Hierarchical Bulk Nanoporous Aluminum for on-Board Hydrogen and Heat Generation By Hydrolysis in Pure Water

Abstract

Despite the remarkable key features of hydrogen energy technology such as the high gravimetric energy density of hydrogen, the zero-emissions electricity generated using fuel cells, and the high natural abundance of hydrogen resources (particularly in the form of water), there are still many scientific and engineering challenges that must be addressed before a true sustainable hydrogen economy can be realized. Two of these challenges include sustainable hydrogen generation without CO2 emissions and effective storage of this hydrogen for specific applications. In this presentation, I will present a sustainable method to produce hydrogen on-board, which could be used to overcome the two challenges mentioned above. Our approach involves: (i) Fabrication by selective alloy corrosion of hierarchical bulk nanoporous aluminum characterized by the coexistence of both macroscopic and mesoscopic ligament/pore structures, with the mesoscopic ligaments in the range of 10-20 nm. (ii) Recovery of the sacrificial material simultaneously during selective alloy corrosion, which contributes to sustainability of the process. (iii) Use of this hierarchical bulk nanoporous aluminum to produce hydrogen and heat on-board by hydrolysis with “pure” water, with a yield of ~52-85 % during hydrogen production without incorporation of any catalyst or reaction promoter in the aluminum-water system. Besides hydrogen and heat generations, I will demonstrate the combustion of this bulk nanoporous aluminum in air and under ambient conditions, which implies that this material could be attractive as a combustion fuel catalyst, e.g. to enhance the ignition and combustion of solid propellants. Thanks to a new carbon-free sustainable pathway to extract aluminum by Elysis (https://elysis.com/en), a joint venture composed of high-profile aluminum suppliers including Rio Tinto and Alcoa, and aluminum consumers including Apple, aluminum can be obtained by electrolysis of Al2O3 without CO2 emissions. The inclusion of this carbon-free aluminum in our process will make it possible to produce hydrogen from nanoporous aluminum and pure water without greenhouse gas emissions at any stage of the process.