Optimization of Thermal Desorption from Hydrogenated Porous Silicon

Abstract

The hydrogen desorption from widely studied metal hydrides requires high temperatures (> 400 ℃), a significant bottle-neck for cyclic storage. Despite the advantage of porous materials with large surface areas, hydrogen desorption from the adsorbed surface is rarely reported. The work investigates and analyzes the thermal desorption of hydrogen-terminated porous silicon (PS) surface using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) to optimize the temperature for efficient desorption, as the FTIR is sensitive to identify the presence of Si hydride species. The relative peak intensities in the spectra estimate the relative hydride (Si-Hx) terminations for desorption rates. The work suggests a hydrogen desorption mechanism explaining the temperature effect. The analysis designates 100 °C as the critical temperature for the desorption, whereas 250 °C is the optimized temperature for efficient desorption from PS. The desorption temperature optimization may facilitate the use of PS for cyclic hydrogen storage onboard applications.