STTR Phase I: Hydrogen Storage in Catalytically-modified Porous Silicon

This STTR Phase I project will study the storage of hydrogen on a novel material produced from silicon - the same substance used to make solar panels and computer chips. This unique and patented approach has the potential to eclipse all prior methods of hydrogen storage in terms of pressure, temperature, safety, cost, and convenience. Silicon is earth-abundant and benign to humans - it is even promotes healthy skin, hair, and fingernails. The implication of hydrogen-in-silicon is that fuel cell-powered vehicles, homes, and electronics can be far more efficient and clean than any other source of energy. Of great significance is that this technology will allow homeowners and businesses to generate their own hydrogen by splitting water using rooftop solar panels. By storing this as hydrogen-in-silicon a home can be run overnight or for many days during a cloudy spell. Hydrogen can replace the batteries in portable electronics so they can last up to 20 days without a recharge - far longer than with batteries. And if the rooftop system is of sufficient size, one can produce the hydrogen needed for a fuel cell vehicle, such as those already on the market. The implications of this are far-reaching, allowing complete energy independence for all, for all time to come, with minimal environmental impact and using almost completely renewable and low-cost resources which are easy to recycle. Porous silicon is easy to synthesize but requires a catalyst to recharge from a gaseous source. The introduction of the catalyst is critical as it must be controlled spatially and positioned to effect spillover onto and off of silicon. Density Functional Theory studies show this is energetically favorable and first-order macroscopic calculations indicate that recharge can be effected in 3.5 minutes at 8 bar and 250 C. The overall energy difference between fully-charged and fully-discharged silicon-hydrogen is an amazingly low 1 kcal/mol. The energy barrier is the strong H-H bond which dominates the kinetics. The course of this project is to strategically place palladium atoms at specific sites on the matrix of porous silicon so that it can mediate the H-H bond energy and allow spillover onto the 800 m^2/gm surface area of microporous silicon. This has been patented but never demonstrated in the laboratory, which is why this funding from NSF is needed. A further goal of this work is to demonstrate the viability of low-cost silicon using metallurgical grade material instead of the single-crystal silicon which has been used to date.