Sharif Digital Repository

The oxygen evolution reaction (OER) with its sluggish kinetics has imposed a significant barrier to the sustainable and green generation of hydrogen fuel (via electrolysis of water) and the development of metal-air batteries. In this study, we report an efficient and novel OER electrocatalyst based on NiSe2nanoparticles (NPs) and the naturally abundant halloysite clay mineral. The NiSe2/halloysite nanocomposite (NiSe2/H) was prepared by a simple one-step hydrothermal route. The electrocatalytic performance of the as-synthesized nanocomposite and its components (pristine NiSe2and halloysite) toward OER in 1.0 KOH solution was examined. The NiSe2/H nanocomposite exhibited a significantly... 

The development of active, durable, cost-effective, and stable electrocatalysts is an urgent need for various industrial fields including renewable energy systems. The state-of-the-art catalysts suffer from poor water splitting activity in alkaline media due to their sluggish kinetics, high cost, and scarcity on earth to be scaled up. Herein, we present an electrochemical analysis of a nanostructured electrocatalyst based on a face-centered cubic (FCC) copper-rich Cu-Ni-Fe-Cr-Co alloy with a quasi-spherical morphology electrodeposited on a highly porous nickel substrate. Electrochemical studies determine the enhanced electrocatalytic activity toward both hydrogen and oxygen reactions in an... 

A cost-effective, durable, and easy-to-produce improvement in bifunctional electrocatalysts for water splitting is crucial for future renewable energy systems. In this present study, shape-controlled one-dimensional (1D) phosphorized cobalt (CoP) on 3D porous nickel foam (NiF) was synthesized through successive treatment of commercial NiF with acetone and ethanol, followed by hydrothermal growth of Co and final process of phosphorization by thermochemical reactions. The evaluations of products proved reduced overpotential (270 mV at 10 mA. cm−2 for hydrogen evolution reaction (HER) process and a low overpotential of 320 mV to reach a high current density of 20 mA. cm−2), low Tafel slope... 

The development of efficient and cost-effective catalysts for the oxygen evolution reaction is highly desirable for applications that are based on sustainable and clean technologies. In this study, we report the synthesis of a series of cerium(iv) oxide and nickel diselenide nanocomposites (NiSe2/CeO2) as efficient electrocatalysts for the oxygen evolution reaction in an alkaline medium. The ratios of the two substances were optimized to reach the highest catalytic activity. The structure and morphology of synthesized materials were investigated by XRD, FE-SEM, EDX, BET, XPS, and TEM techniques. It was observed that the nanocomposite with a 10 : 1 mass ratio of NiSe2to CeO2showed the best... 

Electrochemical sensing performance of two-dimensional hexagonal boron nitride (2D h-BN) has traditionally been suppressed by their intrinsic electrical insulation and deficient electron transportation mechanism. However, the excellent electrocatalytic activity, high specific surface area, N- and B-active edges, structural defects, adjustable band gap through interaction with other nanomaterials, and chemical functionalization, makes 2D h-BN ideal for many sensing applications. Therefore, finding a pathway to modulate the electronic properties of 2D h-BN while the intrinsic characteristics are well preserved, will evolve a new generation of highly sensitive and selective electrochemical... 

In the present study, a rational two-step strategy is employed for the green, fast, very simple, and highly controllable synthesis of the bimetallic nickel-cobalt-based metal-organic frameworks (MOFs) on glassy carbon substrates by in situ transformation of nickel-cobalt-layered double hydroxide nanosheet (NiCo-LDHs NSs) intermediates into nickel-cobalt-benzene tricarboxylic acid MOFs (E-NiCo-BTC MOFs). The structural characteristics of the electrode materials in each step were investigated via Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, elemental mapping, field emission scanning electron microscopy, and transmittance electron microscopy.... 

Developing effective and priceless electrocatalysts is an indispensable requirement for advancing the efficiency of water splitting to get clean and sustainable fuels. Herein, we reported a feasible strategy for preparing a trimetallic (NiCoFe) superior electrocatalyst with a novel open-cage/3D frame-like structure for an oxygen evolution reaction (OER). It is prepared by consequent thermal treatments of a CoFe Prussian blue analogue frame/cage-like structure under an argon (CoFeA-TT) atmosphere and then electrochemical deposition of nickel-cobalt sulfide nanosheets as a shell layer on it. The electrochemical measurements demonstrated that the deposition of NiCo-S on CoFeA-TT... 

We present enhanced electrocatalytic activity of three-dimensional graphene scaffolds by decoration with one-dimensional CoxNi1-x MOF nanostructures (0 ≤ x ≤ 1). The decreased overpotential and fast kinetics of the oxygen evolution reaction as compared with the existing materials are shown. The developed bimetallic MOF/3DG composites have great potential to be used in electrocatalytic water oxidation. This journal is © The Royal Society of Chemistry  

Insufficient electrocatalytic activity for oxygen reduction/evolution in lanthanum strontium ferrite (LSF) perovskites at temperatures below 700 °C, limits the utilization of these Co-free oxides as oxygen electrodes for intermediate-temperature solid oxide fuel/electrolysis cells (SOFC/SOEC). Marked performance improvement is here reported by decorating the surface with Pr2Ni1-xCuxO4 catalyst particles. Infiltrating porous LSF electrodes with aqueous nitrates solutions containing Pr, Ni and Cu, targeting the compositions Pr2Ni0.7Cu0.3O4 and Pr2Ni0.6Cu0.4O4, significantly reduces the polarization resistance at 650 °C from 0.98 Ω cm2 to 0.16 Ω cm2 and 0.13 Ω cm2 respectively. Electrical... 

Operation of solid oxide fuel/electrolysis cells (SOFC/SOEC) at high temperatures (T > 850 °C) is accompanied by degradation phenomena, which severely affect the operational lifetime of the cell. Degradation processes are expected to occur slower at low temperatures. However, significant reduction in electrocatalytic activity of the oxygen electrode, is one of the major challenges in decreasing the operating temperature down to 500 °C-650 °C. Recently, Pr6O11 infiltrated Ce0.9Gd0.1O2 (CGO) based electrodes have been proposed to realize high electrochemical performance at intermediate temperature. In this study, Pr-oxide has been infiltrated into a well performing sub-micro... 

This work presents a novel melatonin sensor based on unfunctionalized macroporous graphene networks decorated with gold nanoparticles for the differential pulse voltammetric detection of melatonin in pharmaceutical products. Highly porous graphene structures were prepared by metallic template-assisted chemical vapor deposition, and their active surface area and electrocatalytic activity were improved by electrochemical deposition of gold nanoparticles (50-250 nm) on their struts. The graphene-gold electrodes present a highly sensitive performance toward electro-oxidation of melatonin with a wide linear range of 0.05-50 μM, a low detection limit of 0.0082 μM (3σ/m), and a significant... 

Over the last few years, substantial efforts have been made to develop earth-abundant bi-functional catalysts for urea oxidation and energy-saving electrolytic hydrogen production due to their low cost and the potential to replace traditional noble-metal-based catalysts. Nevertheless, finding a straightforward and effective route to prepare efficient catalysts with unique structural features and optimal supports still is a big challenge. Among the various candidates, metal-organic framework (MOF)-derived materials show great advantages as new kinds of active non-precious catalysts. On the other hand, the controllable integration of MOFs and carbon-based nanomaterials leads to further... 

In the present work, N-doped hollow carbon nanospheres (N-HCNSs) is prepared by direct carbonization of polyaniline-co-polypyrrole (PACP) hollow spheres without template needing. Two different NiO nanostructures (nanosheets and nanowires) are prepared by forming a shell around the N-HCNSs via simple hydrothermal/calcination processes (NiO-NSs@N-HCNSs and NiO-NWs@N-HCNSs). The morphology and structure of the nanostructures are characterized using field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The prepared nanocomposites are used as catalysts for the electrocatalytic... 

In this work, we present the design and fabrication of a novel nanocomposite based on noble metal and metal oxide nanoparticles dispersed on highly porous carbon obtained via the pyrolysis of an inorganic complex and metal-organic frameworks. This nanocomposite is prepared by a two-step procedure: first, the composite support of nanoporous carbon (NPC) is obtained by the direct carbonization of the Cr-benzene dicarboxylic ligand (BDC) MOF in an Argon atmosphere at 500 °C (Cr2O3-NPC). A mixture containing Cr2O3-NPC and [PtCl(SnCl3)(SMe2)2] is then prepared, and underflow of Argon is heated to 380 °C. Finally, Pt-SnO2 nanoparticles are loaded on the Cr2O3-NPC support, and the obtained... 

The emergence of nanoscience and nanotechnology has opened up new horizons to researchers. In this regard, carbon nanomaterials are considered as the cornerstone of numerous investigations. Among various carbon nanostructures, “Carbon nanoparticles (CNPs)” have attracted a great deal of attention during the past few years due to their unique properties such as high surface area, non-toxicity, biocompatibility as well as simple and low-cost synthetic procedures via environmentally friendly routes. Thanks to these properties along with their interesting optical behavior, CNPs have found diverse applications in the fields of bioimaging, nanomedicine, photo/electro-catalysis, and bio/chemical... 

The planned design of nanocomposites combined with manageable production processes, which can offer controllability over the nanomaterial structure, promises the practical applications of functional nanomaterials. Hollow core-shell nanostructure architectures represent an emerging category of advanced functional nanomaterials, whose benefits derived from their notable properties may be hampered by complicated construction processes, especially in the sensing domain. In this regard, we designed a highly porous three-dimensional array of hierarchical hetero Cu(OH)2@CoNi-LDH core-shell nanotubes via a quick, very simple, green, and highly controllable three-step in situ method; they were... 

Porous carbon template decorated with mixed transition metals/metal oxides with tunable architecture is becoming increasingly important and attractive as a kind of novel electrode materials. In this way, mixed-metallic metal-organic frameworks (MOFs) provide an opportunity for fabrication of homogeneous mixed metals/metal oxides distribution in the porous carbon frame without any carbon precursor additive. Also, structures, dimensions and electrochemical performance of MOFs can be readily manipulated by simply tuning the metals molar ratio. In this study, we demonstrate the design and fabrication of petal-like NiCo/NiO-CoO metal/metal oxides with a rational composition embedded in 3D... 

Recently, three-dimensional carbon nanostructures have attracted significant attention for biosensing applications. We have prepared highly porous three-dimensional graphene (3DG) structures (90% porosity) by template-assisted chemical vapor deposition technique and enhanced their electrocatalytic activity through in situ electrochemical deposition of rose-like yttrium hexacyanoferrate particles on their struts. The 3DG structure has an average channel size of ∼500 μm, and the microflowers have lateral sizes in the range of 2-10 μm. The performance of the 3DG-based electrode in efficient detection of ascorbic acid was investigated after transferring on a gold screen printed electrode (SPE).... 

Design and fabrication of highly efficient and low-cost oxygen reduction reaction (ORR) electrocatalysts is of paramount importance for practical applications. Herein, we proposed a cost-effective, metal-free catalyst based on ZIF-8 metal-organic framework nanoparticles/electro-polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) film on the surface of flexible carbon cloth (CC) electrode (ZIF-8/PEDOT/CC) via a two-step procedure. For this purpose, worm-like PEDOT nanostructures were deposited on the surface of carbon fibers using a pulse electro-polymerization technique followed by facile growth of ZIF-8 polyhedra nanoparticles via a chemical bath deposition method. The ORR measurements in... 

Design and fabrication of highly efficient and low-cost oxygen reduction reaction (ORR) electrocatalysts is of paramount importance for practical applications. Herein, we proposed a cost-effective, metal-free catalyst based on ZIF-8 metal-organic framework nanoparticles/electro-polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) film on the surface of flexible carbon cloth (CC) electrode (ZIF-8/PEDOT/CC) via a two-step procedure. For this purpose, worm-like PEDOT nanostructures were deposited on the surface of carbon fibers using a pulse electro-polymerization technique followed by facile growth of ZIF-8 polyhedra nanoparticles via a chemical bath deposition method. The ORR measurements in...