Aerosol synthesis of molybdenum diselenide–reduced graphene oxide composite with empty nanovoids and enhanced hydrogen evolution reaction performances

초록

MoSe2–reduced graphene oxide (rGO) composite powders with unique structures containing empty nanovoids and excellent hydrogen evolution reaction (HER) performances were prepared using a pilot-scale spray-drying process. One-step post-treatment of the spray-dried powders produced the macroporous MoSe2–rGO composite with empty nanovoids through an intermediate MoO3–Se–GO composite. Ultrafine MoSe2 nanocrystals, which consisted of a few layers and were several nanometers in size, were uniformly dispersed on the surfaces of the MoSe2–rGO composite powders with the optimal rGO contents. The MoSe2–rGO–M composite (20 wt% rGO) had the optimized porous structure with a uniform distribution of MoSe2 nanocrystals and enough the rGO content for a fast electron transport, and thus exhibited the highest HER activity. The MoSe2–rGO–M composite powders exhibited a current density of 10 mA cm−2 at a small overpotential of 0.21 V, which was lower than that of bare MoSe2 (10 mA cm−2 at 0.31 V). The Tafel slopes for bare MoSe2 and MoSe2–rGO–M composite powders were 120 and 57 mV dec–1, respectively. The synergistic effects of rGO sheets and MoSe2 nanocrystals and the unique porous structure resulted in outstanding HER performance with a small Tafel slope and overpotential.

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