Carbon-Nanotube-Incorporated Graphene Scroll-Sheet Conjoined Aerogels for Efficient Hydrogen Evolution Reaction

Developing low-cost Pt-free hydrogen evolution reaction (HER) electrocatalyst is highly desired in exploiting hydrogen as a sustainable new energy carrier. Herein, hierarchically structured graphene-carbon nanotube aerogel-MoSe2 hybrid (GCA-MoSe2) was constructed as efficient HER electrocatalysts. GCA was facilely fabricated by direct freeze-drying of graphene oxide (GO)-carbon nanotube (CNT) hybrid dispersion, with subsequent carbonization. Through a shock cooling method, a unique scroll-sheet conjoined architecture could be formed in GCA, which can function as highly conductive skeleton, thus facilitating the transport of electrons through the whole hybrids. Furthermore, CNTs acting as "spacers" between graphene layers can efficiently impede their restacking, thus giving full play to the superior electrical conductivity of graphene. The hierarchical porous aerogel skeleton could allow full impregnation of electrolyte, accelerating the ion diffusion kinetics. Benefiting from the three-dimensional (3D) network of GCA, MoSe2 nanosheets can grow densely and perpendicularly on the aerogel, preventing them from aggregation to maximize the number of catalytic active sites on the edges. The ensemble of these benefits makes the hybrid an efficient electrocatalyst for HER, which exhibits an onset potential of 113 mV, small Tafel slope of 68 mV decade(-1) and good stability. Such a simple method of immobilizing guest nanosheets/particles in the host of GCA opens a new avenue for manufacturing macroscopic electrode materials in large scale.