scholarly journals Nanostructured β−NiS Catalyst for Enhanced and Stable Electro−oxidation of Urea

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1280
Author(s):  
Tzu-Ho Wu ◽  
Yan-Cheng Lin ◽  
Bo-Wei Hou ◽  
Wei-Yuan Liang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Hydrothermal Reaction ◽  
Charge Transfer Resistance ◽  
Hydrogen Energy ◽  
Transfer Resistance ◽  
X Ray ◽  
Onset Potential ◽  
Slow Kinetics ◽  
Electro Oxidation

Urea oxidation reaction (UOR) has received a high level of recent interest since electrochemical oxidation of urea can remediate harmful nitrogen compounds in wastewater and accomplish hydrogen fuel production simultaneously. Thus, urea is considered to be potential hydrogen energy source that is inherently safe for fuel cell applications. However, the catalytic reaction suffers from slow kinetics due to six electron transfer in UOR. In this work, β phase NiS is successfully prepared through facile hydrothermal reaction, in which diethanolamine (DEA) was added as chelating agent leading to 3D nanoflower morphology. The crystal structure, surface morphology, and chemical bonding of the β−NiS were characterized by X–ray diffraction (XRD), scanning electron microscope (SEM), and X−ray photoelectron spectroscopy (XPS), respectively. The UOR performance of NiS was evaluated by means of linear sweep voltammetry (LSV), Tafel analysis, electrochemical impedance spectroscopy (EIS), chronoamperometry, and chronopotentiometry in 1 M KOH electrolyte containing 0.33 M urea. Compared to the Ni(OH)2 counterpart, NiS exhibits lower onset potential, increased current responses, faster kinetics of urea oxidation, lower charge transfer resistance, and higher urea diffusion coefficient, leading to the enhanced catalytic performance toward UOR. Moreover, the developed NiS catalyst exhibits superior stability and tolerance towards urea electro−oxidation in 10,000 s test.

scholarly journals From Allergens to Battery Anodes: Nature-Inspired, Pollen Derived Carbon Architectures for Room- and Elevated- Temperature Li-ion Storage

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Jialiang Tang ◽  
Vinodkumar Etacheri ◽  
Vilas G. Pol
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Lithium Ion ◽  
Charge Transfer Resistance ◽  
High Rate ◽  
Energy Storage Devices ◽  
Lithium Storage ◽  
Transfer Resistance ◽  
Carbonaceous Particles ◽  
X Ray

Abstract The conversion of allergic pollen grains into carbon microstructures was carried out through a facile, one-step, solid-state pyrolysis process in an inert atmosphere. The as-prepared carbonaceous particles were further air activated at 300 °C and then evaluated as lithium ion battery anodes at room (25 °C) and elevated (50 °C) temperatures. The distinct morphologies of bee pollens and cattail pollens are resembled on the final architecture of produced carbons. Scanning Electron Microscopy images shows that activated bee pollen carbon (ABP) is comprised of spiky, brain-like and tiny spheres; while activated cattail pollen carbon (ACP) resembles deflated spheres. Structural analysis through X-ray diffraction and Raman spectroscopy confirmed their amorphous nature. X-ray photoelectron spectroscopy analysis of ABP and ACP confirmed that both samples contain high levels of oxygen and small amount of nitrogen contents. At C/10 rate, ACP electrode delivered high specific lithium storage reversible capacities (590 mAh/g at 50 °C and 382 mAh/g at 25 °C) and also exhibited excellent high rate capabilities. Through electrochemical impedance spectroscopy studies, improved performance of ACP is attributed to its lower charge transfer resistance than ABP. Current studies demonstrate that morphologically distinct renewable pollens could produce carbon architectures for anode applications in energy storage devices.

scholarly journals Study of solvent effect on structural and photoconductive behavior of ternary chalcogenides InBiS3-In2S3-Bi2S3 composite thin films deposited via AACVD

2019 ◽  
Vol 42 (1) ◽  
pp. 102-112 ◽  
Author(s):  
Umar Daraz ◽  
Tariq Mahmood Ansari ◽  
Shafique Ahmad Arain ◽  
Muhammad Adil Mansoor ◽  
Muhammad Mazhar
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Visible Region ◽  
Chloroform Solution ◽  
Photocurrent Density ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
X Ray ◽  
Wide Range

Abstract In the present work ternary composite InBiS3-In2S3-Bi2S3 (IBS) thin films are developed using a homogeneous mixture of precursors [Bi(S2CN(C2H5)2)3]2 (1) and [In(S2CNCy2)3]‧2py (2), separately in toluene and chloroform solutions at 500°C under an inert atmosphere of argon gas via aerosol assisted chemical vapor deposition (AACVD) technique. The phase purity, chemical composition and morphological study of both the films deposited from toluene and chloroform solutions are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Field emission scanning electron microscopy (FESEM). The surface morphology showed rod like structure of the films developed from toluene while the films grown from chloroform solution give flake like shapes. The UV-visible spectroscopy explicated that the thin films developed from toluene and chloroform solutions show wide range absorption in whole visible region. Linear Scan voltammetry results show that both the films give negligible dark current, however, the films fabricated from toluene solution give a sharp steep curve with maximum photocurrent density of 2.3 mA‧cm-2 at 0.75 V vs Ag/AgCl/3M KCl using 0.05 M sodium sulphide solution under AM 1.5 G illumination (100 mW‧cm-2), while the film grown from chloroform generates a photocurrent density of 2.1 mA‧cm-2 under similar conditions. The LSV outcomes are further supported by electrochemical impedance spectroscopy (EIS) that gives charge transfer resistance (Rct) value of 8,571 Ω for the films developed from toluene as compared to films fabricated from chloroform with Rct value of 12,476 Ω.

scholarly journals Fabrication, characterization, and photocatalytic performance of ternary cadmium chalcogenides CdIn2S4 and Cd7.23Zn2.77S10-ZnS thin films

2020 ◽  
Vol 44 (1) ◽  
pp. 39-50
Author(s):  
Umar Daraz ◽  
Tariq Mahmood Ansari ◽  
Shafique Ahmad Arain ◽  
Muhammad Adil Mansoor ◽  
Muhammad Mazhar ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Chemical Vapor ◽  
Linear Sweep Voltammetry ◽  
Photocurrent Density ◽  
Charge Transfer Resistance ◽  
Single Step ◽  
Transfer Resistance ◽  
X Ray ◽  
Dual Source

Abstract Dithiocarbamate complexes [Cd(S2CNCy2)2(py)] (1), [In(S2CNCy2)3]·2py (2) and [Zn(S2CNCy2)2(py)] (3) were synthesized and toluene solution of (1) and (2) was used as dual source precursor for the synthesis of CdIn2S4 (CIS), while that of (1) and (3) was applied for the deposition of Cd7.23Zn2.77S10–ZnS composite (CZS-ZS) thin film photoan-odes by employing single step aerosol assisted chemical vapor deposition (AACVD) technique. Deposition experiments were performed at 500°C under an inert ambient of argon gas. The structural properties of deposited films were evaluated by using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The field emission scanning electron microscopy (FESEM) exposed surface morphologies while UV-Visible spectrophotometry revealed that CIS is low band gap photoanode in comparison to CZS-ZS. The comparison of photoelectrochemical (PEC) responses measured in identical conditions in terms of linear sweep voltammetry (LSV) depicts photocurrent density of 4.4 mA /cm2 and 2.9 mA/cm2 at applied potential of 0.7 V under solar light intensity of 100 mW/cm2 for CIS and CZS-ZS respectively. Further, electrochemical impedance spectroscopy (EIS) confirms that PEC properties of CIS are superior to CZS-ZS photoanode as the former offer less charge transfer resistance (Rct) 0.03 MΩ in comparison to CZS-ZS having Rct value of 0.06 MΩ.

Preparation of novel Ti-based MnOx electrodes by spraying method for electrochemical oxidation of Acid Red B

2019 ◽  
Vol 80 (2) ◽  
pp. 365-376
Author(s):  
Xuelu Xu ◽  
Jiao Zhao ◽  
Subei Bai ◽  
Rongrong Mo ◽  
Yan Yang ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Photoelectron Spectroscopy ◽  
Manganese Oxides ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Cell Potential ◽  
Transfer Resistance ◽  
X Ray ◽  
Concentration Changes ◽  
Spraying Method

Abstract At different calcination conditions, titanium-based manganese oxides (MnOx) electrodes were fabricated by spraying method without adhesive. The MnOx/Ti electrodes were applied in electrochemical oxidation of wastewater treatment for the first time. The surface morphologies of electrodes were tested by scanning electron microscopy. The formation of different manganese oxidation states on electrodes was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical properties of the electrodes have been performed by means of cyclic voltammetry and electrochemical impedance spectroscopy. The characterizations revealed that the MnOx/Ti-350(20) electrode, prepared at calcination temperature of 350 °C for 20 min, exhibited fewer cracks on the electrode surface, larger electrochemically effective surface area and lower charge transfer resistance than electrodes prepared at other calcination conditions. Moreover, Acid Red B was used as target pollutant to test the electrode activity via monitoring the concentration changes by UV spectrophotometer. The results showed that the MnOx/Ti-350(20) electrode presented the best performance on decolorization of Acid Red B with the lowest cell potential during the process of electrochemical oxidation, and the chemical oxygen demand (COD) conversion was 50.7%. Furthermore, the changes of Acid Red B during the electrochemical oxidation process were proposed by the UV–vis spectra.

scholarly journals Influence of HAP on the Morpho-Structural Properties and Corrosion Resistance of ZrO2-Based Composites for Biomedical Applications

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 202
Author(s):  
Réka Barabás ◽  
Carmen Ioana Fort ◽  
Graziella Liana Turdean ◽  
Liliana Bizo
Keyword(s):  
Electrochemical Impedance ◽  
Artificial Saliva ◽  
Synergetic Effect ◽  
Composite Layer ◽  
Charge Transfer Resistance ◽  
Processing Route ◽  
Dental Alloys ◽  
Metallic Electrode ◽  
Transfer Resistance ◽  
X Ray

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synergetic effect between the diffusion process through the Chit-composite layer and the roughness of the metallic electrode surface.

scholarly journals Synthesis and Characterization of Electrodeposited C-PANI-Pd-Ni Composite Electrocatalyst for Methanol Oxidation

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
S. S. Mahapatra ◽  
S. Shekhar ◽  
B. K. Thakur ◽  
H. Priyadarshi
Keyword(s):  
Methanol Oxidation ◽  
Electrocatalytic Activity ◽  
Electrochemical Impedance ◽  
Synergistic Effects ◽  
Catalytic Performance ◽  
Charge Transfer Resistance ◽  
Pani Film ◽  
Composite Electrodes ◽  
Transfer Resistance ◽  
Onset Potential

Electropolymerization of aniline at the graphite electrodes was achieved by potentiodynamic method. Electrodeposition of Pd (C-PANI-Pd) and Ni (C-PANI-Ni) and codeposition of Pd-Ni (C-PANI-Pd-Ni) microparticles into the polyaniline (PANI) film coated graphite (C-PANI) were carried out under galvanostatic control. The morphology and composition of the composite electrodes were obtained using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) techniques. The electrochemical behavior and electrocatalytic activity of the electrode were characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometric (CA) methods in acidic medium. The C-PANI-Pd-Ni electrode showed an improved catalytic performance towards methanol oxidation in terms of lower onset potential, higher anodic oxidation current, greater stability, lower activation energy, and lower charge transfer resistance. The enhanced electrocatalytic activity might be due to the greater permeability of C-PANI films for methanol molecules, better dispersion of Pd-Ni microparticles into the polymer matrixes, and the synergistic effects between the dispersed metal particles and their matrixes.

Effect of Zirconium Oxide Reinforcement on Microstructural, Electrochemical and Mechanical Properties of TiNi Alloy Produced Via Powder Metallurgy Route

2021 ◽  
pp. 1-22
Author(s):  
Syed Abbas Raza ◽  
Muhammad Imran Khan ◽  
Muhammad Ramzan Abdul karim ◽  
Rashid Ali ◽  
Muhammad Umair Naseer ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Passive Layer ◽  
Charge Transfer Resistance ◽  
Tini Alloy ◽  
X Ray Diffraction ◽  
Zro2 Content ◽  
Transfer Resistance ◽  
X Ray ◽  
Conventional Sintering ◽  
Layer Resistance

Abstract Equiatomic TiNi alloy composites, reinforced with 0, 5, 10 and 15 vol. % ZrO2, were synthesized using conventional sintering approach. Equiatomic TiNi pre-alloyed powder and ZrO2 powder were mixed in planetary ball mill for 6 hours followed by cold compaction and pressure-less sintering, respectively. The sintered density was found to vary inversely with the addition of ZrO2 content. The X-Ray diffraction spectra have shown the formation of multiple-phases which were resulted from the decomposition of the B19'and B2 phases of the equiatomic TiNi alloy due to the addition of ZrO2 and higher diffusion rate of Ni than that of Ti in the alloy composite. An increase in hardness was noted due to the addition of ZrO2, measured by micro and nanoindentation techniques. Potentiodynamic polarization scan revealed a 10% decrease in the corrosion rate of the composite containing 10 vol. % ZrO2. Electrochemical impedance spectroscopy results indicated an increase in passive layer resistance (Rcoat) due to the increase in charge transfer resistance (Rct) caused by the reduced leaching of ions from the surface.

scholarly journals Croton lechleri Extracts as Green Corrosion Inhibitors of Admiralty Brass in Hydrochloric Acid

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7417
Author(s):  
Carlos Cevallos-Morillo ◽  
Pablo Cisneros-Pérez ◽  
Roxana Llive ◽  
Marvin Ricaurte ◽  
Carlos Reinoso ◽  
...  
Keyword(s):  
Natural Products ◽  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Corrosion Inhibitors ◽  
Electrochemical Impedance ◽  
Transfer Resistance ◽  
X Ray ◽  
Chemical Structures ◽  
Green Corrosion Inhibitors ◽  
Croton Lechleri

Croton lechleri, commonly known as Dragon’s blood, is a tree cultivated in the northwest Amazon rainforest of Ecuador and Peru. This tree produces a deep red latex which is composed of different natural products such as phenolic compounds, alkaloids, and others. The chemical structures of these natural products found in C. lechleri latex are promising corrosion inhibitors of admiralty brass (AB), due to the number of heteroatoms and π structures. In this work, three different extracts of C. lechleri latex were obtained, characterized phytochemically, and employed as novel green corrosion inhibitors of AB. The corrosion inhibition efficiency (IE%) was determined in an aqueous 0.5 M HCl solution by potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy, measuring current density and charge transfer resistance, respectively. In addition, surface characterization of AB was performed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy techniques. Chloroform alkaloid-rich extracts resulted in IE% of 57% at 50 ppm, attributed to the formation of a layer of organic compounds on the AB surface that hindered the dezincification process. The formulation of corrosion inhibitors from C. lechleri latex allows for the valorization of non-edible natural sources and the diversification of the offer of green corrosion inhibitors for the chemical treatment of heat exchangers.

PREPARATION AND INVESTIGATION OF ELECTRODEPOSITED Ni–NANO-Cr2O3 COMPOSITE COATINGS

2016 ◽  
Vol 23 (02) ◽  
pp. 1550111 ◽  
Author(s):  
JIBO JIANG ◽  
CHENQI FENG ◽  
WEI QIAN ◽  
LIBIN YU ◽  
FENGYING YE ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Charge Transfer Resistance ◽  
X Ray Diffraction ◽  
Transfer Resistance ◽  
X Ray ◽  
Potentiodynamic Polarization Curves ◽  
Nucleation Sites ◽  
Passive Transition ◽  
Steel Surfaces

The electrodeposition of Ni–nano-Cr2O3 composite coatings was studied in electrolyte containing different contents of Cr2O3 nanoparticles (Cr2O3 NPs) on mild steel surfaces. Some techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness, the potentiodynamic polarization curves (Tafel) and electrochemical impedance spectroscopy (EIS) were used to compare pure Ni coatings and Ni–nano-Cr2O3 composite coatings. The results show that the incorporation of Cr2O3 NPs resulted in an increase of hardness and corrosion resistance, and the maximum microhardness of Ni-nano-Cr2O3 composite coatings reaches about 495 HV. The coatings exhibit an active-passive transition and relatively large impedance values. Moreover, the effect of Cr2O3 NPs on Ni electrocrystallization is also investigated by cyclic voltammetry (CV) and EIS spectroscopy, which demonstrates that the nature of Ni-based composite coatings changes attributes to Cr2O3 NPs by offering more nucleation sites and less charge transfer resistance.

scholarly journals Electrochemical Hydrogen Evolution over Hydrothermally Synthesized Re-Doped MoS2 Flower-Like Microspheres

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4631 ◽  
Author(s):  
Juan Aliaga ◽  
Pablo Vera ◽  
Juan Araya ◽  
Luis Ballesteros ◽  
Julio Urzúa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Evolution ◽  
Photoelectron Spectroscopy ◽  
Charge Transfer Resistance ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
Transfer Resistance ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

In this research, we report a simple hydrothermal synthesis to prepare rhenium (Re)- doped MoS2 flower-like microspheres and the tuning of their structural, electronic, and electrocatalytic properties by modulating the insertion of Re. The obtained compounds were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Structural, morphological, and chemical analyses confirmed the synthesis of poorly crystalline Re-doped MoS2 flower-like microspheres composed of few stacked layers. They exhibit enhanced hydrogen evolution reaction (HER) performance with low overpotential of 210 mV at current density of 10 mA/cm2, with a small Tafel slope of 78 mV/dec. The enhanced catalytic HER performance can be ascribed to activation of MoS2 basal planes and by reduction in charge transfer resistance during HER upon doping.

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