Passivity degradation of Alloy 800 in simulated crevice chemistries was systematically investigated using cyclic polarization curve, electrochemical impedance spectroscopy(EIS), Mott-Schottky analysis, Auger electron ...Passivity degradation of Alloy 800 in simulated crevice chemistries was systematically investigated using cyclic polarization curve, electrochemical impedance spectroscopy(EIS), Mott-Schottky analysis, Auger electron spectroscopy(AES)and atomic absorption spectrometry(AAS). Cyclic polarization showed that the pitting potential in a thiosulfate solution was much lower than in either a chloride solution or a sulfate-chloride solution. Mott-Schottky results revealed that passive films showed n-type semiconductivity, and the presence of thiosulfate in chloride solution led to an increased donor density in the passive film. EIS spectra indicated that thiosulfate enhanced the film dissolution rate in chloride solutions. Moreover, thiosulfate enhanced the pitting propagation rate in chloride solution by stabilizing the metastable pits and forming sulfide within the pits.展开更多
A solid state H2S/air electrochemical cell having the configuration of H2S, (MoS2+NiS+Ag)/YSZ/Pt, air has been examined with different H2S flow rates and concentrations at atmospheric pressure and 750-850 ℃. Performa...A solid state H2S/air electrochemical cell having the configuration of H2S, (MoS2+NiS+Ag)/YSZ/Pt, air has been examined with different H2S flow rates and concentrations at atmospheric pressure and 750-850 ℃. Performance of the fuel cell was dependent on anode compartment H2S flow rate and concentration. The cell open-circuit voltage increased with increasing H2S flow rate. It was found that increasing both H2S flow rate and H2S concentration improved current-voltage and power density performance. This is resulted from improved gas diffusion in anode and increased concentration of anodic electroactive species. Operation at elevated H2S concentration improved the cell performance at a given gas flow rate. However, as low as 5% H2S in gas mixture can also be utilized as fuel feed to cells. Highest current and power densities, 17500mA·cm-2 and 200mW·cm-2, are obtained with pure H2S flow rate of 50ml·min-1 and air flow rate of 100ml·min-1 at 850℃.展开更多
A positive-electrolyte-negative(PEN)assembly solid oxide fuel cell(SOFC)with a thin electrolyte film for intermediate temperature operation was fabricated.Instead of the traditional screen-printing method,both anode a...A positive-electrolyte-negative(PEN)assembly solid oxide fuel cell(SOFC)with a thin electrolyte film for intermediate temperature operation was fabricated.Instead of the traditional screen-printing method,both anode and cathode catalysts were pressed simultaneously and formed with the fabrication of nano-composite electrolyte by press method.This design offered some advantageous configura-tions that diminished ohmic resistance between electrolyte and electrodes.It also increased the proton-conducting rate and improved the performance of SOFCs due to the reduction of membrane thickness and good contact between electrolyte and electrodes.The fabricated PEN cell generated electricity between 600℃ and 680℃ using H2S as fuel feed and air as oxidant.Maximum power densities 40 mW·cm^(-2) and 130 mW·cm^(-2) for the PEN configuration with a Mo-Ni-S-based composite anode,nano-composite electrolyte(Li_(2)SO_(4)+Al_(2)O_(3))film and a NiO-based composite cathode were achieved at 600℃ and 680℃,respectively.展开更多
基金Supported by the Atomic Energy of Canada Limited(AECL)and National Natural Science Foundation of China(No.51371124)
文摘Passivity degradation of Alloy 800 in simulated crevice chemistries was systematically investigated using cyclic polarization curve, electrochemical impedance spectroscopy(EIS), Mott-Schottky analysis, Auger electron spectroscopy(AES)and atomic absorption spectrometry(AAS). Cyclic polarization showed that the pitting potential in a thiosulfate solution was much lower than in either a chloride solution or a sulfate-chloride solution. Mott-Schottky results revealed that passive films showed n-type semiconductivity, and the presence of thiosulfate in chloride solution led to an increased donor density in the passive film. EIS spectra indicated that thiosulfate enhanced the film dissolution rate in chloride solutions. Moreover, thiosulfate enhanced the pitting propagation rate in chloride solution by stabilizing the metastable pits and forming sulfide within the pits.
基金Supported by the Natural Science Foundation of Guangdong Province (No. 031424).
文摘A solid state H2S/air electrochemical cell having the configuration of H2S, (MoS2+NiS+Ag)/YSZ/Pt, air has been examined with different H2S flow rates and concentrations at atmospheric pressure and 750-850 ℃. Performance of the fuel cell was dependent on anode compartment H2S flow rate and concentration. The cell open-circuit voltage increased with increasing H2S flow rate. It was found that increasing both H2S flow rate and H2S concentration improved current-voltage and power density performance. This is resulted from improved gas diffusion in anode and increased concentration of anodic electroactive species. Operation at elevated H2S concentration improved the cell performance at a given gas flow rate. However, as low as 5% H2S in gas mixture can also be utilized as fuel feed to cells. Highest current and power densities, 17500mA·cm-2 and 200mW·cm-2, are obtained with pure H2S flow rate of 50ml·min-1 and air flow rate of 100ml·min-1 at 850℃.
基金supported by the Natural Science Foundation of Guangdong Province(No.05006552).
文摘A positive-electrolyte-negative(PEN)assembly solid oxide fuel cell(SOFC)with a thin electrolyte film for intermediate temperature operation was fabricated.Instead of the traditional screen-printing method,both anode and cathode catalysts were pressed simultaneously and formed with the fabrication of nano-composite electrolyte by press method.This design offered some advantageous configura-tions that diminished ohmic resistance between electrolyte and electrodes.It also increased the proton-conducting rate and improved the performance of SOFCs due to the reduction of membrane thickness and good contact between electrolyte and electrodes.The fabricated PEN cell generated electricity between 600℃ and 680℃ using H2S as fuel feed and air as oxidant.Maximum power densities 40 mW·cm^(-2) and 130 mW·cm^(-2) for the PEN configuration with a Mo-Ni-S-based composite anode,nano-composite electrolyte(Li_(2)SO_(4)+Al_(2)O_(3))film and a NiO-based composite cathode were achieved at 600℃ and 680℃,respectively.
