Sharif Digital Repository

Acetic acid is one of the most important petrochemical products. Carbonylation of methanol in homogenous phase is one of the major routes for production of acetic acid. Amongst group VIII metal catalysts used in this process iridium has displayed the best capabilities. To investigate effect of operating parameters like: temperature, pressure, methyl iodide, methyl acetate, iridium, ruthenium, and water concentrations on the carbon dioxide formation, experimental design for this system based upon central composite design (CCD) was utilized. Statistical carbon dioxide formation equation developed by this method contained individual, interactions and curvature effects of parameters on the... 

In the present research, we investigate the synergistic effects of Ru-doping and Ar/H2 reduction treatment on the photoelectrochemical water splitting performance and hydrogen evolution rate of TiO2 nanotube array photoelectrodes. The Ti-Ru alloy with 0.2 at. % Ru was used to grow anodic self-organized Ru-doped TiO2 nanotube layers. An ideal synergy between Ar/H2 reduction treatment and Ru-doping results in the extended absorption toward the visible light region and improved photoelectrocatalytic activity. The black Ru-doped TiO2-x photoanode's water splitting rate improves remarkably (∼ninefold) compared to the black TiO2-x sample (∼twofold). Moreover, the black Ru-doped TiO2-x photoanode... 

We have studied the electrical and magnetic properties of normal and superconducting states of RuGd1.6Ce0.4Sr 2Cu2O10-δ (Ru-1222) system, prepared by the standard solid-state reaction technique, with applied magnetic field. The resistivity curves show that at high temperature the system is paramagnetic. At lower temperature, we can observe two magnetic transitions from paramagnetic state to anti-ferromagnetic and from anti-ferromagnetic to ferromagnetic. At room temperature the resistivity of sample shows insulating behavior and superconducting transition occurs at 45 K. Superconducting and magnetic parameters such as superconducting transition temperature Tc, magnetic transition Tirr, have... 

Our previously reported mathematical model for a mixed oxide nanoparticulate-based supercapacitor containing RuO2·xH2O and MO2·yH2O (M being another suitable transition metal) was analyzed. Both double-layer and faradaic processes responsible for charge/discharge were considered. The effects of the intrinsic factors, unit cell length, state of charge, and the exchange current densities of the electrochemical processes of the constituents on the performance of the model supercapacitor were clarified. Compensation effects where each constituent compensates the shortcomings of the other at specific conditions of discharge are analyzed in the light of the model  

Investigation of the X-ray structure of the newly prepared [Ru(NO)(2,6isopPh2Aceq)Cl3] (2,6isopPh2Aceq = bis(2,6-diisopropylphenylimino)acenaphthenequinone) complex revealed for the first time the π-hole interaction involving the coordinated nitrosyl group with DMSO as the solvent of crystallization in the crystal lattice. Processing of CSD data showed only one reported structure. A significant feature of the structure is the presence of n → π∗, π → σ∗, and n → σ∗ interactions due to the coordinated nitrosyl and chloro groups and DMSO. © 2020 The Royal Society of Chemistry  

We have studied the electrical and magnetic properties of RuGd 2-xCexSr2Cu2O10-δ (Ru-1222) with content of Ce = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, prepared by the standard solid-state reaction technique. To determine how the magnetic and superconducting properties of this layered cuprate system can be affected by Ce substitution, the resistivity and magnetoresistivity have been measured at various temperatures. Resistivity curves reveal the presence of four regions for various contents of x. In high temperatures, system is paramagnetic. Magnetic transition from paramagnetic state to antiferromagnetic state occurs at 140 K for x = 0, which varies very slowly with increasing Ce substitution for Gd.... 

Ruthenium oxide was coated on multiwalled carbon nanotubes (MWCNTs) to obtain nanocomposite electrode which has a good response to the pH. To synthesize this electrode, gold and cobalt were coated on a stainless steel 304 substrates, respectively, and then, vertically aligned carbon nanotubes were grown on the prepared substrates by chemical vapor deposition. Gold reduced activity of the stainless steel, while cobalt served as a catalyst for growth of the carbon nanotube. Ruthenium oxide was then coated on MWCNTs via sol-gel method. At last, different techniques were used to characterize the properties of synthesized electrode including scanning electron microscopy (SEM), transmission... 

We have investigated the effect of Ca substitution for Sr site on structural, magnetic and superconducting properties of RuSr2 -x CaxGd1.4Ce0.6Cu2O10 -δ system. In this system, the magnetic coupling of RuO 2 and CuO 2 plays an important role in magnetic and superconducting states. X-ray diffraction analysis shows that all samples are single phase and the lattice parameters decrease continuously by increasing Ca content. The onset superconducting transition temperature is found to decrease with Ca substitution. As Ca content increases, rotation of the RuO 6 octahedron increases and RuO(1)Ru angle decreases. These variations strengthen the magnetic moments in the RuO 2 planes. The enhancement... 

carbonylation of methanol in homogenous phase is one of the major routesfor production of acetic acid. Amongst group VIII metal catalysts used in this process iridium has displayed the best capabilities. To investigate effect of operating parameters like: temperature, pressure, methyl iodide, methyl acetate, iridium, ruthenium, and water concentrations on the reaction rate, experimental design for this system based upon central composite design (CCD) was utilized. Statistical rate equation developed by this method contained individual, interactions and curvature effects of parameters on the reaction rate. The model with p-value less than 0.0001 and R 2 values greater than 0.9; confirmeda... 

In this study, central composite design (CCD) at five levels (-1.63, -1, 0, +1, +1.63) combined with response surface methodology (RSM) have been applied to optimise methanol carbonylation using a ruthenium-promoted iridium catalyst in a homogenous phase. The effect of seven process variables, including temperature, pressure, iridium, ruthenium, methyl iodide, methyl acetate and water concentrations, as well as their binary interactions, were modelled. The determined R 2 values greater than 0.9 for the rate and methane formation data confirmed that the quadratic equation properly fitted the obtained experimental data. The optimum conditions for maximum rate and minimum methane formation were... 

A modified glassy carbon electrode, prepared by potentiostatic electrodeposition of platinum-ruthenium nanoparticles (Pt-RuNPs) onto a multi-walled carbon nanotube (MWCNT) layer, offers dramatic improvements in the stability and sensitivity of voltammetric responses toward methyldopa (m-dopa) compared to glassy carbon electrodes individually coated with MWCNT or Pt-RuNPs. The surface morphology and nature of the hybrid film (Pt-RuNPs/MWCNT) deposited on glassy carbon electrodes was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. A remarkable enhancement in the microscopic area of the electrode together... 

The Flory-Huggins (FH) model has been one of the most used models in theoretical calculations which has been proved to be sensitive to values assigned as interaction parameters. In this work, a predictive equation is implemented to implicitly couple the concept of compressible regular solution theory of Ruzette and Mayes into the original FH model to obtain a new concertation-dependent interaction parameter equation. Then, the modified model (m-FH) is applied for construction of phase diagram of ternary solutions containing polymer/solvent/nonsolvent where experimental data for ternary systems were collected from the literature. In order to compare and analyze the model performance, the... 

Synthesizing efficient electrode materials for water splitting and supercapacitors is essential for developing clean electrochemical energy conversion/storage devices. In the present work, we report the construction of a ruthenium cobalt oxide (RuCo2O4)/Ti3C2Tx MXene hybrid by electrophoretic deposition of Ti3C2Tx MXene on nickel foam (NF) followed by RuCo2O4 nanostructure growth through an electrodeposition process. Owing to the strong interactions between RuCo2O4 and Ti3C2Tx sheets, which are verified by density functional theory (DFT)-based simulations, RuCo2O4/Ti3C2Tx MXene@NF can serve as a bifunctional electrode for both water splitting and supercapacitor applications. This electrode... 

Increasing energy demands for pollution-free and renewable energy technologies have stimulated intense research on the development of inexpensive, highly efficient, and stable non-noble metal electrocatalysts for oxygen evolution reaction (OER). In this study, a superior OER performance was achieved using a tri-metallic (Zn, Co, Ni) high-performance electrocatalyst. We successfully fabricated a peony-flower-like hierarchical ZnCo2O4 through an additive-free hydrothermal reaction followed by heat treatment. Then NiCo-LDH (layered double hydroxides) nano-flakes was electrodeposited on the ZnCo2O4/GCE surface to prepare NiCo-LDH/ZnCo2O4/GCE which was used as electrode for OER. The structure and... 

Exploring bi-functional electrocatalysts with excellent activity, good durability, and cost-effectiveness for electrochemical hydrogen and oxygen evolution reactions (HER and OER) in the same electrolyte is a critical step towards a sustainable hydrogen economy. Three main features such as high density of active sites, improved charge transfer, and optimized electronic configuration have positive effects on the electrocatalyst activity. In this context, understanding structure–composition–property relationships and catalyst activity is very important and highly desirable. Herein, for the first time, we present the design and fabrication of novel MOF-derived ultra-small Ru/RuO2 nanoparticles...