Mechanistic investigation of hydrogen generation from water and magnesium catalyst reaction: Advanced reactive molecular dynamics simulation

Abstract

Magnesium is an effective catalyst for producing hydrogen through thermochemical water splitting. However, the slow reaction between Mg and water prevents this catalyst from being commercially useful. In this study, reactive MD simulations with accurate force fields and reactive potential energy surfaces are used to comprehend the slow-kinetics of the Mg-water reaction. At room temperature, water is split when it interacts with Mg nanoparticles and forms a Mg–H bond. Furthermore, at temperatures above 1200 K, Mg–H bonds begin to dissociate, resulting in the generation of hydrogen radicals from the Mg–H bond. The percentage of H–H bonds is almost zero until the reaction pathway reaches temperature 2000K, after which H radicals combine to form hydrogen gas. The analysis of temperature dependent data reveals that oxygen and hydrogen atoms combine with Mg elements to form massive stable linear and branched chains, resulting in slow Mg-water reaction kinetics for hydrogen production. Therefore, current studies utilizing reactive molecular dynamics can provide a means of improving the kinetics of the Mg-water reaction.