Cathode activity plays an important role in the improvement of the microbial fuel cells on ocean floor （BMFCs）. A comparison study between Rayon-based （CF-R） and PAN-based carbon fiber （CF-P） cathodes is conduct...Cathode activity plays an important role in the improvement of the microbial fuel cells on ocean floor （BMFCs）. A comparison study between Rayon-based （CF-R） and PAN-based carbon fiber （CF-P） cathodes is conducted in the paper. The two carbon fibers were heat treated to improve cell performance （CF-R-H ＆ CF-P-H）, and were used to build a new BMFCs structure with a foamy carbon anode. The maximum power density was 112.4mWm-2 for CF-R-H, followed by 66.6mWm-2 for CF-R, 49.7 mWm-2 for CF-P-H and 21.6mWm-2 for CF-P respectively. The higher specific area and deep groove make CF-R have a better power output than with CF-P. Meanwhile, heat treatment of carbon fiber can improve cell power, nearly two-fold higher than heat treatment of plain fiber. This improvement may be due to the quinones group formation to accelerate the reduction of oxygen and electron transfer on the fiber surface in the three phase boundary after heat treatment. Compared to PAN-based carbon fiber, Rayon-based carbon fiber would be preferentially selected as cathode in novel BMFCs design due to its high surface area, low cost and higher power. The comparison research is significant for cathode material selection and cell design.展开更多
The elastic stress fields caused by a dislocation in GexSil~ epitaxial layer on Si substrate are investigated in this work. Based on the previous results in an anisotropic bimaterial system, the image method is furthe...The elastic stress fields caused by a dislocation in GexSil~ epitaxial layer on Si substrate are investigated in this work. Based on the previous results in an anisotropic bimaterial system, the image method is further developed to determine the stress field of a dislocation in the film-substrate system under coupled condition. The film-substrate system is firstly transformed into a bimaterial system by distributing image dislocation densities on the position of the free surface. Then, the unknown image dis- location densities are solved by using boundary conditions, i.e., traction free conditions on the free surface. Numerical simula- tion focuses on the Ge0.1Si0.9/Si film-substrate system. The effects of layer thickness, position of the dislocation and crystallo- graphic orientation on the stress fields are discussed. Results reveal that both the stresses σxx,σxz at the free surface and the stress o-σx, σyy, σyz on the interface are influenced by the layer thickness, but the former is stronger. In contrast to the weak de- pendence of stress field on the crystallographic orientation the stress field was strongly affected by dislocation position. The stress fields both in the film-substrate system and bimaterial system are plotted.展开更多
基金support by the Key Project of Nature Science Fund of Shandong Province, China (ZR2011B Z008)the Special Fund of Marine Renewable Energy from China’s State Oceanic Administration (GHME 2011GD04)
文摘Cathode activity plays an important role in the improvement of the microbial fuel cells on ocean floor （BMFCs）. A comparison study between Rayon-based （CF-R） and PAN-based carbon fiber （CF-P） cathodes is conducted in the paper. The two carbon fibers were heat treated to improve cell performance （CF-R-H ＆ CF-P-H）, and were used to build a new BMFCs structure with a foamy carbon anode. The maximum power density was 112.4mWm-2 for CF-R-H, followed by 66.6mWm-2 for CF-R, 49.7 mWm-2 for CF-P-H and 21.6mWm-2 for CF-P respectively. The higher specific area and deep groove make CF-R have a better power output than with CF-P. Meanwhile, heat treatment of carbon fiber can improve cell power, nearly two-fold higher than heat treatment of plain fiber. This improvement may be due to the quinones group formation to accelerate the reduction of oxygen and electron transfer on the fiber surface in the three phase boundary after heat treatment. Compared to PAN-based carbon fiber, Rayon-based carbon fiber would be preferentially selected as cathode in novel BMFCs design due to its high surface area, low cost and higher power. The comparison research is significant for cathode material selection and cell design.
基金supported by the Science and Technology on Surface Physics and Chemistry Laboratory(Grant No.SPC201106)
文摘The elastic stress fields caused by a dislocation in GexSil~ epitaxial layer on Si substrate are investigated in this work. Based on the previous results in an anisotropic bimaterial system, the image method is further developed to determine the stress field of a dislocation in the film-substrate system under coupled condition. The film-substrate system is firstly transformed into a bimaterial system by distributing image dislocation densities on the position of the free surface. Then, the unknown image dis- location densities are solved by using boundary conditions, i.e., traction free conditions on the free surface. Numerical simula- tion focuses on the Ge0.1Si0.9/Si film-substrate system. The effects of layer thickness, position of the dislocation and crystallo- graphic orientation on the stress fields are discussed. Results reveal that both the stresses σxx,σxz at the free surface and the stress o-σx, σyy, σyz on the interface are influenced by the layer thickness, but the former is stronger. In contrast to the weak de- pendence of stress field on the crystallographic orientation the stress field was strongly affected by dislocation position. The stress fields both in the film-substrate system and bimaterial system are plotted.
