Sharif Digital Repository

After silica coating of the prepared nickel ferrite nanoparticles, a micrometric layer of zeolitic material (analcime) was grown on the surface. To make the composites good host, surface modification was done with [BMIM]PF6 ionic liquid. Finally, the samples became antibacterial agents via loading the Ag and Au nanoparticles and denoted as X@IL/A/S/NF (X = Ag or Au). All the samples were well characterized by Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and N2 adsorption-desorption isotherms (BET) analysis methods. Antibacterial activity of the prepared samples... 

The aim of this review is to cover advances in noble metal nanoparticle (MNP)-based biosensors and to outline the principles and main functions of MNPs in different classes of biosensors according to the transduction methods employed. The important biorecognition elements are enzymes, antibodies, aptamers, DNA sequences, and whole cells. The main readouts are electrochemical (amperometric and voltametric), optical (surface plasmon resonance, colorimetric, chemiluminescence, photoelectrochemical, etc.) and piezoelectric. MNPs have received attention for applications in biosensing due to their fascinating properties. These properties include a large surface area that enhances biorecognizers... 

Zeolitic imidazole frameworks (ZIFs) provide an exciting platform to design and fabricate non-precious-metal carbon-based catalysts for oxygen reduction/evolution reaction (ORR/OER). Herein, we elaborately design a facile enzyme-assisted synthetic strategy that enables to tailor the ZIFs precursors into structural stable decussation shape, which derived Co nanoislands grafted on decussate N-doped carbon nanoleaves (D-Co@NC) can well retain the interpenetrating nanostructure. Benefiting from the combined advantages of compositions and interpenetrating nanostructures, D-Co@NC possesses 5.2 times higher exposed electrochemical active area than the conventional dodecahedral one, thus endowing... 

Metal Organic Frameworks (MOFs) have received enormous attention in catalysis field due to their special structures and various promising applications. One of the intriguing applications of MOFs is utilization of them as precursors for synthesis of metal oxide nanomaterials. Base on this strategy, in this work, we have applied Cu-MOF to prepare a series of noble metal nanoparticles (Ag and Au) decorated CuO (M/CuO) as efficient catalyst. As-prepared nanocomposites were characterized by various analytical techniques and their catalytic performances appraised by using of the catalytic reduction of p-nitrophenol to p-aminophenol as a reliable model reaction. Experimental results suggest that... 

To improve the efficiency of electrochemical processes for environmental remediation, we present a new type of hybrid nanomaterials based on leaf-like copper-based quaternary transition metals and spongy monolayer graphene. To demonstrate the functionality of the hybrid electrocatalyst, fast and competent electrooxidation of water and glucose is shown. The mechanism of improved catalysis is ascribed to the synergetic catalytic effect of quaternary Cu-Ni-Fe-Co alloy with dendritic morphology along with the highly conductive and spongy structure of the graphene monolayer. It is shown that water oxidation can be performed at a low overpotential of 315 mV to reach a current denisty of 100 mA... 

Precious metal-free electrocatalysts based on two-dimensional nanomaterials have efficiently been used for oxygen evolution reaction; however, the low activity and stability of these materials as compared with noble metals are still distractive. We present a novel and high-performance electrocatalyst based on nanowires of mixed transition metal oxysulfide supported by three-dimensional highly porous graphene networks. Electrochemical studies indicated that the high electron transport medium of nanowires and bilayer graphene nanosheets as well as their high active surface area promote the kinetics of oxygen evolution reaction (OER). A quite small overpotential of 260 mV at the current density... 

Synthesis of efficient, low-cost, and stable bifunctional electrocatalysts with earth-abundant resources for electrochemical water electrolysis is a challenging subject for large-scale energy conversion processes. Herein, we report a high-performance electrocatalyst based on vanadium oxysulfide/cobalt-cobalt sulfonitride (VOS/Co-CoSN) for oxygen and hydrogen evolution reaction (OER and HER). The Co-CoSN film was synthesized on a copper sheet (CS) by a facile electrodeposition method. Then, VOS was electrochemically grown onto the Co-CoSN@CS electrode at various deposition times. At the optimal deposition time (300 s), the obtained VOS-300/Co-CoSN catalyst was studied for OER and HER in... 

In this work, attempt is made to development of active non-precious metal catalysts (NPMCs) for the oxygen reduction reaction in polymer electrolyte fuel cells (PEFCs) based on the heat treatment of poly-aniline/transition metal/carbon precursors. All the materials have been characterized by X-ray diffraction (XRD) small and wide angle, N2 adsorption-desorption isotherms, high-resolution transmission electron microscopy (TEM), Scanning electron microscope (SEM) and X-ray photo-electron spectroscopy (XPS). Moreover for electrochemical evaluation of samples, Rotating Disk electrode (RDE) technique and Fuel Cell test were employed. The results showed that onset potential for the optimized... 

TiO2-graphene (TiO2-GR) nanocomposites were synthesized using photocatalytic reduction method. TiO2-GR nanocomposites were thereafter doped with noble metals (Pt and Pd) by chemical reduction of the corresponding cations. The samples were characterized by different techniques. The addition of GR to TiO2 decreases the crystalline size of TiO2 due to the homogeneous dispersion of the TiO2 nanoparticles on GR sheets and prevention of coagulation of TiO2 nanoparticles during synthesis process. In addition, the surface area of TiO2 was increased by addition of GR and deposition of noble metals which helps to prevent agglomeration of graphene sheets and TiO 2 nanoparticles. Red shifts to the... 

In this study, colloidal tungsten oxide nanoparticles were fabricated by pulsed laser ablation of tungsten target using the first harmonic of a Nd:YAG laser (1064 nm) in deionized water. After ablation, a 0.33 g/lit HAuCl4 aqueous solution was added into as-prepared colloidal nanoparticles. In this process, Au3+ ions were reduced to decorate gold metallic state (Au0) onto colloidal tungsten oxide nanoparticles surface. The morphology and chemical composition of the synthesized nanoparticles were studied by AFM, XRD, TEM and XPS techniques. UV-Vis analysis reveals a distinct absorption peak at ∼530 nm. This peak can be attributed to the surface plasmon resonance (SPR) of Au and confirms... 

Titanium anodes activated by noble metal oxides possess a wide range of advantages and applications. Actually, coating of titanium anodes by highly conductive oxides of noble metals (Ru, Ir) dramatically increases the lifetime of these anodes. In this study, the binary coating consisting of Ti and Ru and the ternary coating consisting of Ti, Ru and Ir were prepared through sol–gel method. After coating of the titanium substrate, the corrosion behavior of coatings was studied by anodic polarization and cyclic voltammetry tests. The lifetime of anodes was determined using accelerated corrosion test. The morphology of coatings was examined by field emission scanning electron microscopy and... 

As microbial fuel cell (MFC) technology continues to gain momentum toward commercialization, the replacement of traditionally used platinum for oxygen reduction with an inexpensive catalyst becomes more important. A nonprecious nitrogen-doped carbon composite catalyst with previous applications in PEM fuel cells is demonstrated for the first time in a single-chamber air cathode MFC with comparisons to a similar platinum-based MFC. The performance of the MFC is compared with a similar MFC using a platinum catalyst and acetate feed. When the platinum is replaced with the catalyst loaded at the surface of the proton exchange membrane (loading density of 1 mg/cm2), MFC operation outperforms a... 

Knowing the metal content of electronic waste is essential to evaluate metal recovery. Lack of a standard method for digestion of precious metals from electronic waste has resulted in difficulty in comparison to the efficiency of recovery. In this study, different precious metal digestion methods and economic value of precious metals from different types of waste printed circuit boards in different fraction sizes, including computer printed circuit boards, mobile phone printed circuit boards, television printed circuit boards, fax machine printed circuit boards, copy machine printed circuit boards, and central processing unit were examined. The optimal digestion method using aqua regia,... 

The development of noble-metal-free electrocatalysts with enhanced active sites is of great significance for the production of renewable energy on large scale. Ultrathin transition metal compounds (e.g., phosphides and sulfides) have unique structural features but their stability and electroactivity must still be improved for practical applications. We propose a new strategy to synthesis ultrathin sheets of Ni-Cu-Co transition metals on porous nickel and self-assemble them into yarn-shaped microspheres. Enhance catalytic activity and stability are then attained by thermochemical phosphorization without morphological modifications. We employed various analytical techniques including XRD, SEM,... 

Hydrogen technology through water electrolyzer systems has attracted a great attention to overcome the energy crisis. So, rationally designed non-noble metal based-electrocatalysts with high activity and durability can lead to high performance water electrolyzer systems and high purity hydrogen generation. Herein, a facile two-step method: hydrothermal and electrodeposition, respectively, are developed to decorate highly porous three-dimensional binder-free structure NiFeO/NiO nanosheets array on Ni foam (NiFeO/NiO/NF) with robust adhesion as a high-performance electrode for Hydrogen Evolution Reaction (HER). The electrodeposition process applied after the initial hydrothermal process... 

Engineering earth-rich, high-efficiency, and nonprecious electrocatalysts is an essential demand for water electrolysis to obtain clean and sustainable fuels. In this research, novel hybrid electrocatalysts based on coupling a hierarchical porous NiCo-mixed metal sulfide with a nanosheet structure (denoted as NiCoS) and a novel three-dimensional (3D) mesoporous open-cage/framelike structure of CoFeS are designed for oxygen evolution reaction (OER). In this regard, the single-step synthesis of a cobalt iron Prussian blue analog (CoFe PBA) frame/cagelike structure was performed without any etching step. Following a comparative study, CoFe PBA precursors were converted and doped with S, Se, and... 

(Lanthanum, Cerium)(Iron, Manganese, Cobalt, Palladium)(Oxygen)3- Perovskite catalyst was prepared by the citrate route and deposited on ceramic monoliths via dip coating procedure. The catalyst was applied on a car with XU7 motors and the amount of emission was monitored with vehicle emission test systems in Sapco company. The results were compared with the imported catalyst with noble metals such as palladium, platinum and rhodium by Iran Khodro company based on the Euro III standards. The catalysts were characterized by specific surface area measurements, scanning electron microscopy, X-ray diffraction, line scan and map. In the results, obtained in the home made sample, the amount of...