A statistical physics approach to hydrogen sorption-desorption isotherms in LaNi4.3Fe0.7

Abstract

This study explores experimental hydrogen sorption and desorption isotherms on LaNi4.3Fe0.7 at four temperatures, employing different statistical physics models based on the grand canonical ensemble. The choice of the most appropriate model considered statistical parameters and physical analysis of the estimated parameters, culminating in selecting the monolayer model with two types of energies. The detailed analysis of these parameters provides an improved understanding of the process, highlighting the presence of hysteresis in the H2sorption and desorption in the metallic alloy. The sorption and desorption energies determined for this model vary between 82 and 109 kJmol−1, indicating a predominant chemical mechanism. Calculations of thermodynamic potentials suggest that the processes are exothermic and spontaneous. When comparing with other alloys of the same base, we observed that adding Fe presents similar trends in the model parameters, contributing to subtle improvements in the process.