Porous silicon as a proton exchange membrane for micro fuel cells

The porous silicon wafer filled with acid or Nafion was developed as a proton conduction membrane for micro fuel cells. The pores in size of 3 - 6 μm penetrated through the silicon wafer were prepared by anodic etching with back illumination. When the sulfuric solution or the Nafion solution sank the porous silicon substrate, it was assembled into the H₂ / air feed fuel cell test section at ambient conditions using conventional electrodes. For the porous wafer filled with sulfuric solution of 10% and 20%, the open circuit voltages (OCV) of 0.932 V and 0.971 V were obtained and the maximum power density of 12.75 mW/cm² was achieved. For the Nafion filled porous silicon wafer, an OCV of 0.892 V and a maximum power density of 1.27 mW/cm ² were achieved.