First Principles Investigation for H2 Dissociative Adsorption on Ni and Cr-Decorated Ni Surfaces - An Application to Alkaline Polymer Electrolyte Fuel Cell

Abstract

In this research, density functional theory (DFT) calculations for H2 dissociative adsorption on Ni(111) and Cr-decorated Ni surfaces are performed to compare and understand the adsorption mechanism on both surfaces as an application to alkaline polymer electrolyte fuel cell (APEFC). The Cr-decorated Ni (CrML/Ni(111)) surface is constructed by placing a monolayer of Cr atoms on the topmost layer of a Ni (111) surface. The potential energy scans for H2 dissociative adsorption on both surfaces reveal that the activation barrier of Cr-decorated Ni surface is lower than that of the pristine Ni surface. For both surfaces, the H atoms are dissociated with a distance of 1.8Å; but H2 on Cr-decorated Ni surface has greater adsorption energy than for H2 on Ni(111) surface. The density of states (DOS) shows that the presence of Cr increased the unoccupied states in the region around the Fermi level as compared to clean Ni surface. The increase in unoccupied states is supported by the computed total charges of the atoms before and after the Cr monolayer is added on the Ni surface which also implies a strong metal-to-metal interaction between Ni and Cr atoms. The difference in the charges of the H atoms and the surface atoms before and after the adsorption on the surfaces shows an easier transfer of charges between H atoms and surface atoms of Cr-decorated Ni surface than the surface atoms of Ni surface.

Hydrogen atom absorption in hydrogen-covered Pd(110) (1 × 2) missing-row surface

“…The interaction of H with metal surfaces is a fundamental process in the field of surface science that is often used as standard to understand the catalytic reactivity of metals and to observe or establish relevant scientific concepts. Studies related to this system are continuously conducted due to the central role of hydrogen in the realization of clean and efficient energy source [1][2][3][4]. Specifically, the absorption of H atoms in subsurface and bulk regions is an important process in hydrogen storage, hydrogen purification and hydrogenation / dehydrogenation applications [5][6][7][8][9].These phenomena are manifestations on the importance of elucidating the absorption of hydrogen to develop sustainable hydrogen-based economy.…”

First Principles Study on the Adsorption and Dehydrogenation of Borohydride on Mn(111)

“…An ideal alternative source must be highly renewable, environmental friendly, relatively inexpensive, easily accessible, and easy to manufacture [1]. Hydrogen has been foreseen as a viable source of alternative energy through fuel cells [2][3][4][5][6][7]. Improvements were attained through the use of different fuels such as methanol, ethanol, hydrocarbons, and hydrazine [8].…”

“…There have been a number of theoretical studies on the possibility of using 3d transition metals [3,8,24] as anode catalysts for different fuel cells because of their low cost. As an initial step of looking at the possibility of using manganese as a non-precious anode material for DBFC, we explored the mechanism of adsorption and dehydrogenation of borohydride molecule on Mn(111) through first principles calculations within Density Functional Theory (DFT).…”

Surface as a Foundation to Realizing Designer Materials

“…This leads to the development of novel materials in the field of nanotechnology, where advances in material science provide improvement in areas such as solar cells, nanofibers, sensors and ultra light materials. Some recent applications of CMD R ⃝ on fuel cell technology are on studies related to finding potential alternatives to the very expensive platinum, commonly used as a catalyst at the electrodes of the fuel cell [10,11]. The CMD R ⃝ process that is originally developed by our group is shown in Fig.…”