Hierarchical Porous Carbon Arrays Derived from Directly Carbonizing Carex Meyeriana for Counter Electrodes of High-Efficiency Dye-Sensitized Solar Cells

Hierarchical porous carbon arrays (HPCAs) are facilely produced by directly carbonizing Carex meyeriana through a self-activated and self-template process. The morphology analysis and nitrogen sorption measurements reveal that the obtained HPCAs have a large specific surface area and unique hierarchical pore structure comprising macropore channel arrays and micropores and mesopores developed on the wall of macropore channels. The HPCA electrodes are subsequently prepared by depositing HPCAs to the fluorine-doped tin oxide conductive substrate. Electrochemical tests demonstrate that the HPCA electrode shows a superior electrocatalytic activity for the regeneration of the I-/I-3(-) electrolyte. The superior electrocatalytic activity of HPCA electrodes is mainly due to the combined effect of unique hierarchical pore architecture and large surface area, which facilitates the electrolyte diffusion and provides the abundant effective electrocatalytic active sites. Under 1 sun illumination, the HPCA electrode-based dye-sensitized solar cell displays a gratifying conversion efficiency of 6.45%, which is close to that based on commonly used Pt electrodes.