Hydrogen sorption by porous materials composed of one to three elements selected from boron, carbon and nitrogen and metal modification to enhance the sorption

In order to develop novel hydrogen storage materials with high hydrogen capacity, layered compounds with high specific surface areas and large pore volumes, referred to as BN's, CN's and C's, were synthesized from B-, C- and/or N-containing substances through specified wet processing and optimized calcinations. Hydrogen contents at 77 K under 0.8 MPa of hydrogen increased as specific surface areas increased independently of the formulations of the samples, and almost all of them exceeded the predicted values for two dimensional condensation of hydrogen, that is, 2.34 mass% per 1000 m2 g−1. While modification with Pd did not increase the hydrogen capacity, Pt-modification brought about substantially higher hydrogen capacity at 77 K. Ni-modification also imparted higher hydrogen capacity to C's prepared by calcination of electrospun polyacrylonitrile fibers, but formation of mesopores on destroying micropores through excessive modification would reduce the hydrogen capacity.