Fast One-Pot Synthesis of MoS₂/Crumpled Graphene p–n Nanonjunctions for Enhanced Photoelectrochemical Hydrogen Production

Aerosol processing enables the preparation of hierarchical graphene nanocomposites with special crumpled morphology in high yield and in a short time. Using modular insertion of suitable precursors in the starting solution, it is possible to synthesize different types of graphene-based materials ranging from heteroatom-doped graphene nanoballs to hierarchical nanohybrids made up by nitrogen-doped crumpled graphene nanosacks that wrap finely dispersed MoS₂ nanoparticles. These materials are carefully investigated by microscopic (SEM, standard and HR TEM), diffraction (grazing incidence X-ray diffraction (GIXRD)) and spectroscopic (high resolution photoemission, Raman and UV−visible spectroscopy) techniques, evidencing that nitrogen dopants provide anchoring sites for MoS₂ nanoparticles, whereas crumpling of graphene sheets drastically limits aggregation. The activity of these materials is tested toward the photoelectrochemical production of hydrogen, obtaining that N-doped graphene/MoS₂ nanohybrids are seven times more efficient with respect to single MoS₂ because of the formation of local p–n MoS₂/N-doped graphene nanojunctions, which allow an efficient charge carrier separation.