MoSe2 Embedded CNT-Reduced Graphene Oxide Composite Microsphere with Superior Sodium Ion Storage and Electrocatalytic Hydrogen Evolution Performances

Abstract

Highly porous MoSe 2 -reduced graphene oxide-carbon nanotube (MoSe 2 -rGO-CNT) powders were prepared by a spray pyrolysis process. The synergistic effect of CNTs and rGO resulted in powders containing ultrafine MoSe 2 nanocrystals with a minimal degree of stacking. The initial discharge capacities of MoSe 2 -rGO-CNT, MoSe 2 -CNT, MoSe 2 -rGO, and bare MoSe 2 powders for sodium ion storage were 501.6, 459.7, 460.2, and 364.0 mA h g –1, respectively, at 1.0 A g –1 . The MoSe 2 -rGO-CNT composite powders had superior cycling and rate performances compared with the MoSe 2 -CNT, MoSe 2 -rGO composite, and bare MoSe 2 powders. The electrocatalytic activity of MoSe 2 -rGO-CNT in the hydrogen evolution reaction (HER) was also compared with that of MoSe 2 -CNT, MoSe 2 -rGO, and bare MoSe 2 . MoSe 2 -rGO-CNT composite powders exhibited an overpotential of 0.24 V at a current density of 10 mA cm –2, which was less than that of MoSe 2 -CNT (0.26 V at 10 mA cm –2 ), MoSe 2 -rGO (0.32 V at 10 mA cm –2 ), and bare MoSe 2 (0.33 V at 10 mA cm –2 ). Tafel slopes for the MoSe 2 -rGO-CNT, MoSe 2 -CNT, MoSe 2 -rGO, and bare MoSe 2 powders were 53, 76, 86, and 115 mV dec –1, respectively. Because a large electrochemical surface area and ultrafine MoSe 2 nanocrystals, the MoSe 2 -rGO-CNT composite possesses more active sites than the MoSe 2 -CNT, MoSe 2 -rGO composite, and bare MoSe 2 powders with extensive stacking and large crystalline size, which provide greater catalytic HER activity.