Herein, we demonstrate the enhanced pseudocapacitive performance of a MoS 2 -based flexible supercapacitor by the co-doping strategy of cations and anions. The MoS 2 nanosheet arrays on carbon cloth are directly doped with N and Co atoms through a simple hydrothermal process. The obtained cation and anion co-modified MoS 2 (N-Co-MoS 2 ) shows improved electron transport efficiency and enhanced active sites for MoS 2 . According to the first-principles calculations, N-Co-MoS 2 has a unique band structure and high electrical conductivity. As expected, N-Co-MoS 2 shows higher capacitive performance with 5072.5 mF cm −2 and a better cycle life (retaining 100% capacitance after 10,000 cycles) than pure MoS 2 . Furthermore, a solid-state flexible N-Co-MoS 2 supercapacitor device is fabricated to demonstrate excellent mechanical stability with a specific capacitance of 3236 mF cm −2 and a stable cycle capacitance of 75.56% after 5000 cycles. In our work, we have provided a reference for preparing MoS 2 -based materials with good supercapacitive performance.
In this paper, the geometric and electronic structure of four gas molecules, including CH4, CH2O, CH3Cl and C6H6, on pristine and Cu/Ni‐modified C3N monolayer are investigated by using First principles. The calculations show that the Cu/Ni‐doping can effectively strengthen the gas adsorption ability of C3N. Upon gas‐C3N configuration, the adsorption energies are CH2O (0.11 eV) > C6H6 (0.09 eV) > CH3Cl (0.08 eV) > CH4 (0.05 eV). For Cu‐C3N configuration, the adsorption energies are C6H6 (3.26 eV) > CH3Cl (3.24 eV) > CH4 (3.22 eV) > CH2O (3.13 eV). For Ni‐C3N configuration, the adsorption energies are CH2O (1.48 eV) > C6H6 (0.66 eV) > CH3Cl (0.39 eV) > CH4 (0.11 eV). It is worth mentioning that the magnetic moment is reduced to 0 µB when CH2O are adsorbed on Cu/Ni‐C3N, and the maximum charge transfer is 0.71 e, 0.62 e, respectively. Moreover, its optical properties of adsorption of Volatile organic compounds (VOCs) gas molecules are studied. It can be found that the two main absorption peaks locate at 3.0 × 105 cm−1 nm and 2.8 × 105 cm−1 nm at the range of ultraviolet and visible light. The calculated results provide the theoretical reference for Cu‐C3N‐based VOCs sensors.
In this paper, a monolayer of TiX 2 (X = S, Se) is used to suppress the shuttle effect of polysulfides, thereby accelerating the kinetic process of lower-order polysulfides. The results show that the adsorption energies of the studied TiX 2 for Na 2 S n are all better than those of common electrolytes, and the effect of adsorption on the structure of Na 2 S n is negligible. The calculated results show that the anchoring behavior of TiX 2 to Na 2 S n has no effect on the metallic properties of pristine TiX 2 . On the other hand, the introduction of this material can reduce the diffusion barrier energy of Na 2 S and improve the utilization rate of sulfur more effectively. In conclusion, TiX 2 has suitable adsorption strength, enhances electrical conductivity, and promotes the oxidative decomposition process of polysulfides. It can be theoretically demonstrated that TiS 2 is better than TiSe 2 in improving the performance of sodium-sulfur batteries and is more suitable as an anchoring material (AM) for sodium-sulfur batteries.
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