Surface-Functionalized Nanoporous Carbons for Kinetically Stabilized Complex Hydrides through Lewis Acid–Lewis Base Chemistry

Abstract

Complex metal hydrides are an attractive hydrogen storage option due to their high gravimetric hydrogen capacities, but the re/dehydriding reactions generally possess unfavorable thermodynamics and kinetics. Recent studies have attempted to alter these properties through confinement of complex hydrides in nanoporous substrates. For example, LiBH4 may be melt-infiltrated into a nanoporous carbon (LiBH4@NPC), where electron-withdrawing boron concomitantly incorporates into the substrate, facilitating the wetting of the pores with molten LiBH4. We present results of the surface functionality displayed by incorporation of electron-donating nitrogen into a nanoporous carbon. The presence of pyridinic nitrogen in the substrate, confirmed by XPS analysis, acts as a Lewis base. Our results indicate partial decomposition on melt-infiltration of LiBH4 may produce electron-accepting BH3 defects at the surface of the hydride forming a stabilizing capping layer. Isothermal hydrogen desorption measurements indicate an ...