Research Article Hydrogenated Microstructure and Its Hydrogenation Properties: A Density Functional Theory Study M. Abdus Salam, Bawadi Abdullah, and Suriati Sufian Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan, Malaysia Correspondence should be addressed to Bawadi Abdullah; bawadi abdullah@petronas.com.my Received 24 June 2014; Revised 12 August 2014; Accepted 12 August 2014; Published 13 October 2014 Academic Editor: Fathallah Karimzadeh Copyright © 2014 M. Abdus Salam et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. he relationship between microstructure and hydrogenation properties of the mixed metals has been investigated via diferent spectroscopic techniques and the density functional theory (DFT). FESEM and TEM analyses demonstrated the nano-grains of Mg 2 NiH 4 and MgH 2 on the hydrogenated microstructure of the adsorbents that were conirmed by using XPS analysis technique. SAED pattern of hydrogenated metals attributed the polycrystalline nature of mixed metals and ensured the hydrogenation to Mg 2 NiH 4 and MgH 2 compounds. Flower-like rough surface of mixed metals showed high hydrogenation capacity. he density functional theory (DFT) predicted hydrogenation properties; enthalpy and entropy changes of hydrogenated microstructure of MgH 2 and Mg 2 NiH 4 are −62.90 kJ/mol, −158 J/mol⋅K and −52.78 kJ/mol, −166 J/mol⋅K, respectively. he investigation corresponds to the hydrogen adsorption feasibility, reversible range hydrogenation thermodynamics, and hydrogen desorption energy of 54.72 kJ/mol. DFT predicted IR band for MgH 2 and Mg 2 NiH 4 attributed hydrogen saturation on metal surfaces. 1. Introduction he global energy demand is increasing in parallel with the population growth, economic expansion, and increasing demand of mobility. Hydrogen is known as an abundant source of clean energy carrier. here are few ways to utilize the hydrogen as source of energy. Metal-hydrogen system demonstrated the best option for hydrogenated system due to the higher hydrogen density in the system than liquid or gas phases [1]. Higher hydrogen density, reversible thermody- namics, low desorption temperature, and low production cost are vital requirements for metal-hydrogen system. Magne- sium based mixed oxides are potential candidate to meet the above requirements [2]. he drawbacks of hydrogenation in magnesium based alloys are [3] stability of the MgH 2 phase, formation of a surface oxide(s), slow dissociation of hydrogen at the metal surface, and slow difusion of hydrogen through MgH 2 grain. he problems can be overcome by developing microstructure that reduces the difusion path and creates enough active site for dissociation [2, 3]. Grain boundaries provide active nucleation sites in hydride formation and decomposition of the hydride phases. Reduction of grain size or crystalline size of the materials enhances the hydrogen difusion that moves faster along the grain boundaries. Diferent strategies have been investigated to achieve reversible range hydrogen adsorption thermodynamics and kinetics. Homogenous and ultraine microstructure of adsor- bent is one of the important techniques to enhance the hydro- genation capacity and to achieve favorable thermodynamics [4]. Second technique is considered as addition of catalytic elements or rear earth metals or transitional metals to adsorbent. Transition metal oxides are an important catalyst in Mg-based adsorbent to get high hydrogenation capacity [5]. Mg 2 Ni alloy demonstrates higher hydrogenation kinetics and desorption at lower temperature because of the efect of transitional metal such as nickel [6]. Coprecipitation under low supersaturation synthesis method produces homoge- nously metals dispersed hydrotalcite [7]. he materials show high catalytic activity for hydrogenation and lexible to form diferent microstructure by optimizing the preparation conditions and metals. Hindawi Publishing Corporation Journal of Nanomaterials Volume 2014, Article ID 749804, 7 pages http://dx.doi.org/10.1155/2014/749804