Structural and electrochemical characterization of tin-containing graphite compounds used as anodes for Li-ion batteries

Two tin–graphite composites (“core-shell” structures) with different metal content (80 wt% and 20 wt%) as well as their structural and electrochemical characteristics are presented. Mitsubishi's synthetic carbon was used as starting material for the modification experiments. Chemical reduction was applied for the coating process, which was carried out under inert argon atmosphere. Although a homogeneous film of the nanoscale tin particles (∼60 nm) have been achieved, the electrochemical performance improvement strongly depends on the thickness of the “shell’ layer and the progressively increased active surface area together with the tin metal contents. The electrode with low metal concentration displayed both improved cycling performance and stable discharge capacity of 435 Ah kg⁻¹ compared with untreated graphite electrode. The tin-rich composite shows a higher medial discharge capacity (540 mAh g⁻¹) but increased capacity fading, while higher metal contents lead to bulk-coated film with disassociated and agglomerated tin nanoparticles as well as higher surface area and likely presence of oxide impurities.     

Lithium intercalation and interfacial kinetics of composite anodes formed by oxidized graphite and copper

The electrochemical behavior of composite anodes prepared either by mixing partially oxidized graphite and Cu powders or by coating the pristine partially oxidized graphite electrodes with few-nanometer-thick Cu layers has been studied by slow-scan-rate cyclic voltammetry (SSCV) and galvanostatic charge/discharge cycles over the temperature range of −30 °C to 20 °C. The interfacial intercalation/deintercalation kinetics has also been investigated using electrochemical impedance spectroscopy (EIS).     

Simultaneous hydrogen production and pollutant degradation by photocatalysis of wastewater using liquid phase plasma

Ethanolamine released from a nuclear power plant was degraded by photocatalytic decomposition using plasma in the liquid phase with metal-incorporated photocatalysts. Metal-incorporated titanium dioxide photocatalysts were employed with carbon nanotubes and carbon nanofibers as a support. The photocatalytic decomposition of ethanol amine-contained water induced the degradation of ethanolamine and H₂ evolution, simultaneously. The degradation of ethanolamine and H₂ evolution were elevated by incorporating Ni on titanium dioxide nanocrystallites. The rate of H₂ evolution in the ethanolamine-containing water was higher than that in pure water, which was attributed to the additional H₂ evolution by the photodecomposition of ethanolamine in water.     

Microstructural and electrochemical impedance study of nickel-Ce0.9Gd0.1O1.95 anodes for solid oxide fuel cells fabricated by ultrasonic spray pyrolysis

Optimization of the electrode microstructure in a solid oxide fuel cell (SOFC) is an important approach to performance enhancement. In this study, the relationship between the microstructure and electrochemical performance of an anode electrode fabricated by ultrasonic spray pyrolysis was investigated. Nickel-Ce_0.9Gd_0.1O_1.95 (Ni-CGO) anodes were deposited on a dense yttria stabilized zirconia (YSZ) substrate by ultrasonic spray pyrolysis, and the resulting microstructure was analyzed. Scanning electron microscope (SEM) examinations revealed the impact of deposition temperature and precursor solution concentration on anode morphology, particle size and porosity. The electrochemical performance of the anode was measured by electrochemical impedance spectroscopy (EIS) using a Ni-CGO/YSZ/Ni-CGO symmetrical cell. The deposited anode had a particle size and porosity in ranging between 1.5-17 μm and 21%-52%, respectively. The estimated volume-specific triple phase boundary (TPB) length increased from 1.37 × 10⁻³ μm μm⁻³ to 1.77 × 10⁻¹ μm μm⁻³as a result of decrease of the particle size and increase of the porosity. The corresponding area specific charge transfer resistance decreased from 5.45 ohm cm² to 0.61 ohm cm² and the activation energy decreased from 1.06 eV to 0.86 eV as the TPB length increased.     

Efficient tuning of the Pt nano-particle mono-dispersion on Vulcan XC-72R by selective pre-treatment and electrochemical evaluation of hydrogen oxidation and oxygen reduction reactions

The effect of chemical pre-treatment of the carbon support used for deposition of Pt nano-particles is reported. Data on particle size, distribution and their electocatalytic activity toward hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) are reported. Vulcan XC-72R carbon was pre-treated with 5% HNO₃, 0.07 M H₃PO₄, 0.2 M KOH and 10% H₂O₂. The properties of carbon supports were studied by N₂ adsorption and X-ray photoelectron spectroscopy (XPS). Chemical reduction with ethylene glycol (EG) was used to synthesize Pt on carbon supports and the differences in catalyst morphology were characterized using CO chemisorption, X-ray diffraction, energy dispersive X-ray analysis and transmission electron microscope techniques. The electrocatalytic activity of Pt/C catalysts toward HOR and ORR was examined by cyclic voltammetry (CV) on a rotating ring-disk electrode (RRDE) and compared with E-Tek Pt/C. The ORR was predominantly involved via four-electron process with the first electron transfer being the rate-determining step. However, the specific activity and mass activity were greatly influenced by the pre-treatment employed.