Hydrogen storage in hierarchical nanoporous silicon-carbon nanotube architectures

A porous silicon (pSi) wafer with a hierarchical, nanoporous architecture and pure single wall carbon nanotubes (SWNTs) have been combined by electrophoretic infiltration to form a unique hybrid pSi-SWNT hydrogen storage system. The pSi architecture was fabricated by anodic etching of silicon wafers in alcoholic solutions of hydrogen fluoride. Direct hydrogen dosing to adsorb hydrogen on the pSi-SWNT hybrid, pure pSi, electrochemically charged pSi and SWNTs, and pure SWNTs, followed by temperature programmed desorption measurements, were used to quantify the hydrogen adsorption process. The results indicate an increased hydrogen storage capacity at a lower temperature in the pSi-SWNT system relative to that from pure pSi, and pure and charged SWNTs. In addition, hydrogen adsorption in pSi-SWNT is about a factor of 2 to 6 higher than that in pure and charged pSi, and pure and charged SWNTs.