Browsing by Author "Boukherroub R."

Now showing 1 - 4 of 4

Cathodic activation of titanium-supported gold nanoparticles: An efficient and stable electrocatalyst for the hydrogen evolution reaction
(2016-04-27) Amin M.A.; Fadlallah S.A.; Alosaimi G.S.; Kandemirli F.; Saracoglu M.; Szunerits S.; Boukherroub R.
As-polished titanium (Ti) substrates decorated with dispersed gold nanoparticles (Au NPs/Ti) of various sizes and densities were prepared here to effectively catalyze hydrogen evolution reaction (HER) in 0.5 M H2SO4. These materials were synthesized adopting a facile one-step wet chemical method without using reducing agents, stabilizers, or any chemical pre-treatment, where Ti acts as both the reducing agent and support. This was achieved via soaking the Ti substrates for 30 min in a gold precursor bath as a function of temperature (5-65°C). Morphological characterizations of the synthesized Au NPs/Ti catalysts indicated a size decrease and density increase of loaded Au NPs with the rise of temperature. Cathodic polarization measurements revealed that the catalyst loaded with the highest density of Au NPs exhibited the best HER activity with onset potential (EHER), exchange current density (jo), and Tafel slope (βc) of -44 mV (RHE), 6.0 × 10-3 mA cm-2, and 40 mV decade-1, respectively. This activity has markedly increased upon cathodic activation (cathodic pre-polarization treatment at -2 V (SCE) for 12 h) that yielded a Ti substrate with a porous-like network structure decorated with highly dispersed Au NPs. In addition, a catalytically active TiH2 phase was formed (as evidenced from XRD and XPS) on such a porous substrate. Such cathodically pre-treated catalyst recorded HER electrochemical parameters of -18 mV (RHE), 0.117 mA cm-2, and 38 mV decade-1, thus approaching the commercial Pt/C catalyst (EHER: 0.0 mV, jo: 0.78 mA cm-2, and βc: 31 mV dec-1). The stability of the best catalyst was assessed employing cyclic polarization and chronoamperometry measurements. It exhibited a good stability with improved activity during stability testing.
Electrochemical, theoretical and surface physicochemical studies of the alkaline copper corrosion inhibition by newly synthesized molecular complexes of benzenediamine and tetraamine with π acceptor
(2020-12-15) Ibrahim M.M.; Mersal G.A.M.; Fallatah A.M.; Saracoglu M.; Kandemirli F.; Alharthi S.; Szunerits S.; Boukherroub R.; Ryl J.; Amin M.A.
Two charge transfer complexes, namely [(BDAH)+(PA−)] CT1 [(BTAH)2+(PA−)2] and CT2 (BDAH = 1,2-benzenediamine, BTAH = 1,2,4,5-benzenetetramine, and PA− = 2,4,6-trinitrophenolate), were synthesized and fully characterized using various spectroscopic techniques. CT1 and CT2 were tested as inhibitors to effectively control the uniform and anodic corrosion processes of copper in an alkaline electrolyte (1.0 M KOH) using various electrochemical techniques. As a reference point, results were compared with the potassium salt of the π-acceptor potassium 2,4,6-trinitrophenolate (designated here as PA−K+). The highest inhibition efficiency (97%) was recorded for inhibitor CT2 at a concentration of 1.0 mM. The inhibition mechanism was discussed based on scanning electron microscopy and X-ray photoelectron spectroscopy results of the corroded and inhibited Cu surfaces. A theoretical study, based on quantum-chemical calculations of the synthesized compounds, performed by the DFT/B3LYP method with a 6-311++G(2d,2p) basis set by using Gaussian 09, Revision A.02 program, was also included to support experimental findings. The various quantum chemical parameters such as EHOMO, ELUMO, chemical hardness, and chemical softness of the investigated molecules were calculated, and their correlation with the inhibition efficiency of the synthesized compounds was discussed.
Synthesis and characterization of new 1,3,4-thiadiazole derivatives: study of their antibacterial activity and CT-DNA binding
(2022-10-17) Sayiner H.S.; Yilmazer M.I.; Abdelsalam A.T.; Ganim M.A.; Baloglu C.; Altunoglu Y.C.; Gür M.; Saracoglu M.; Attia M.S.; Mahmoud S.A.; Mohamed E.H.; Boukherroub R.; Al-Shaalan N.H.; Alharthi S.; Kandemirli F.; Amin M.A.
1,3,4-Thiadiazole molecules (1-4) were synthesized by the reaction of phenylthiosemicarbazide and methoxy cinnamic acid molecules in the presence of phosphorus oxychloride, and characterized with UV, FT-IR, 13C-NMR, and 1H-NMR methods. DFT calculations (b3lyp/6-311++G(d,p)) were performed to investigate the structures' geometry and physiochemical properties. Their antibacterial activity was screened for various bacteria strains such as Enterobacter aerogenes, Escherichia coli ATCC 13048, Salmonella kentucky, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus and Gram positive such as Staphylococcus aureus ATCC 25923, Listeria monocytogenes ATCC 7644, Enterococcus faecium, Enterococcus durans, Staphylococcus aureus ATCC, Serratia marcescens, Staphylococcus hominis, Staphylococcus epidermidis, alfa Streptococcus haemolyticus, Enterococcus faecium and found to have an inhibitory effect on Klebsiella pneumoniae and Staphylococcus hominis, while molecules 1, 3 and 4 had an inhibitory effect on Staphylococcus epidermidis and alpha Streptococcus haemolyticus. The experimental results were supported by the docking study using the Kinase ThiM from Klebsiella pneumoniae. All the investigated compounds showed an inhibitory effect for the Staphylococcus epidermidis protein. In addition, the mechanism of the 1-4 molecule interaction with calf thymus-DNA (CT-DNA) was investigated by UV-vis spectroscopic methods.
Synthesis of Cyano-Benzylidene Xanthene Synthons Using a Diprotic Brønsted Acid Catalyst, and Their Application as Efficient Inhibitors of Aluminum Corrosion in Alkaline Solutions
(2022-09-01) Amin M.A.; Mersal G.A.M.; El-Hendawy M.M.; Shaltout A.A.; Badawi A.; Boman J.; Gobouri A.A.; Saracoglu M.; Kandemirli F.; Boukherroub R.; Ryl J.; Khalifa M.E.
Novel cyano-benzylidene xanthene derivatives were synthesized using one-pot and condensation reactions. A diprotic Brønsted acid (i.e., oxalic acid) was used as an effective catalyst for the promotion of the synthesis process of the new starting xanthene–aldehyde compound. Different xanthene concentrations (ca. 0.1–2.0 mM) were applied as corrosion inhibitors to control the alkaline uniform corrosion of aluminum. Measurements were conducted in 1.0 M NaOH solution using Tafel extrapolation and linear polarization resistance (LPR) methods. The investigated xanthenes acted as mixed-type inhibitors that primarily affect the anodic process. Their inhibition efficiency values were enhanced with inhibitor concentration, and varied according to their chemical structures. At a concentration of 2.0 mM, the best-performing studied xanthene derivative recorded maximum inhibition efficiency values of 98.9% (calculated via the Tafel extrapolation method) and 98.4% (estimated via the LPR method). Scanning electron microscopy (SEM) was used to examine the morphology of the corroded and inhibited aluminum surfaces, revealing strong inhibitory action of each studied compound. High-resolution X-ray photoelectron spectroscopy (XPS) profiles validated the inhibitor compounds’ adsorption on the Al surface. Density functional theory (DFT) and Monte Carlo simulations were applied to investigate the distinction of the anticorrosive behavior among the studied xanthenes toward the Al (111) surface. The non-planarity of xanthenes and the presence of the nitrile group were the key players in the adsorption process. A match between the experimental and theoretical findings was evidenced.