Surface energy-driven ex situ hierarchical assembly of low-dimensional nanomaterials on graphene aerogels: a versatile strategy

Abstract

Hybrid aerogels composed of functional low-dimensional nanomaterials (LDNs) and reduced graphene oxide (rGO) hold great promise in fields ranging from catalysis to energy storage and conversion. However, the challenge of developing a general strategy for the hierarchical assembly of LDNs on rGO aerogels remains unsolved. Here, we propose a surface energy-driven strategy for ex situ hierarchical assembly of LDNs on preformed rGO aerogels. This strategy is versatile and generally applicable to a broad variety of LDNs regardless of their composition, shapes, and dimensionalities. Experimental and simulation results reveal that the organically modified, energetically stable LDNs thermodynamically tend to uniformly and densely reside on the rGO aerogels, thereby reducing the surface energy of the aerogels and the free energy of the solution system. Four kinds of LDNs are successfully decorated on rGO aerogels, including 0D Mn₃O₄ nanocubes and Ag nanospheres, and 1D TiO₂ nanochains and SnO₂ nanowires. As a possible application harnessing the unique structural features of these materials, the Mn₃O₄@rGO hybrid aerogels were tested as anodes in lithium ion battery half cells, delivering a high reversible lithium storage capacity (1.35 mA h cm⁻² at 3.5 mA cm⁻²) at high mass loading density (up to 7 mg cm⁻²).