A novel study of the kinetics of external hierarchical nanostructures in methanol fuel cell

[摘要] For the purpose of a direct methanol fuel cell (DMFC), this research investigates the kinetics of methanol oxidation in a porous layer consisting of external hierarchical nanostructures through 2D COMSOL simulation. Three different lengths of nanowires (L) were considered in simulations. The investigation showed that specific activity was reversely proportional to nanowires length and roughness factor (Rf). However, the current density increased by increasing Rf. Although the current density in case of L = 200 nm and 500 nm was identical with respect to Rf, there was a slight deviation when L = 1000 nm due to the changing from kinetic to diffusion controlled regime, which was identified by investigation of Thiele modulus. The catalytic efficiency for L = 1000 nm dropped to 50% at Rf = 140, whereas the high efficiency with no mass-transport limitation was achieved by shorter nanowires. Therefore, increasing Rf within the simulation range resulted in increasing the total catalytic activity but simultaneously decreasing the specific activity because of the decrease in pore accessibility and catalytic efficiency of nanostructures.

[发布机构] Freiburg Materials Research Center, FMF, University of Freiburg, Germany^1;Department of Microsystems Engineering, IMTEK, University of Freiburg, Germany^2

[效力级别] 能源学

[关键词] Catalytic efficiencies;Diffusion-controlled regime;Hierarchical Nanostructures;High-efficiency;Kinetics of methanol oxidation;Mass transport limitation;Roughness factor;Specific activity