Silicon nanograss as micro fuel cell gas diffusion layer

This Letter describes a microfabricated fuel cell (MFC) that uses hydrogen as fuel and a polymer proton exchange membrane as electrolyte. Microchannels have been etched in highly conductive silicon, and silicon nanograss (black silicon) has been formed on the surface; thus implementing a support structure, current collector, flowfield and gas diffusion layer all in one. The devices are thus very compact, simple to fabricate and low cost. The MFC presented here shows promising performance of 70 mW cm^-2 power density and 100 mA cm^-2 current density at 0.7 V, comparable to that of other similar monolithic devices found in the literature.