Mechanism of Silver Nanoparticles Deposition by Electrolysis and Electroless Methods on a Graphite Substrate

This study shows a silver electrodeposition model (EDM) on a graphite ‎substrate. The electrolyte was a 0.01 M solution of pure silver and chromium nitrate using an ‎electrolyzing cell. EDC with current density up to 20 mA/cm2 and 15 mV and pulse current were studied. Results revealed that silver deposited at a ‎rate of 0.515 mg/cm2/min with 12 mA /cm2 that decreases to 0.21 and 0.16 mg/cm2.min ‎with the decrease of current density to 6 and 5 mA/cm2 respectively. The model postulates that ‎silver ions (a) were first hydrated before diffusing (b) from the solution bulk to ‎the cathode vicinity, the next step (c) involved the chemical adsorption of these ions on certain ‎accessible sites of the graphite substrate (anode), the discharged entities (d) adhere to the graphite ‎surface by Van der Vales force. Silver ions are deposited because the ‎discharge potential of silver is low (0.38 mV) as compared to other metal ions like chromium (0.82 mV). Pulse ‎current controls silver deposition due to flexibility in controlling steps (a) - (c) of the ‎deposition mechanisms.

Degradation of Metal-Supported SOFC and One Powerful Investigation Method: Multi-Scale Modeling and Simulation

Metal-supported solid oxide fuel cell (SOFC) has a varieties of potential advantages compared to the traditional ceramic supported SOFC. However, degradation issue of metal-supported SOFC is seriously impeding its further development, in particular, the inter-diffusion and interaction of iron, chromium and nickel at substrate/anode interface is known to be a key issue responsible for cell rapid degradation. With respect to the complexity and nonlinearity of degradation mechanism, multi-scale modeling and simulation is regarded as one powerful method to gain a deep insight on degradation mechanism. In present work, multi-scale models were presented to investigate multi-scale physicochemical phenomena happening at interface of anode/substrate, with the attempt to reveal degradation mechanism. The research procedure for the above goal was addressed in detail as well.

Electrochemical Treatment of Wastewater Containing Chlorophenols Using Boron-Doped Diamond Film Electrodes

The electrochemical treatment of wastewater containing 2, 4, 6-trichlorophenol has been carried out experimentally with synthetic boron-doped diamond (BDD) thin film electrodes. Removal rate of COD, instant current efficiency (ICE) and energy consumption were investigated under different current density. The influence of supporting media is reported, which plays an important role in determining the global oxidation rate. The oxidative chloride is stronger than peroxodisulphate. The electrochemical characteristics of boron-doped diamond electrodes were investigated in comparison with active coating Ti substrate anode (ACT). The experimental results show that BDD is markedly superior to ACT due to its different absorption properties.

Effect of Processing Conditions on Curvature of Anode/Electrolyte SOFC Half-Cells Fabricated by Electrophoretic Deposition

Thin-electrolyte anode-supported solid oxide fuel cells (YSZ/NiO–YSZ) were fabricated for intermediate-temperature operation using electrophoretic deposition (EPD). During cosintering, the half-cells were observed to warp—an undesirable characteristic—due to mismatch in the sintering rates. The influence of the temperature for anode presintering—a key processing step—on the curvature of the half-cells induced by sintering was investigated over 700–1400°C. It was found that the maximum curvature occurred for an anode presintered at 900°C, while the minimum was observed at 1200°C. Anode presintering temperature was also found to affect the rate of electrophoretic deposition. At low presintering temperatures, the rate of EPD increased due to the enhancement in substrate (anode) electronic conductivity as a result of an increased percolating network of NiO. Further increases in presintering temperature, however, resulted in a decrease in the EPD rate due to the formation of a surface layer with poor electronic conductivity as a result of NiO diffusion from the NiO-YSZ anode to the sintering crucible.

Ceramic Technologies for Anode-Supported Solid Oxide Fuel Cells

One of the most promising technologies for future applications of solide oxide fuel cells (SOFC)is the so-called “anode-supported” configuration: a dense yttria-stabilised zirconia (YSZ) ceramic electrolyte is deposited as a thin film over a porous Ni / YSZ cermet substrate anode, followed by a porous ceramic cathode such as La1-xSrxMnO3 (LSM). In this paper, a short review is made of the current technologies available to achieve this particular architecture, and to optimise the service behaviour. Then, alternative materials and fabrication technologies, as well as their possible impact on performance, are proposed and investigated.