Nanostructured MoS2 grafted by anthraquinone for energy storage

Two-dimensional materials such as molybdenum disulfide (MoS 2 ) can be employed as an electrode material in energy systems due its good electrical conductivity and high reachable capacity/capacitance. We demonstrate the concept of a covalent modification of nanostructured MoS 2 with anthraquinone (AQ) molecules through diazonium salt chemistry for electrochemical capacitors and lithium-ion storage. AQ molecules are chemically bonded to MoS 2 which was proved experimentally by spectroscopic techniques. Here, AQ is grafted (ca. 20 wt%) to the outer surface of nanostructured MoS 2 , but also confined within the MoS 2 interlayer spacing. Modified AQ-MoS 2 exhibited faradaic response which improved the overall charge stored from 191 F g −1 (461 F cm −3 ) to 263 F g −1 (631 F cm −3 ) at 0.2 A g −1 in 1 M H 2 SO 4 . The process of intercalation of ions within interlayer spacing of AQ-MoS 2 was not hindered by the presence of confined AQ molecules. Impedance spectroscopy and voltammetry analysis revealed comparable non-diffusion limited response of MoS 2 before and after modification. The MoS 2 modification was likely conducted on the defect sites limiting the catalytic activity of MoS 2 towards hydrogen evolution improving stability of electrodes. In organic medium, the pseudocapacitive response of MoS 2 , enhanced by additional redox reactions of grafted AQ was observed during lithium-ion storage. • Nanostructured molybdenum sulfide (MoS 2 ) successfully grafted by anthraquinone (AQ). • Grafting was on the outer surface of MoS 2 as well as within interlayer spacing. • AQ-MoS 2 improved capacitance due to redox behavior of grafted molecules.