Sorption Properties of Ball-Milled Porous Silicon for Hydrogen Storage Upto 80 Bar

Abstract

Hydrogen is emerging as a potential energy carrier candidate for cost-effective, clean, and sustainable practices, ultimately contributing towards economic security. Though solid-state hydrogen storage using metal and complex hydride is an attractive storage solution, it operates at high temperatures (>400 ℃) and exhibits slow reaction kinetics. Due to high surface energy and hydrogen affinity, using porous materials (e.g., carbon nanostructures, MOFs, zeolites, and porous polymers) is an alternative approach. However, cryogenic temperature operation and insignificant storage at ambient conditions (due to poor surface coverage) are major demerits of these porous materials. This work proposes an intermediate solution to use Ball-milled Porous Silicon (BMPS) and is focused on studying its structure and physical characteristics during pre- and post-hydrogenation. BMPS surpasses the US DOE target to achieve a storage capacity of 10.7 wt.% at 80 bar and 120 °C. XPS studies the surface states and Si hydride bonding. The effect of nanostructuring on decomposition energy is observed by differential scanning calorimetry. Reduced particle and crystallite size, analyzed by XRD and Raman spectroscopy, expose nano-pores to hydrogen. The exposure improves storage capacity in both free and surface-attached forms, making BMPS attractive for reversible storage applications