrochemical properties of the materials enhanced significantly when selenization occurred in presence of reduced graphene oxide (RGO) sheets. The NiCo2Se4/RGO (NCSG) electrode achieved highest specific capacitance of 1776 F g−1 at 2 A g−1 current density and retained excellent specific capacitance (51%) even at high (50 A g−1) current density. When the NCSG was integrated with sonochemically reduced graphene oxide (SRGO) and formed a hybrid supercapacitor (HSC) (SRGO//NCSG), the device delivered high specific capacitance of 212 F g−1 at 2 A g−1 current density. The HSC achieved a maximum energy density of 66.2 W h Kg−1 at 1500 W kg−1 power density, which is comparable or higher than those of other ternary metal selenide supercapacitors. The HSC exhibited the retention in specific capacitance of ∼93.5% after 5000 GCD cycles, confirmed the good stability and reversibility. These results promoted the NCSG/RGO composite as a new type of promising supercapacitor electrode material