They had many challenges to overcome in order for the process to be a viable, affordable option, the least of which was the oxidation film that forms on aluminum. This allows aluminum to easily be used for things like soda (or pop, if you prefer) cans, but makes it more difficult to use as an efficient hydrogen generator in a fuel cell.^4,5  The scientists tackled the oxidation problem using gallium, which can melt in your hands given its relatively low melting point,⁶ preventing the need for very high temperatures in order for the production of hydrogen to occur. With the oxidation and temperature issues under control, they next turned their efforts to recovering the expensive gallium by investigating various salts, including sodium chloride,^3,6,7 to encapsulate and allow for reuse of the gallium.⁶ At this point, you would think the world would be rejoicing, the only problem was that the salt necessary to reuse the gallium slowed down the reaction.

All was not lost however, Aly Kombargi, a Ph.D. candidate at Massachusetts Institute of Technology, and his team found that the reaction just needed a jolt, of caffeine that was, or more specifically, imidazole, a key component of caffeine.^4,5  Who would have thought that the drug that wakes you up could also speed up the reaction between the water and the aluminum to make hydrogen generation a much quicker process? What previously took approximately 2 hours could now happen in about 10 minutes.^4,5 With this last puzzle piece, we have the ideal viable and affordable hydrogen-generation process that is quick, can be performed at low temperature, allows for the reuse of the expensive materials and recycling of the cheaper ones, and has easy-to-obtain main ingredients (i.e., salt water and aluminum). With the various improvements to the reaction since 2009, the hydrogen yield has increased from 78%³ to > 95%⁶ to near 100%^4,5, with zero carbon dioxide emissions,⁶ indicating that hydrogen fuel cells might be more practical than previously thought.^4,5 Kombargi is even using used aluminum cans^4,5 indicating there is the potential for better aluminum recycling options as well.