Electrocatalytic hydrogenation of phenol on various electrode materials

1997 ◽  
Vol 75 (12) ◽  
pp. 1862-1867 ◽  
Author(s):  
Anna Martel ◽  
Behzad Mahdavi ◽  
Jean Lessard ◽  
Hugues Ménard ◽  
Louis Brossard
Keyword(s):  
Sodium Chloride ◽  
Current Efficiency ◽  
Raney Nickel ◽  
Current Density ◽  
Electrode Materials ◽  
Supporting Electrolyte ◽  
Current Control ◽  
Electrocatalytic Hydrogenation ◽  
Nickel Particles ◽  
A Current

The electrocatalytic hydrogenation (ECH) of phenol was investigated at room temperature under galvanostatic control in aqueous sulfuric acid solutions on platinized platinum (Pt/Pt) electrodes and on composite Rh/Ni and Ru/Ni electrodes consisting of rhodium or ruthenium chemically deposited on nickel particles dispersed in a lanthanum polyphosphate matrix. The order of electrocatalytic activity at a current density (based on the geometric area) of 1 mA/cm2 was found to be Ru/Ni > Pt/Pt > Rh/Ni. The efficiency decreased with increased current density. For the Ru/Ni electrodes, the efficiency increased with the percentage of Ru (2.3 to 5%). On Ru 5%/Ni electrodes and at a current density of 5 mA/cm2, cyclohexanol was obtained with a high selectivity of 91 % and a current efficiency of 23% after 94% conversion. In neutral aqueous boric acid containing sodium chloride as supporting electrolyte, the Rh/Ni and Ru/Ni electrodes showed very low activity. The influence of the supporting electrolyte, periodic current control, and temperature was studied in the neutral medium with composite Raney nickel (RaNi) electrodes consisting of Raney nickel particles dispersed in a nickel matrix. At 60 °C and a current density of 10 mA/cm2, the selectivity of cyclohexanol formation was 100% with a 11% current efficiency after 92% conversion with sodium chloride as supporting electrolyte. Keywords: electrocatalytic hydrogenation, phenol, ruthenium on nickel cathodes, rhodium on nickel cathodes, Raney nickel cathodes.

scholarly journals A Hierarchical Architecture of Functionalized Polyaniline/Manganese Dioxide Composite with Stable-Enhanced Electrochemical Performance

2021 ◽  
Vol 5 (5) ◽  
pp. 129
Author(s):  
Yapeng Wang ◽  
Yanxiang Wang ◽  
Chengjuan Wang ◽  
Yongbo Wang
Keyword(s):  
Electrochemical Performance ◽  
Manganese Dioxide ◽  
Specific Capacitance ◽  
Current Density ◽  
Electrode Materials ◽  
High Efficiency ◽  
Scanning Speed ◽  
Hierarchical Architecture ◽  
Electrochemical Window ◽  
A Current

As one of the most outstanding high-efficiency and environmentally friendly energy storage devices, the supercapacitor has received extensive attention across the world. As a member of transition metal oxides widely used in electrode materials, manganese dioxide (MnO2) has a huge development potential due to its excellent theoretical capacitance value and large electrochemical window. In this paper, MnO2 was prepared at different temperatures by a liquid phase precipitation method, and polyaniline/manganese dioxide (PANI/MnO2) composite materials were further prepared in a MnO2 suspension. MnO2 and PANI/MnO2 synthesized at a temperature of 40 °C exhibit the best electrochemical performance. The specific capacitance of the sample MnO2-40 is 254.9 F/g at a scanning speed of 5 mV/s and the specific capacitance is 241.6 F/g at a current density of 1 A/g. The specific capacitance value of the sample PANI/MnO2-40 is 323.7 F/g at a scanning speed of 5 mV/s, and the specific capacitance is 291.7 F/g at a current density of 1 A/g, and both of them are higher than the specific capacitance value of MnO2. This is because the δ-MnO2 synthesized at 40 °C has a layered structure, which has a large specific surface area and can accommodate enough electrolyte ions to participate the electrochemical reaction, thus providing sufficient specific capacitance.

scholarly journals Electrochemical Features of Symmetric and Asymmetric Supercapacitors Based on Nanostructured Mn-Cuo Electrodes

2018 ◽  
Vol 34 (6) ◽  
pp. 3058-3063 ◽  
Author(s):  
R. Suresh ◽  
K. Tamilarasan ◽  
D. Senthil Vadivu
Keyword(s):  
Current Density ◽  
Material Science ◽  
Electrode Materials ◽  
Aqueous Electrolyte ◽  
Cyclic Stability ◽  
Initial Value ◽  
Asymmetric Supercapacitors ◽  
Supercapacitive Performance ◽  
Subsequent Investigation ◽  
A Current

Progress in material science has unearthed a number of options that offer great advantages for nanostructured electrode materials which enable supercapacitors to operate efficiently. Present work involves fabrication of symmetric and asymmetric type supercapacitor devices utilizing Mn-CuO nanostructures and activated carbon (AC) as electrode materials and subsequent investigation on their supercapacitive performance in 2M KOH aqueous electrolyte. The asymmetric supercapacitor device (Mn-CuO // 2M KOH// AC) demonstrate a specific capacitance of 72 Fg-1 at a current density of 0.5 Ag-1. The cyclic stability test of this device performed at a current density of 10 Ag-1 reveals a capacitance retention of 71% of its initial value over 300 charge-discharge cycles. In addition, this device exhibits an energy density of 7.4 Whkg-1 and a power density of 127 Wkg-1.

The electrocatalytic hydrogenation of fused poly cyclic aromatic compounds at Raney nickel electrodes: the influence of catalyst activation and electrolysis conditions

1990 ◽  
Vol 68 (7) ◽  
pp. 1218-1227 ◽  
Author(s):  
Denis Robin ◽  
Michel Comtois ◽  
Anna Martel ◽  
René Lemieux ◽  
Amoy Kam Cheong ◽  
...  
Keyword(s):  
Raney Nickel ◽  
Supporting Electrolyte ◽  
Aqueous Sodium Hydroxide ◽  
Constant Current ◽  
Electrocatalytic Hydrogenation ◽  
Catalyst Activation ◽  
Nickel Electrodes ◽  
Initial Ph ◽  
Raney Ni ◽  
Tetrabutylammonium Chloride

The electrocatalytic hydrogenation (ECH) of phenanthrene, anthracene, and naphthalene has been investigated under constant current at Raney nickel electrodes in a mixed aqueous organic medium. The influence of various parameters on the efficiency of the process determined by the current efficiency (a measure of the competition between hydrogenation and hydrogen evolution, the only two electrochemical processes occurring), the extent of hydrogenation (yield of octahydro-derivatives), and the conversion rate was studied with phenanthrene. The best conditions were ethylene glycol or propylene glycol as cosolvent containing between 1.5 to 5% of water, a neutral or slightly acidic medium containing boric acid (0.1 M) as buffer (initial pH of 2.6, final pH of 6.0–6.2), sodium chloride or tetrabutylammonium chloride as supporting electrolyte, a temperature of 80° C, and a current density of 42 to 84 mA/cm2. The most active electrodes (consisting of Raney Ni particles dispersed in a nickel matrix and surrounded by a layer of porous nickel) were obtained by leaching the dispersed alloy particles at 75 °C for 7 h in 30% aqueous sodium hydroxide. The electrohydrogenation stopped at derivatives with a single aromatic ring, namely the octahydrophenanthrenes, octahydroanthracenes, and tetralin. In a non-buffered medium, tetrahydrophenanthrene could be obtained with selectivities of 80% or better. Keywords: electrocatalytic hydrogenation, Raney nickel electrodes, phenanthrene, anthracene, naphthalene.

Electrochemical Oxidation of Azo Dye Wastewater Using Graphene-Based Electrode Materials

2019 ◽  
Vol 19 (11) ◽  
pp. 7308-7314
Author(s):  
Jinyan Li ◽  
Qingsong Guan ◽  
Junming Hong ◽  
Chang-Tang Chang
Keyword(s):  
Electrochemical Oxidation ◽  
Current Density ◽  
Electrode Materials ◽  
Supporting Electrolyte ◽  
Performance Comparison ◽  
Carbon Cloth ◽  
Reactive Black 5 ◽  
Dye Wastewater ◽  
Composite Electrodes ◽  
Initial Concentration

Composite electrodes with different graphene (GN)/TiO2 ratios and nano-activated carbon electrodes were prepared for electrocatalytic performance comparison. The electrodes were loaded with platinum (Pt) by use of chloroplatinic acid to promote their performance. Reactive Black 5 (RBk5) dye wastewater was treated as a challenging pollutant by use of advanced electrochemical oxidation technology. The composite materials were characterized by Transmission Electron Microscope (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), and Energy Disperse Spectroscopy (EDS). Results showed that the graphene electrode was prepared successfully and verified because all elements were uniformly loaded on the conductive carbon cloth. The effects of several operating parameters including material types, pH, initial concentration of RBk5, and current density on the removal performance of RBk5 were also assessed. The supporting electrolyte was NaCl solution of 1 g L−1. The concentration of RBk5 was detected using an ultraviolet spectrophotometer with a detection wavelength of 600 nm. The optimum parameters of the experiment were GN/TiO2 ratio of 1:4 and pH of 6.6. The removal efficiency of RBk5 could be higher than 95% under an initial concentration of RBk5 of 5 ppm and a current density of 2.5 mA·cm-2 when reaction time was 30 min.

Hierarchical Dendritic Polypyrrole with High Specific Capacitance for High-performance Supercapacitor Electrode Materials

2017 ◽  
Vol 20 (4) ◽  
pp. 197-204
Author(s):  
Weiliang Chen ◽  
Shuhua Pang ◽  
Zheng Liu ◽  
Zhewei Yang ◽  
Xin Fan ◽  
...  
Keyword(s):  
Specific Capacitance ◽  
Current Density ◽  
High Performance ◽  
Electrode Materials ◽  
High Specific Capacitance ◽  
Chemical Oxidation ◽  
Channel Structure ◽  
Supercapacitor Electrode ◽  
Infrared Spectrometer ◽  
A Current

Polypyrrole with hierarchical dendritic structures assembled with cauliflower-like structure of nanospheres, was synthesized by chemical oxidation polymerization. The structure of polyryrrole was characterized by Fourier transform infrared spectrometer and scanning electron microscopy. The electrochemical performance was performed on CHI660 electrochemical workstation. The results show that oxalic acid has a significant effect on morphology of PPy products. The hierarchical dendritic PPyOA(3) electrodes possess a large specific capacitance as high as 744 F/g at a current density of 0.2 A/g and could achieve a higher specific capacitance of 362 F/g even at a current density of 5.0 A/g. Moreover, the dendritic PPy products produce a large surface area on the electrode through the formation of the channel structure with their assembled cauliflower-like morphology, which facilitates the charge/electron transfer relative to the spherical PPy electrode. The spherical dendritic PPyOA(3) electrode has 58% retention of initial specific capacitance after 260 cycles. The as-prepared dendritic polypyrrole with high performance is a promsing electrode material for supercapacitor.

scholarly journals Asymmetric Pseudocapacitors Based on Interfacial Engineering of Vanadium Nitride Hybrids

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1141 ◽  
Author(s):  
Hailan Su ◽  
Tuzhi Xiong ◽  
Qirong Tan ◽  
Fang Yang ◽  
Paul B. S. Appadurai ◽  
...  
Keyword(s):  
Current Density ◽  
High Performance ◽  
Electrode Materials ◽  
Vanadium Nitride ◽  
Mos2 Nanosheets ◽  
Energy Storage Devices ◽  
Storage Devices ◽  
Areal Capacitance ◽  
Interfacial Engineering ◽  
A Current

Vanadium nitride (VN) shows promising electrochemical properties as an energy storage devices electrode, specifically in supercapacitors. However, the pseudocapacitive charge storage in aqueous electrolytes shows mediocre performance. Herein, we judiciously demonstrate an impressive pseudocapacitor performance by hybridizing VN nanowires with pseudocapacitive 2D-layered MoS2 nanosheets. Arising from the interfacial engineering and pseudocapacitive synergistic effect between the VN and MoS2, the areal capacitance of VN/MoS2 hybrid reaches 3187.30 mF cm−2, which is sevenfold higher than the pristine VN (447.28 mF cm−2) at a current density of 2.0 mA cm−2. In addition, an asymmetric pseudocapacitor assembled based on VN/MoS2 anode and TiN coated with MnO2 (TiN/MnO2) cathode achieves a remarkable volumetric capacitance of 4.52 F cm−3 and energy density of 2.24 mWh cm−3 at a current density of 6.0 mA cm−2. This work opens a new opportunity for the development of high-performance electrodes in unfavorable electrolytes towards designing high areal-capacitance electrode materials for supercapacitors and beyond.

Amorphous and Crystalline TiO2 Nanotube Arrays for Enhanced Li-ion Intercalation Properties

2010 ◽  
Vol 1266 ◽  
Author(s):  
Dongsheng Guan ◽  
Chuan Cai ◽  
Ying Wang
Keyword(s):  
Current Density ◽  
Electrode Materials ◽  
Nanotube Arrays ◽  
Outer Diameter ◽  
Compact Layer ◽  
Self Organized ◽  
Battery Electrode ◽  
Li Ion ◽  
Ion Intercalation ◽  
A Current

AbstractWe have employed anodic oxidation of Ti foils to prepare self-organized TiO2 nanotube arrays which show enhanced electrochemical properties for applications as Li-ion battery electrode materials. The lengths and pore diameters of TiO2 nanotubes can be finely tuned by varying voltage, electrolyte composition, or anodization time. The as-prepared nanotubes are amorphous and can be converted into anatase nanotubes with heat treatment at 480oC and nanotubes of mixed anatase/rutile phases by heating at 580oC. The morphological features of nanotubes remain unchanged after annealing. Amorphous nanotubes with a length of 3.0 μm and an outer diameter of 125 nm delivers a capacity of 91.2 μA h cm-2 at a current density of 400 μA cm-2, while those with a length of 25 μm and an outer diameter of 158 nm display a capacity of 533 μA h cm-2. The 3-μm long anatase nanotubes and nanotubes of mixed phases show lower capacities of 53.8 μA h cm-2 and 63.1 μA h cm-2, respectively at the same current density. The amorphous TiO2 nanotubes with a length of 1.9 μm exhibit a capacity five times higher than that of TiO2 compact layer even when the nanotube array is cycled at a current density 80 times higher than that for the compact layer. The amorphous nanotubes show excellent capacity retention ability over 50 cycles. Cycled nanotubes show little change in morphology compared to the nanotubes before cycling, indicating the high structural stability of TiO2 nanotubes.

Preparation of CMC-PVA/PAN-FePc(COOH)8/CS-PVA Bipolar Membrane and its Application in Electro-Oxidized Synthesis of Dialdehydle Starch

2015 ◽  
Vol 1120-1121 ◽  
pp. 141-147
Author(s):  
Zhong Gui Li ◽  
Ting Jin Zhou ◽  
Ri Yao Chen ◽  
Xiao Chen ◽  
Xi Zheng ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Current Efficiency ◽  
Current Density ◽  
Cell Voltage ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Experimental Results ◽  
Bipolar Membrane ◽  
Electrospinning Technique ◽  
A Current

The polyacrylonitrile (PAN)-iron octocarboxyphthalocyanine (FePc(COOH)8) nanofibers were prepared using electrospinning technique and introduced into the interlayer of a carboxymethyl cellulose (CMC)-polyvinyl alcohol (PVA)/chitosan (CS)-polyvinyl alcohol bipolar membrane (BPM), which was characterized using SEM, contact angle measurement, current-voltage characteristics, AC impedance spectroscopy and so on. The experimental results showed that after modification by PAN-FePc(COOH)8 nanofibers, the membrane impedance of the BPM and its cell voltage were decreased. That indicated that the water splitting efficiency in the interlayer of the BPM was increased. Then the prepared CMC-PVA/PAN-FePc(COOH)8/CS-PVA BPM was used in the electro-oxidized preparation of dialdehydle starch (DAS). The experimental results indicated that a current density of 20mA·cm-2 was suitable to obtain high current efficiency. When the electrolysis time was 3h at a current density of 20 mA·cm-2 , the current efficiency of the CMC-PVA/PAN-FePc(COOH)8/CS-PVA BPM-equipped cell was as high as 67%.

Partially Graphitized Iron-Carbon Hybrid Composite as Electrochemical Supercapacitor Material

2020 ◽  
Author(s):  
Sai Rashmi M. ◽  
Ashish Singh ◽  
Chandra sekhar Rout ◽  
Akshaya Samal ◽  
Manav Saxena
Keyword(s):  
Iron Oxide ◽  
Current Density ◽  
Electrode Material ◽  
High Performance ◽  
Electrode Materials ◽  
Carbon Composite ◽  
X Ray ◽  
Transmission Electron ◽  
Excellent Property ◽  
A Current

<p>The conversion of biomass into valuable carbon composites as an efficient non-precious energy storage electrode material have elicited extensive research interest. As synthesized partially graphitized iron oxide-carbon composite material (Fe<sub>3</sub>O<sub>4</sub>/Fe<sub>3</sub>C@C) shows an excellent property as an electrode material for supercapacitor. X-ray diffraction, High resolution transmission electron microscopy, X-ray photo-electron spectroscopy and Brunauer-Emmett-Teller analysis is used to study the structural, compositional and surface areal properties. The electrode material shows a specific surface area of 827.4 m<sup>2</sup>/g. Due to the synergistic effect of graphitic layers with iron oxide/carbide, Fe<sub>3</sub>O<sub>4</sub>/Fe<sub>3</sub>C@C hybrid electrode materials display high-performance for supercapacitor with excellent capacity of 878 F/g at a current density of 5A/g (3-electrode) and 211.6 F/g at a current density of 0.4A/g (2-electrode) in 6M KOH electrolyte with good cyclic stability.</p>

Sign in / Sign up

Export Citation Format

Share Document