Theoretical study of C60 as catalyst for dehydrogenation in LiBH4

TL;DR

This study uses density functional theory to explore how C60 fullerenes catalyze hydrogen release in LiBH4, revealing that C60 significantly lowers hydrogen removal energies by interacting with BHx- complexes.

Contribution

It provides a detailed theoretical analysis of the catalytic mechanism of C60 in LiBH4, a topic previously focused mainly on titanium-based catalysts.

Findings

C60 reduces hydrogen removal energies in LiBH4

Interaction occurs between BHx- complexes and C60

Mechanism involves stabilization of dehydrogenation intermediates

Abstract

Complex light metal hydrides possess many properties which make them attractive as a storage medium for hydrogen, but typically, catalysts are required to lower the hydrogen desorption temperature and to facilitate hydrogen uptake in the form of a reversible reaction. The overwhelming focus in the search for catalysing agents has been on compounds containing titanium, but the precise mechanism of their actions remains somewhat obscure. A recent experiment has now shown that fullerenes (C$_{60}$) can also act as catalyst for both hydrogen uptake and release in lithium borohydride (LiBH$_4$). In an effort to understand the involved mechanism, we have employed density functional theory to carry out a detailed study of the interaction between this complex metal hydride and the carbon nanomaterial. Considering a stepwise reduction of the hydrogen content in LiBH$_4$, we find that the presence of C$_{60}$ can lead to a substantial reduction of the involved H-removal energies. This effect is explained as a consequence of the interaction between the BH$_x^-$ complex and the C$_{60}$ entity.