1. Palladium, a hydrogen sponge

Many see hydrogen (H ₂ ) as the energy source that will replace fossil fuels in the future. Fuel cells and direct combustion engines use hydrogen and have the enormous advantage of releasing only one totally harmless waste product into the environment: water. The downside is that the risk of explosion above 4% hydrogen gas in air is high, raising real safety issues that could prove prohibitive to the development of consumer applications.

To date, the devices widely used in the oil industry to detect and measure hydrogen content are too complex, too slow and too expensive to be considered for integration in a hydrogen-powered car. Performance in terms of reliability, size, safety of use, power consumption and manufacturing costs needs to be improved, both for leak detection and for...