Correlating porosity with water-quality tolerance for practical on-demand hydrogen generation using porous silicon

Moving away from fossil fuels demands practical methods to generate hydrogen (H 2 ) when needed. While large-scale H 2 production technologies continue to advance, portable and field-deployable systems remain underdeveloped. Porous silicon (p-Si), which generates H 2 when reacting with alkaline water, offers a promising route; however, the effect of its physical structure on performance under realistic conditions remains poorly understood. This study systematically examines p-Si materials synthesized via magnesiothermic reduction at varying heating rates to link crystallinity, surface area, and pore size with H 2 generation efficiency across diverse natural water sources (ocean, river, lake, well, and rainwater). The results reveal that p-Si with pore sizes below 10 nm and surface areas above 100 m 2 g −1 are critical for sustaining high H 2 yields at a fast rate, in impure water sources. These findings establish a clear structure–property relationship that advances the design of robust, on-demand chemical H 2 storage materials for real-world applications. • Water quality can adversely affect the performance of H 2 production with porous silicon. • Adjusting the physical properties of porous silicon enhances its tolerance to impure water. • For high performance in non-pure water sources, porous silicon requires pores smaller than 10 nm. • This finding enhances the practical use of porous silicon for real-world H 2 storage.