Fabrication of MEMS-based Micro Direct Methanol Fuel Cell Using Porous Silicon as Catalysts Substrates

Abstract

In order to further miniaturize the silicon-based micro direct methanol fuel cell (μDMFC), a novel method of fabricating MEMS-based single is μDMFC introduced. Using the silicon micromachining techniques, including thermal oxidation, optical lithography, wet etching, silicon anodization, physical vapor deposition, electroless plating, laser beams cauterization, and anodic bonding, we have successfully made single μDMFC as small as 10 mm×8 mm×3 mm. First a porous silicon (PS) layer used as single cells substrate is formed by anodic etching in a HF-ethanol solution which is considered an effective and cheap fabrication method. Differs from other researchers, the electrocatalysts layer is deposited by electroless plating platinum or platinum and ruthenium (Pt-Ru) co-deposition over PS substrates. Catalyst being deposited over PS brings three-dimensional features, and the non-planar interfaces for the catalytic electrodes will increase the active surface area within a stated volume. Additionally, as high as 95% the utilization ratio of noble metal in electroless plating solution leads economizing platinum and ruthenium. SEM, EDX are employed to analysis the PS and catalyst layer. Moreover, using the MEMS technology makes the batch fabrication of μDMFC much easier and can reduce the usage of rare metals.