Bimetallic Nanocomposites of Palladium (100) and Ruthenium for Electrooxidation of Ammonia

2016 ◽  
Vol 44 ◽  
pp. 100-113
Author(s):  
Nolubabalo Matinise ◽  
Noluthando Mayedwa ◽  
Chinwe O. Ikpo ◽  
Ntuthuko Wonderboy Hlongwa ◽  
Miranda M. Ndipingwi ◽  
...  
Keyword(s):  
Ammonia Oxidation ◽  
Active Surface ◽  
Charge Transfer Resistance ◽  
Active Surface Area ◽  
Peak Current Density ◽  
Transfer Resistance ◽  
Bimetallic Nanocomposites ◽  
A Charge ◽  
Electron Transfer Processes ◽  
Conductive Properties

Symmmetrically oriented Pd (100) and its bimetallic Pd (100)Ru electrocatalysts were chemically synthesized and their conductive properties employed in the electrochemical oxidation of ammonia. Electrochemical data based on EIS, SWV and CV revealed that the Pt/Pd (100)Ru electrode showed a better conductivity and higher catalytic response towards the electrooxidation of ammonia compared to Pt/Pd (100) electrode. This was demonstrated by the EIS results where Pt/Pd (100)Ru gave a charge transfer resistance (Rct) of 48.64 Ω, high exchange current and lower time constant (5.2738 x 10-1A and 3.2802 x 10-7 s /rad) values while the Pt/Pd (100) had values of 173.2 Ω, 1.4811 x 10-1A and 4.8321 10-7 s /rad. The drastic drop in Rct highlights the superiority of the Pt/Pd (100)Ru over the Pt/Pd (100) and confirms that facile interfacial electron transfer processes occur on the Pt/Pd (100)Ru electrode during the electrocatalytic ammonia oxidation. Investigations through voltammetry revealed that the Pt/Pd (100)Ru had a higher peak current density and a shift in potential to more negative values at ≈ -0.2 V and ≈ -0.4 V. The EASA value of Pt/Pd (100)Ru was found to be 119.24 cm2 whereas Pt/Pd (100) had value of 75.07 cm2. The high electrochemically active surface area of Pd (100)Ru at 119.24 cm2 compared to the 75.07 cm2 for Pd (100) strengthened this observation in performance between the two catalysts for ammonia electrooxidation.

Ultrathin nickel boride nanosheets anchored on functionalized carbon nanotubes as bifunctional electrocatalysts for overall water splitting

2019 ◽  
Vol 7 (2) ◽  
pp. 764-774 ◽  
Author(s):  
Xuncai Chen ◽  
Zixun Yu ◽  
Li Wei ◽  
Zheng Zhou ◽  
Shengli Zhai ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Charge Transfer ◽  
Active Surface ◽  
Charge Transfer Resistance ◽  
Active Surface Area ◽  
Transfer Resistance ◽  
Functionalized Carbon Nanotubes ◽  
Electrochemically Active ◽  
Metal Borides ◽  
Electrochemically Active Surface

Carbon nanotubes increase electrochemically active surface area and reduce charge transfer resistance of transition metal borides.

scholarly journals A Low Cost Fe3O4–Activated Biochar Electrode Sensor by Resource Utilization of Excess Sludge for Detecting Tetrabromobisphenol A

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 115
Author(s):  
Suxing Luo ◽  
Meizhi Yang ◽  
Yuanhui Wu ◽  
Jiang Li ◽  
Jun Qin ◽  
...  
Keyword(s):  
Electrochemical Sensors ◽  
Low Cost ◽  
Active Surface ◽  
Charge Transfer Resistance ◽  
Tetrabromobisphenol A ◽  
Active Surface Area ◽  
Excess Sludge ◽  
Transfer Resistance ◽  
Activated Biochar ◽  
Bet Analysis

Owing to its ubiquity in natural water systems and the high toxicity of its accumulation in the human body, it is essential to develop simple and low-cost electrochemical sensors for the determination of 3,3′,5,5′-tetrabromobisphenol A (TBBPA). In this work, Fe3O4–activated biochar, which is based on excess sludge, was prepared and characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and BET analysis to analyze its basic features. Subsequently, it was used to fabricate an electrochemical sensor for the detection of TBBPA. The electrochemical test results revealed that the Fe3O4–activated biochar film exhibited a larger active surface area, a lower charge transfer resistance and a higher accumulation efficiency toward TBBPA. Consequently, the peak current of TBBPA was significantly enhanced on the surface of the Fe3O4–activated biochar. The TBBPA sensing platform developed using the Fe3O4–activated biochar composite film, with relatively a lower detection limit (3.2 nM) and a wider linear range (5–1000 nM), was successfully utilized to determine TBBPA levels in water samples. In summary, the effective application of Fe3O4–activated biochar provided eco-friendly and sustainable materials for the development of a desirable high-sensitivity sensor for TBBPA detection.

Effect of Plating Solutions on Supercapacitor Characteristics of MnO2 Films

2010 ◽  
Vol 113-116 ◽  
pp. 1810-1813
Author(s):  
Fang Xiao ◽  
You Long Xu
Keyword(s):  
Electrode Materials ◽  
Electrochemical Impedance ◽  
Equivalent Circuit Model ◽  
Active Surface ◽  
Charge Transfer Resistance ◽  
Electrochemical Impedance Spectrum ◽  
Active Surface Area ◽  
Cyclic Voltammograms ◽  
Supercapacitor Electrode ◽  
Transfer Resistance

MnO2 films were electrodeposited on the Ti substrates by galvanostatic method in various plating solutions, which was MnCl2, Mn(NO3)2, MnSO4 and Mn(CH3COO)2 solutions, respectively. On X-ray diffraction test, Crystal structures of all MnO2 films were associated to α-MnO2 of tetragonal crystal system. Scanning electron microscopy results show that morphologies of MnO2 films were clearly different. Among them, MnO2 film prepared in Mn(CH3COO)2 solution presented a lot of cracks and holes. According to electrochemical impedance spectrum analysis, this MnO2 film presents the lowest charge-transfer resistance. Additionally, electrochemical active surface areas of MnO2 films were calculated on the basis of equivalent circuit model for impedance data. The result was found that MnO2 film prepared in Mn(CH3COO)2 solution showed the biggest electrochemical active surface area, which was about 382 cm2. Cyclic voltammograms were carried out for all the samples. MnO2 film formed in Mn(CH3COO)2 solution showed the highest special capacitance of 230 F g-1. The results suggest that Mn(CH3COO)2 solution is suitable for electrodepositing MnO2 film using supercapacitor electrode materials.

scholarly journals Thickness-independent scalable high-performance Li-S batteries with high areal sulfur loading via electron-enriched carbon framework

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nana Wang ◽  
Xiao Zhang ◽  
Zhengyu Ju ◽  
Xingwen Yu ◽  
Yunxiao Wang ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
High Performance ◽  
Mechanical Stability ◽  
Electronic Conductivity ◽  
Active Surface ◽  
Charge Transfer Resistance ◽  
Active Surface Area ◽  
Free Standing ◽  
Transfer Resistance ◽  
Thickness Independent

AbstractIncreasing the energy density of lithium-sulfur batteries necessitates the maximization of their areal capacity, calling for thick electrodes with high sulfur loading and content. However, traditional thick electrodes often lead to sluggish ion transfer kinetics as well as decreased electronic conductivity and mechanical stability, leading to their thickness-dependent electrochemical performance. Here, free-standing and low-tortuosity N, O co-doped wood-like carbon frameworks decorated with carbon nanotubes forest (WLC-CNTs) are synthesized and used as host for enabling scalable high-performance Li-sulfur batteries. EIS-symmetric cell examinations demonstrate that the ionic resistance and charge-transfer resistance per unit electro-active surface area of S@WLC-CNTs do not change with the variation of thickness, allowing the thickness-independent electrochemical performance of Li-S batteries. With a thickness of up to 1200 µm and sulfur loading of 52.4 mg cm−2, the electrode displays a capacity of 692 mAh g−1 after 100 cycles at 0.1 C with a low E/S ratio of 6. Moreover, the WLC-CNTs framework can also be used as a host for lithium to suppress dendrite growth. With these specific lithiophilic and sulfiphilic features, Li-S full cells were assembled and exhibited long cycling stability.

scholarly journals New Generation of Electrochemical Sensors Based on Multi-Walled Carbon Nanotubes

2018 ◽  
Vol 8 (10) ◽  
pp. 1925 ◽  
Author(s):  
Thiago Oliveira ◽  
Simone Morais
Keyword(s):  
Carbon Nanotubes ◽  
Electrochemical Sensors ◽  
Industrial Applications ◽  
Charge Transfer Resistance ◽  
Active Surface Area ◽  
Synthesis Methods ◽  
Transfer Resistance ◽  
Multi Walled Carbon Nanotubes ◽  
New Generation ◽  
Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNT) have provided unprecedented advances in the design of electrochemical sensors. They are composed by sp2 carbon units oriented as multiple concentric tubes of rolled-up graphene, and present remarkable active surface area, chemical inertness, high strength, and low charge-transfer resistance in both aqueous and non-aqueous solutions. MWCNT are very versatile and have been boosting the development of a new generation of electrochemical sensors with application in medicine, pharmacology, food industry, forensic chemistry, and environmental fields. This work highlights the most important synthesis methods and relevant electrochemical properties of MWCNT for the construction of electrochemical sensors, and the numerous configurations and successful applications of these devices. Thousands of studies have been attesting to the exceptional electroanalytical performance of these devices, but there are still questions in MWCNT electrochemistry that deserve more investigation, aiming to provide new outlooks and advances in this field. Additionally, MWCNT-based sensors should be further explored for real industrial applications including for on-line quality control.

scholarly journals Characterization of Pt-Pd/C Electrocatalyst for Methanol Oxidation in Alkaline Medium

2011 ◽  
Vol 2011 ◽  
pp. 1-16 ◽  
Author(s):  
S. S. Mahapatra ◽  
J. Datta
Keyword(s):  
Methanol Oxidation ◽  
Electrode Surface ◽  
Electrochemical Impedance ◽  
Physicochemical Characterization ◽  
Charge Transfer Resistance ◽  
Graphite Substrate ◽  
Peak Current Density ◽  
Transfer Resistance ◽  
Alloyed Surface

The Pt-Pd/C electrocatalyst was synthesized on graphite substrate by the electrochemical codeposition technique. The physicochemical characterization of the catalyst was done by SEM, XRD, and EDX. The electrochemical characterization of the Pt-Pd/C catalyst for methanol electro-oxidation was studied over a range of NaOH and methanol concentrations using cyclic voltammetry, quasisteady-state polarization, chronoamperometry, and electrochemical impedance spectroscopy. The activity of methanol oxidation increased with pH due to better OH species coverage on the electrode surface. At methanol concentration (>1.0 M), there is no change in the oxidation peak current density because of excess methanol at the electrode surface and/or depletion of OH−at the electrode surface. The Pt-Pd/C catalyst shows good stability and the low value of Tafel slope and charge transfer resistance. The enhanced electrocatalytic activity of the electrodes is ascribed to the synergistic effect of higher electrochemical surface area, preferred OH−adsorption, and ad-atom contribution on the alloyed surface.

Electrochemical Assessment of X70 Steel With Non-Conventional Heat Treatment

MRS Advances ◽  
2017 ◽  
Vol 2 (50) ◽  
pp. 2819-2829
Author(s):  
L. R. Jacobo ◽  
R. García ◽  
V.H. López ◽  
A. Contreras
Keyword(s):  
Heat Treatment ◽  
Charge Transfer ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Polarization Curves ◽  
Localized Corrosion ◽  
Transfer Resistance ◽  
Internal Corrosion ◽  
Conventional Heat Treatment ◽  
A Charge

ABSTRACTCorrosion behavior of an API X70 steel by potentiodynamic polarization curves was carried out. X70 steel was heat treated at a temperature of 1050°C (onset temperature solution of niobium carbonitrides) for 15 and 30 minutes hold followed by quenching in water. Test solutions for electrochemical evaluation were NS4 solution and congenital water (CW) to assess external and internal corrosion pipelines respectively. The polarization curves were performed within a range of -500mV to 1000mV for NS4 solution and the -500mV to 600mV by congenital water respect to open circuit potential (OCP) at a scan rate of 1mV/s. The tests were conducted at room temperature. The surfaces of the samples were observed by scanning electron microscope (SEM). A localized corrosion type was observed. According to polarization curves it can be observed that oxidation reaction in the anodic branch belongs to a charge transfer process. Cathodic branches reveal a process where the charge transfer resistance is influenced by a process of mass transfer. The non-conventional heat treatment improved the corrosion resistance compared to as received material.

Recent Progress in Quantum Dots Based Nanocomposites Electrodes for Rechargeable Monovalent Metal-ion and Lithium Metal Batteries

2021 ◽  
Author(s):  
P. Rangaswamy ◽  
Ranjith Krishna Pai ◽  
Debasis Ghosh
Keyword(s):  
Metal Ion ◽  
Structural Integrity ◽  
Diffusion Path ◽  
Active Surface ◽  
Charge Transfer Resistance ◽  
Ion Diffusion ◽  
Transfer Resistance ◽  
Lithium Metal Batteries ◽  
Monovalent Metal ◽  
Low Charge

Engineering electrode architecture with an abundant active surface for charge storage, shorter ion diffusion path, low charge transfer resistance, and structural integrity against volume change during cycling are the key...

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