Decoding Hydrogen Desorption Kinetics in Porous Silicon: An Electrical Circuit Modeling Approach

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Solid-state hydrogen storage offers enhanced safety and on-board application potential compared to conventional methods.
• Porous silicon (PS) is a promising nanostructure for hydrogen storage due to its high surface area and numerous hydrogenation sites.
• While hydrogen storage in PS is well-researched, thermal desorption characteristics remain underexplored.

Purpose of the Study:

• To investigate and analyze the thermal desorption of hydrogen from a hydrogen-terminated porous silicon surface.
• To optimize desorption temperature for efficient hydrogen release using spectroscopic analysis.
• To understand the kinetics and mechanisms governing hydrogen desorption from porous silicon.

Main Methods:

• Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) to monitor Si-H bonds during desorption.
• Analysis of relative peak intensities to quantify hydrogen retention (γ) and desorption kinetics.
• First-order reaction kinetic fitting to determine time constants and activation energies.

Main Results:

• Desorption curves were characterized by an excitation zone and a recombination zone, separated by a recombination threshold.
• The recombination zone exhibited an avalanche subzone (rapid desorption) and a saturation subzone (minimal desorption).
• Identified a critical operating point of 100 °C and 4 min, with an optimized desorption temperature of 250 °C.

Conclusions:

• The study provides a detailed analysis of thermal hydrogen desorption kinetics in porous silicon.
• Optimized desorption parameters are crucial for efficient hydrogen release in solid-state storage systems.
• An analogy to electrical capacitor discharge circuits was proposed for simplified analysis of desorption processes.