Hydrogen storage in Ti-Zr and Ti-Hf-based quasicrystals

The depletion of the world's petroleum reserves and the increased environmental impact of conventional combustion-engine-powered automobiles are leading to renewed interest in hydrogen storage materials. In the mid 1990s, Ti/Zr/Hf-based quasicrystals were demonstrated to store more hydrogen than competing crystal intermetallic phases. Unfortunately, recovery of the hydrogen required temperatures in excess of 400°C, severely limiting the technological application of these materials. Here, the Ti/Zr-Hf-based quasicrystals and crystal approximants are reviewed and their hydrogenation properties are discussed. We also report the discovery of a relatively flat pressure plateau for hydrogenated TiZrNi quasicrystals at modest pressures (100-200psi) that extends to hydrogen concentrations in excess of 4 wt.%. Approximately 2wt.% of the hydrogen is easily recovered by heating at temperatures as low as 200°C.