The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Baikun Li - One of the best experts on this subject based on the ideXlab platform.

  • cobalt porphyrin based material as methanol tolerant cathode in single chamber microbial fuel cells scmfcs
    Journal of Power Sources, 2014
    Co-Authors: Cristian Bruckner, Carlo Santoro, Yue Cheng, Baikun Li
    Abstract:

    This study focused on the development of novel cathode material based on the pyrolysis of [meso-tetrakis(2-thienyl)porphyrinato]Co(II) (CoTTP) for use in single chamber microbial fuel cells (SCMFCs) to treat wastewater containing methanol. The Cathodes produced at two loadings (0.5 and 1.0 mg cm � 2 ) were examined in batch mode SCMFCs treating methanol of different concentrations (ranging from 0.005 to 0.04 M) over a 900 h operational period. Methanol was completely removed in SCMFCs, and the cycle duration was prolonged at high methanol concentrations, indicating methanol was used as fuel in SCMFCs. Methanol had more poisoning effects to the traditional platinum (Pt) Cathodes than to the CoTTP Cathodes. Specifically, power generations from SCMFCs with Pt Cathodes gradually decreased over time, while the ones with CoTTP Cathodes remained stable, even at the highest methanol concentration (0.04 M). Cathode linear sweep voltammetry (LSVs) indicated that the electrocatalytic activity of the Pt cathode was suppressed by methanol. Higher CoTTP loadings had similar open circuit potential (OCP) but higher electrocatalytic activity than lower loadings. This study demonstrated that methanol can be codigested with wastewater and converted to power in MFCs, and a novel cathode CoTTP catalyst exhibits higher tolerance towards methanol compared with traditional Pt catalyst. Published by Elsevier B.V.

  • activated carbon nanofibers acnf as cathode for single chamber microbial fuel cells scmfcs
    Journal of Power Sources, 2013
    Co-Authors: Carlo Santoro, Astrid Stadlhofer, Viktor Hacker, G Squadrito, Uwe Schroder, Baikun Li
    Abstract:

    The suitability of carbon nanofibers (CNF) based Cathodes as alternative to the platinum (Pt)-based cathode in single chamber microbial fuel cells (SCMFCs) were extensively studied over 3-month operational period. MFCs were fed with two solutions: synthetic wastewater (phosphate buffer (PBS) plus sodium acetate) and real wastewater (mixed liquor suspendedsolid (MLSS) solution). CNFs were chemically activated using HNO3 and then hot pressed on a carbon cloth support to increase surface area. The cathode polarization showed a better behavior of the clean Pt-based cathode in abiotic conditions. The activation of the nanofibers (ACNFs) gave an advantage to the cathode performances compared to the raw CNFs. The SCMFCs fed with PBS showed four times higher power generation compared to MLSS solution. All the Cathodes showed a decrease in performances over time, and the advantage of the Pt over CNF/ACNF disappeared. CNF/ACNF Cathodes showed more stability in performances in long time operations. Biofilm formation, salt precipitations on the cathode, and the presence of hydrogen sulfide decreased the activity of Pt Cathodes. A degradation and Pt detachment were noticed on Pt Cathodes over time. In contrast, CNF/ACNF Cathodes exhibited less deterioration throughout the operational period, which demonstrated a great potential as cost-effective Cathodes for long-term operation.

Carlo Santoro - One of the best experts on this subject based on the ideXlab platform.

  • cobalt porphyrin based material as methanol tolerant cathode in single chamber microbial fuel cells scmfcs
    Journal of Power Sources, 2014
    Co-Authors: Cristian Bruckner, Carlo Santoro, Yue Cheng, Baikun Li
    Abstract:

    This study focused on the development of novel cathode material based on the pyrolysis of [meso-tetrakis(2-thienyl)porphyrinato]Co(II) (CoTTP) for use in single chamber microbial fuel cells (SCMFCs) to treat wastewater containing methanol. The Cathodes produced at two loadings (0.5 and 1.0 mg cm � 2 ) were examined in batch mode SCMFCs treating methanol of different concentrations (ranging from 0.005 to 0.04 M) over a 900 h operational period. Methanol was completely removed in SCMFCs, and the cycle duration was prolonged at high methanol concentrations, indicating methanol was used as fuel in SCMFCs. Methanol had more poisoning effects to the traditional platinum (Pt) Cathodes than to the CoTTP Cathodes. Specifically, power generations from SCMFCs with Pt Cathodes gradually decreased over time, while the ones with CoTTP Cathodes remained stable, even at the highest methanol concentration (0.04 M). Cathode linear sweep voltammetry (LSVs) indicated that the electrocatalytic activity of the Pt cathode was suppressed by methanol. Higher CoTTP loadings had similar open circuit potential (OCP) but higher electrocatalytic activity than lower loadings. This study demonstrated that methanol can be codigested with wastewater and converted to power in MFCs, and a novel cathode CoTTP catalyst exhibits higher tolerance towards methanol compared with traditional Pt catalyst. Published by Elsevier B.V.

  • activated carbon nanofibers acnf as cathode for single chamber microbial fuel cells scmfcs
    Journal of Power Sources, 2013
    Co-Authors: Carlo Santoro, Astrid Stadlhofer, Viktor Hacker, G Squadrito, Uwe Schroder, Baikun Li
    Abstract:

    The suitability of carbon nanofibers (CNF) based Cathodes as alternative to the platinum (Pt)-based cathode in single chamber microbial fuel cells (SCMFCs) were extensively studied over 3-month operational period. MFCs were fed with two solutions: synthetic wastewater (phosphate buffer (PBS) plus sodium acetate) and real wastewater (mixed liquor suspendedsolid (MLSS) solution). CNFs were chemically activated using HNO3 and then hot pressed on a carbon cloth support to increase surface area. The cathode polarization showed a better behavior of the clean Pt-based cathode in abiotic conditions. The activation of the nanofibers (ACNFs) gave an advantage to the cathode performances compared to the raw CNFs. The SCMFCs fed with PBS showed four times higher power generation compared to MLSS solution. All the Cathodes showed a decrease in performances over time, and the advantage of the Pt over CNF/ACNF disappeared. CNF/ACNF Cathodes showed more stability in performances in long time operations. Biofilm formation, salt precipitations on the cathode, and the presence of hydrogen sulfide decreased the activity of Pt Cathodes. A degradation and Pt detachment were noticed on Pt Cathodes over time. In contrast, CNF/ACNF Cathodes exhibited less deterioration throughout the operational period, which demonstrated a great potential as cost-effective Cathodes for long-term operation.

Joachim Heberlein - One of the best experts on this subject based on the ideXlab platform.

  • an experimental investigation of factors affecting arc cathode erosion
    Journal of Physics D, 1998
    Co-Authors: Joachim Heberlein
    Abstract:

    A specially designed thermal plasma reactor system for the investigation of arc-cathode erosion has been set up. By using an OMA-spectrometer system, emission spectroscopic measurements of electron temperature and electron number density in the cathode region have been performed, together with single-colour and two-colour pyrometry of cathode temperature distributions. Observation of cathode spot behaviour has been carried out simultaneously by employing a telemicroscope and a high-speed vision system. Cathodes have been examined by SEM and EDX after arcing. For pure tungsten Cathodes, the initial cathode geometry has almost no effect on the cathode spot's behaviour due to the molten state of the cathode spot. The major erosion mechanism is the ejection of liquid droplets from the cathode spot. However, the initial cathode geometry has a certain influence on the cathode's erosion for 2% thoriated tungsten Cathodes. A highly non-uniform erosion pattern will occur if the cathode is overcooled, probably due to ion bombardment in the low-temperature regions of the arc-attachment spot.

  • Characterization of the arc cathode attachment by emission spectroscopy and comparison to theoretical predictions
    Plasma Chemistry and Plasma Processing, 1995
    Co-Authors: X. Zhou, Joachim Heberlein
    Abstract:

    Emission spectroscopic diagnostics of electron temperature distribution and electron number density distribution in the cathode region have been carried out employing an OMA/spectrometer system. Single color and two color pyrometry of cathode temperature distributions have also been performed. The experimental results are compared with results of a theoretical model formulated previously to study the arc cathode interaction. The results show that the plasma in the cathode region strongly deviates from LTE. Thermionic cooling is the major cooling mechanism of Cathodes at high arc currents. The work function of 2% thoriated tungsten Cathodes increases during arcing due to fast evaporation of thorium from 2% thoriated tungsten Cathodes.

Hatem Akbulut - One of the best experts on this subject based on the ideXlab platform.

  • Electrochemical evaluation of different graphene/sulfur composite synthesis routes in all-solid-state lithium-sulfur batteries
    Journal of Solid State Electrochemistry, 2020
    Co-Authors: Abdulkadir Kızılaslan, Hatem Akbulut
    Abstract:

    The preparation of different cathode composites with intimate contact between the components is of great importance to obtain batteries with better electrochemical performance. Among different cathode systems, graphene-sulfur composites are widely utilized in lithium-sulfur batteries and their electrochemical performances are directly linked to syntheses methods. In this study, graphene-sulfur composite Cathodes were prepared by three distinct routes and their performances were evaluated in all-solid-state lithium-sulfur batteries where the lithium and Li_7P_3S_11 were utilized as anode and solid electrolyte, respectively. Our results indicate that Cathodes prepared by solution-based techniques were found to impart higher capacity and cycling stability compared with cathode prepared by the melt-diffusion method. Better performance was attributed to fine and homogeneously distributed particles obtained in Cathodes prepared by solution-based techniques. Besides, higher capacity was acquired in the Cathodes where the sulfur was obtained through reduction from Na_2S_2O_3 instead of utilizing sulfur in elemental powder form. Among three different Cathodes synthesized by different routes, the best performance was gained in the cathode prepared by sulfur-amine chemistry method where the sulfur was obtained by reduction from Na_2S_2O_3 with 970 mAh g^-1 and 795 mAh g^-1 initial and after 200 cycles discharge capacity respectively. Our results indicate the significance of particle size and intimate contact between components on the electrochemical performance of the sulfur-based Cathodes and the synthesis route to follow for high-performance all-solid-state lithium-sulfur batteries.

Johanna Rosen - One of the best experts on this subject based on the ideXlab platform.

  • effect of mo cu cathode composition on process stability macroparticle formation plasma generation and thin film deposition in dc arc synthesis
    Journal of Applied Physics, 2020
    Co-Authors: Igor Zhirkov, Peter Polcik, Andrejs Petruhins, Szilard Kolozsvári, Johanna Rosen
    Abstract:

    In this work, we present the correlation between cathode composition and features of the arcing process for Mo1 − xCux [x = 0.0, 0.07 (0.05), 0.14 (0.10), 0.21 (0.15), 0.40 (0.3), 0.73 (0.63), 0.97 (0.95), and 1.00, atomic fraction (weight fraction)] Cathodes used in a DC vacuum-arc deposition system. It is found that the stability of the arcing process crucially depends on the cathode composition. The most stable arc spot and the lowest cathode potential (∼19 V) are detected for the Mo0.27Cu0.73 cathode, while the Mo0.93Cu0.07 cathode shows the most unstable arcing process with the highest cathode potential (∼28 V). The properties of the generated plasma are also strongly dependent on the relative ratio of the cathode elements. The metal ions from the Mo and Cu Cathodes have peak kinetic energies around 136 and 62 eV, respectively, while for a Mo0.79Cu0.21 cathode, the corresponding energies are only 45 and 28 eV. The average charge states decreased from 2.1 to 1.6 for Mo ions and from 2 to 1.2 for Cu ions. The intensity of macroparticle generation and the size of the droplets correlate with the relative fraction of Cu. However, it is shown that, typically for the Cathodes with a low amount of Cu, an increased abundance of visually observed macroparticles leads to droplet-free films. The film thicknesses and their compositions also demonstrate dependencies on the elemental composition of the cathode. These results are discussed in the light of no solubility between Mo and Cu and the high temperature of the cathode surface during the arcing process.

  • Effect of Ti-Al cathode grain size on plasma generation and thin film synthesis from a direct current vacuum arc plasma source
    AIP Publishing LLC, 2019
    Co-Authors: Igor Zhirkov, Peter Polcik, Andrejs Petruhins, Szilard Kolozsvári, Johanna Rosen
    Abstract:

    Herein, we investigate the influence of powder metallurgical manufactured Ti0.5Al0.5 cathode grain size (45-150 μm) on the properties of a DC arc discharge, for N2 pressures in the range 10-5 Torr (base pressure) up to 3x10-2 Torr. Intermetallic TiAl Cathodes are also studied. The arc plasma is characterized with respect to ion composition, ion charge state, and ion energy, and is found to change with pressure, independent on choice of cathode. Scanning electron microscopy, X-ray diffraction, and Energy-dispersive X-ray spectroscopy of the cathode surfaces and the concurrently deposited films are used for exploring the correlation between cathode-, plasma-, and film composition. The plasma has a dominating Al ion content at elevated pressures, while the film composition is consistent with the cathode composition, independent on cathode grain size. Cross-sections of the used Cathodes are studied, and presence of a converted layer, up to 10 μm, is shown, with an improved intermixing of the elements on the cathode surface. This layer is primarily explained by condensation of cathode material from the melting and splashes accompanying the arc spot movement, as well as generated plasma ions being redeposited upon returning to the cathode. The overall lack of dependence on grain size is likely due to similar physical properties of Ti, Al and TiAl grains, as well as the formation of a converted layer. The presented findings are of importance for large scale manufacturing and usage of Ti-Al Cathodes in industrial processes