Improved Open Circuit Voltage in Nano-Porous Silicon Based Hydrogen Fuel Cell

Abstract

Hydrogen fuel cell generates electrical energy from the electrochemical reaction of hydrogen and oxygen with water vapor as a by-product. Polymer Exchange Membrane Fuel Cell (PEMFC) and Direct Methanol Fuel Cell (DMFC) which are normally utilized for portable applications are not only costly due to platinum electrodes, polymer membrane and supply of hydrogen or methanol as a fuel but also not integrable with silicon fabrication technology. Novel fuel cell based on nanoporous silicon (PS) as Metal/nanoPS/silicon Schottky type structure is under development and Open Circuit Voltage (Voc) upto 550 mV with Au as anode catalyst has been reported. Such fuel cell uses nanoporous silicon layer as proton exchange membrane. This type of structure is found to show humidity-voltaic effect i.e. generation of voltage in humid ambient. Humidity-stimulated voltage generation is facilitated by the hydrogen component of water present in the atmosphere. In the present work, our main objective was to improve Voc. We achieved Voc upto 1.118 V by restricting the pore size of nanoporous silicon to 4-5 nm and thickness of the Cu film to 100 nm. These results suggest that this type of fuel cell could be utilized to develop self-powered integrated circuit.