Date of Award

12-1-2012

Degree Name

Master of Science

Department

Chemistry

First Advisor

Ge, Qingfeng

Abstract

Carbon-based materials have attracted great attention over past few years in hydrogen storage applications. In particular, nanofibrous carbon working as support for sodium alanate exhibits great improvement in the kinetics of H2 releasing/uptaking. Herein, we used graphene with various dopants to simulate the carbon materials and performed a periodic density functional theory study on the impact of the modifications on the hydrogen interaction in the supported sodium alanate. Our results showed that the impact of various defects and dopants can be categorized in groups: (i) Pristine graphene and pentagon-heptagon (5-7) pair defective graphene, as well as nitrogen and sulfur doped graphene do not promote H2 formation. (ii) Carbon vacancies, as well as boron and chlorine doped systems, cause instantaneous H2 formation. (iii) Oxygen, phosphor and fluorine doped graphene led to the formation of a meta-stable di-hydrogen state with a H-H distance of ~ 0.96 Å. In addition, we confirmed the importance of van der Waals interaction in our system.

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