Papers by Keyword: Oxygen Reduction

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Authors: Jian Min Zhang, Wei Hua Chen
Abstract: A new composite electrocatalyst, well-dispersed TiO2/active carbon (AC), has been assessed with regard to its applicability for oxygen reduction in air electrodes. TiO2/AC powders were prepared by one-step vapor hydrolysis of TiCl4 with active carbon. The structure and composition of the powders were analyzed by means of XRD and FTIR, and the results showed that anatase titanium dioxide of particle size 16.5 nm was produced after calcination at 400 °C. The influences of the preparative parameters of the air electrode on its discharge performance were studied by polarization curve measurements. The terminal voltage of the air battery was maintained at above 1.05 V while the current density of the air electrodes reached 150 mA cm-2. These results show that the composite catalyst has high electrochemical activity for the oxygen reduction reaction.
Authors: Feng Ying Chen, Ke Zhi Li, He Jun Li
Abstract: Acid-functionalized multiwalled carbon nanotube (AF-MWCNT)-supported tetranitro-copper phthalocyanine (TNCuPc) assemblies were prepared by solid phase synthesis method. The products were characterized by infrared spectroscopy, scanning electron microscopy and XRD. The electrocatalytic activity of the obtained AF-MWCNT-supported TNCuPc assemblies was measured by cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques in an oxygen-saturated 0.1 M KOH. The results showed that the catalytic activity of TNCuPc/AF-MWCNTs towards oxygen reduction was a two-step, two-electron process for oxygen reduction.
Authors: Volodymyr Khomenko, Kostiantyn Lykhnytskyi, Viacheslav Barsukov, Vitalii Chaban
Abstract: Electrochemical properties and possibilities of manufacturing the anodes based on water-soluble binders such as carboxymethylcellulose (CMC) have been investigated in order to create prerequisites for development of “green” technologies for recyclability of LIBs components.In this work an advanced anode was designed. A kind of nanosized carbon coated Si composite was synthesized. The charge/discharge test reveals that the advanced anode shows a reversible capacity of 600 mAh/g. The improved performance was ascribed to the carbon shell of Si and CMC binder. The binder CMC buffers the expansion of the Si and the improved electric contact between the active material and copper current collector.
Authors: Sara Cavaliere, Frédéric Raynal, Arnaud Etcheberry, Michel Herlem, Henri Perez
Abstract: 4-mercaptoaniline functionalised platinum particles of 2 nm diameter were synthesised and over-grafted with 2-thiophenecarbonyl chloride. The derivative particles were dispersed in DMSO and gave long term stable suspensions. The Langmuir-Blodgett technique was then used to build up stable Langmuir-Blodgett films and the electrochemical behaviour of these ultra-thin films towards oxygen reduction was investigated in an acidic medium. It revealed direct activity without any previous activation treatments despite of the presence of the organic shell at the particle surface. Furthermore, XPS experiments revealed that the organic crown was not significantly destroyed on prolonged cycling. The results open a way to study original and versatile platinum-based nanocomposites.
Authors: Yi Li, Jian Liu, Chun Lei Wang, Wen Bin Su, Yuan Hu Zhu, Ji Chao Li, Liang Mo Mei
Abstract: The thermoelectric properties of Sr0.61Ba0.39Nb2O6 ceramics, reduced in various conditions, were investigated in the temperature range from 323K to 1073K. Both the electrical resistivity and the absolute Seebeck coefficient decreased with the deepening degree of oxygen-reduction. However, the decrease of the electrical resistivity had a major influence on the thermoelectric power factor. Therefore, the more heavily reduced sample can gain the higher value of thermoelectric power factor. It has been observed that the thermal conductivity increased with the deepening degree of oxygen-reduction, which indicates that the scattering of the oxygen vacancies produced by reduction does not play a dominant role in the thermal conduction. In spite of the increase of the thermal conductivity, the oxygen-reduction still promoted the thermoelectric figure of merit via the increase of the thermoelectric power factor. And the most heavily reduced Sr0.61Ba0.39Nb2O6 ceramic has the highest thermoelectric figure of merit (~0.18 at 1073 K) among all the samples.
Authors: Kenji Yoshihara, Takeshi Chuma, Morihiro Saito, Jun Kuwano, Hidenobu Shiroishi
Abstract: The O2-gas electrode (OGE) properties of the pyrochlores Pb2Ru2-XMXO7-δ(M=Mn,Fe,Co,Ni) [PRMx] were examined below 300°C with the cell of the type (PRMx | Ba0.975Ce0.8Gd0.2O3 (BCG) | PRMx). The PRMn electrodes showed good OGE properties comparable to those of Pb2Ru2O6.5 and superior to those of a Pt-paste electrode and the La0.6Sr0.4Co0.98Ni0.02O3 electrode, which are well-known representative OGEs. The results indicate that the PRMn electrodes can be used for OGEs in low-temperature applications including oxygen sensors.
Authors: Kenji Yoshihara, Yoshinobu Saito, Morihiro Saito, Jun Kuwano, Hidenobu Shiroishi
Abstract: The activities of the pyrochlores Pb2Ru2-xMxO7-δ (M=Mn,Fe,Co,Ni)[PRM(0x)] toward electrochemical oxygen reduction (EOR) were examined in 0.1 M KOH and 0.05 M H2SO4 aqueous solutions. The onset voltage (Vo) and the efficiency (E4) of 4-electron reduction of oxygen for PRM(0x) were evaluated by semi-steady state voltammetry with rotating ring-disk electrodes. In PRM01, the order of the EOR activities was PRMn01 > PRCo01 > PRNi01 > PRFe01 in both solutions. This was consistent with the variation of the lattice parameters, i.e. PRM01 with a smaller lattice parameter showed higher EOR activity. In addition, PRMn05 showed higher EOR activity than PRMn01. The onset voltages Vo were 0.95 and 0.50 V vs. reversible hydrogen electrode in 0.1 M KOH and 0.05 M H2SO4, respectively, while E4 was almost 100 % in both solutions. These results indicate that the EOR activity of PRM(0x) depends on the incorporated metal ions on the B-sites and their contents.
Authors: Diogo M.F. Santos, César A.C. Sequeira
Abstract: The electrocatalysis of the oxygen reduction reaction by Lanthanum Barium Manganate, (La0.5Ba0.5MnO3) (LBM) has been studied by cyclic voltammetry using the rotating ring-disc electrode technique (RRDE) in alkaline medium. From the ring-disc data and other kinetic parameters it has been assumed that the oxygen reduction occurs by dissociative chemisorption at low overpotentials. At higher overpotentials, the formation of hydrogen peroxide (HO2 - in this case) has been observed on this electrocatalyst. The apparent exchange current density value for oxygen reduction on LBM has been found to be 4 x 10-8 Acm-2, while the corresponding Tafel slope is 0.115 V per decade. The possible reaction mechanism for electroreduction of oxygen on this oxide catalyst has been discussed.
Authors: Sen Liu, Jin Hua Lu, He Jun Li, Ying Bo Fei
Abstract: Iron tetrapyrazinoporphyrazine (FePTpz) and cobalt tetrapyrazinoporphyrazines (CoPTpz) supported on multiwalled carbon nanotubes (MWCNTs) are prepared by solid phase synthesis method. The products are characterized by scanning and transmission electron microscopy. The electrocatalytic activity of the obtained MWCNTs-supported FePTpz and CoPTpz assemblies (MPTpz/MWCNTs) is measured by cyclic voltammetry and rotating disk electrode techniques in an oxygen-saturated 0.1M KOH. The results show that MPTpz/MWCNTs are more efficient than reference MPTpz. FePTpz/MWCNTs are more efficient for O2 reduction than CoPTpz/MWCNTs, both of FePTpz/MWCNTs and CoPTpz/MWCNTs exhibit a one-step, four-electron pathway for ORR.
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