Structurally stable ultrathin 1T-2H MoS2 heterostructures coaxially aligned on carbon nanofibers toward superhigh-energy-density supercapacitor and enhanced electrocatalysis

Metallic 1T MoS2 is a promising anode candidate for supercapacitors due to its intrinsically excellent electrical conductivity and high electrochemical activity. However, it is quite unstable and hard to be massively synthesized through common methods. Herein, structurally stable ultrathin (1-3 layers) in-plane 1T-2H MoS2 heterostructures have been rationally modulated and coaxially aligned on three-dimensional carbon nanofibers (MoS2/CF) through a facile hydrothermal approach for supercapacitors and electrocatalysis. Benefiting from the unique heterostructure, the MoS2/CF composite shows amazing stability with no obvious change after being stored in air for over 36 months. In addition, it presents high specific capacitance of 310 F g(-1) and remarkable rate capability of 78% at 100 mV s(-1). The fabricated asymmetric supercapacitor delivers an impressive energy density of 81.4 Wh kg(-1) in 1 M Na2SO4 solution attributed to the high specific capacitance and large operating voltage range of 2 V. Moreover, the MoS2/CF composite also demonstrates enhanced electrocatalytic activity for hydrogen evolution reaction with a low overpotential of 194 mV at 10 mA cm(-2). The work may promote the developments of high-performance bifunctional energy conversion and storage systems in future.