Controllably Doping Nitrogen into 1T/2H MoS2 Heterostructure Nanosheets for Enhanced Supercapacitive and Electrocatalytic Performance by Low-Power N2 Plasma.

Molybdenum disulfide (MoS2) is a promising candidate for use as a supercapacitor electrode material and non-noble-metal electrocatalyst owing to its relatively high theoretical specific capacitance, Pt-like electronic feature, and graphene-like structure. However, insufficient electrochemically active sites along with poor conductivity significantly hinder its practical application. Heteroatom doping and phase engineering have been regarded as effective ways to overcome the inherent limitations of MoS2 and enhance its ion storage and electrocatalytic performance. In this study, a plasma-assisted nitrogen-doped 1T/2H MoS2 heterostructure has been proposed for the first time, resulting in excellent supercapacitor performance and hydrogen evolution reaction activity. XPS, Raman, and TEM analysis results indicate that N atoms have been successfully doped into MoS2 nanosheets via room-temperature low-power N2 plasma, and the 1T/2H hybrid phase is maintained. As expected, the 1T/2H MoS2 heterostructure after a 10 min plasma treatment displayed a much boosted supercapacitive performance with a high specific capacitance of 410 F g-1 at 1 A g-1 and an excellent hydrogen evolution property with a low overpotential of 131 mV vs RHE at 10 mA cm-2 for hydrogen evolution reaction. The excellent performance is superior to most of the recently reported outstanding MoS2-based electrode and electrocatalytic materials. Moreover, the as-assembled flexible symmetric supercapacitor shows a high specific capacitance of 84.8 F g-1 and superior mechanical robustness with 84.5% capacity retention after 2000 bending cycles.