Graphene/graphene nanoribbon aerogels as tunable three-dimensional framework for efficient hydrogen evolution reaction

Carbon-based materials have emerged as the promising templates of electrocatalysts for hydrogen evolution reaction (HER). In order to enhance the HER activity, the structure of carbon-based materials needs to be carefully engineered to maximize the exposure of active sites, improve the electrical conductivity and shorten the ion diffusion pathway of catalysts. In this work, high-performance electrocatalysts for HER have been constructed based on the graphene/graphene nanoribbon (GGNR) aerogels. In the GGNR aerogels, graphene nanosheets act as the main building blocks of the monolithic aerogels, while large amounts of graphene nanoribbons tightly bridge different graphene nanosheets, which allows intrinsically good electrical contact with electroactive materials. Moreover, the threedimensional porous framework with large surface-to-volume ratio can be tuned by adjusting the amount of graphene nanoribbons, which guarantees the ultrafast and sufficient mass transfer in the catalytic process. All the above factors make GGNR aerogels ideal templates for immobilization of MoS2 nanosheets, a typical noble metal-free hydrogen evolution catalyst. The optimal GGNR@MoS2 hybrid exhibits excellent HER performance, with a low onset potential of -105 mV, a small Tafel slope of 49 mV per decade and a large current density (10.0 mA cm(-2) at eta = 183 mV), making them promising and highly efficient electrocatalyst for hydrogen evolution reaction. (C) 2017 Elsevier Ltd. All rights reserved.