A high energy density azobenzene/graphene hybrid: a nano-templated platform for solar thermal storage

Abstract

Effective conversion of light into heat is an emerging field showing great potential for large-scale applications, markedly driven by novel molecules and structures. Unfortunately, until now, it is still hindered by a low storage capacity and short-time storage. A nano-template for covalently attaching new azobenzene chromophores on graphene as solar thermal fuels is presented here, in which the intermolecular hydrogen bond and proximity-induced interaction, resulting from a high functionalization density and inter-planar bundling interaction, remarkably improve both the storage capacity and lifetime. This nanoscopic template exhibits a high energy density up to 112 W h kg⁻¹ and long-term storage with a half-life of more than one month (33 days), which are also confirmed by the calculations using density functional theory, simultaneously maintaining an excellent cycling stability tuned by visible light for 50 cycles. Our work develops a promising class of solar thermal fuels with high energy density, which outperform previous nano-materials and are comparable to commercial soft-packing Li-ion batteries.