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

Abstract

Molybdenum disulfide (MoS 2 ) 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 MoS 2 and enhance its ion storage and electrocatalytic performance. In this study, a plasma-assisted nitrogen-doped 1T/2H MoS 2 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 MoS 2 nanosheets via roomtemperature low-power N 2 plasma, and the 1T/2H hybrid phase is maintained. As expected, the 1T/2H MoS 2 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 MoS 2 -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.

Two-Dimensional Confined Synthesis of Metastable 1T-Phase MoS2 Nanosheets for the Hydrogen Evolution Reaction

“…The optimal N-MoS 2 /rGO presents an outstanding performance with the lowest overpotential (130 mV) to reach 10 mA•cm −2 in comparison with MoS 2 (243 mV), N-MoS 2 (223 mV), and MoS 2 /rGO (193 mV) (Figures 4A and S13). The HER overpotential at 10 mA•cm −2 is also lower than or comparable to those obtained by reported MoS 2 or Mo-based electrocatalysts (Table S1), such as Metallic-MoS 2 (175 mV@10 mA• cm −2 ), 1 defective-MoS 2 /rGO (154.77 mV@10 mA•cm −2 ), 33 exfoliated 1T-MoS 2 (187 mV@10 mA•cm −2 ), 34 1T-MoS 2 (187 mV@10 mA•cm −2 ), 35 1T-MoS 2 /CFP (219 mV@10 mA• cm −2 ), 36 MNG-40 (157 mV@10 mA•cm −2 ), 37 1T/2H-MoS 2 heterostructure (131 mV@10 mA•cm −2 ), 38 DBC-MoS 2 -PANI2 (196 mV@10 mA•cm −2 ), 39 Mo/S (0.2) −450 (130 mV@10 mA•cm −2 ), 40 and Co 9 S 8 /MoS x (161 mV@10 mA• cm −2 ). 41 1T-MoS 2 also accelerates the HER kinetics and promotes the electrocatalytic activity.…”

Even Incorporation of Nitrogen into Fe0 Nanoparticles as Crystalline Fe4N for Efficient and Selective Trichloroethylene Degradation

“…Tafel tests were characterized to further assess the impact of N content on the corrosion rate of these materials, as well as their ability to release electrons . Generally, the polarization voltage ( E corr ) and the cathode slope could reflect the electron transfer and the degree of reduction reactions, respectively. , Polarization curves (Figure d and Table S5) show that the measured values of both E corr and cathode slope for the nitridated materials were much smaller than that of nZVI, suggesting the accelerated electron transfer, lower overpotential of catalytic reactions, and more thorough reduction reactions. In addition, the measured values of the cathode slope tended to decrease as the increase of the N content, and the nitridated material with a lower cathode slope value also shows higher corrosion current density ( I corr ), indicating their high reactivity with TCE as discussed below.…”

High-Performance MnO2 Nanowire/MoS2 Nanosheet Composite for a Symmetrical Solid-State Supercapacitor

“…The energy and power density were derived from galvanostatic charging–discharging at various current densities. The energy density and power density are evaluated using eqs and , respectively. where E is the energy density, P is the power density, C sp is the gravimetric specific capacitance calculated through GCDs, V is the voltage window, and Δ t is the discharge time. ,,− …”

“…The layered structure provides more surface area for charge storage and different oxidation states from +2 to +6 of the central Mo atoms to increase the pseudocapacitance. Generally, the 1T phase exhibits an improved hydrophilic behavior and an excellent electrical conductivity higher than that of 2H–MoS 2 , which directs to a higher specific capacitance in a liquid electrolyte. − Accordingly, 1T MoS 2 could be a suitable electrode material for manufacturing high-performance solid-state SCs. On the other hand, layered 1T-MoS 2 nanosheets lead to restacking due to the out-of-plane van der Waals (vdW) force of attraction between adjacent layers, reducing the active surface area and preventing effective electrolyte ion diffusion, ensuing in a faster decay of electrochemical performance. − To control the reaggregation and possible phase change of 1T-MoS 2 , which leads to poor performance, a solution-processable method to get MoS 2 nanosheets with stable dispersion is required to explore the spectrum of practical uses.…”