Mn-Doped NiMoO₄ Mesoporous Nanorods/Reduced Graphene Oxide Composite for High-Performance All-Solid-State Supercapacitor

Abstract

Mn-doping has great influence on the structural and electrical properties of NiMoO 4 , which plays an important role in determining its electrochemical activities. In this work, Mn-doped NiMoO 4 was prepared. Structural characterization and theoretical calculation reveal that Mn-doped NiMoO 4 (Mn 0.1 Ni 0.9 MoO 4 ) has smaller unit cell parameters and is more reactive than NiMoO 4 because of the defects produced by Mn-doping. On the basis of that, we prepared a composite consisting of Mn 0.1 Ni 0.9 MoO 4 mesoporous nanorods and reduced graphene oxide (Mn 0.1 Ni 0.9 MoO 4 /rGO), which was assembled into a symmetrical all-solidstate device as electrode material, with alkaline poly(vinyl alcohol) as solid-state electrolyte. The device shows a good specific capacitance of 109.3 F•g −1 at 1 A•g −1 in a rather wide voltage range of 0−1.8 V, exhibits an excellent cycling stability with 96.1% of the capacitance retained after 200 cycles, and delivers a high energy density of 49.2 Wh•kg −1 at 1800 W•kg −1 . The all-solid-state supercapacitor owns superior flexibility and maintains 83.6% of its initial specific capacitance under the bent condition. When tested in a three-electrode system, the Mn 0.1 Ni 0.9 MoO 4 /rGO composite exhibits a maximum specific capacitance of 688.9 F•g −1 at 0.5 A•g −1 that is much better than NiMoO 4 and Mn 0.1 Ni 0.9 MoO 4 . The results show that the Mn 0.1 Ni 0.9 MoO 4 /rGO composite stands out as a kind of transition-metal-doped electrode material for flexible all-solid-state supercapacitors.

Synchronous Defect and Interface Engineering of NiMoO4 Nanowire Arrays for High-Performance Supercapacitors

“…The diffraction peaks located at 14.3°, 24.0°, 25.4°, 28.9°, 32.6°, 37.1°, 38.7°, 41.3°, and 47.4° corresponded to the (110), (021), (−112), (220), (022), (−113), (−132), (040), and (−204) crystal planes of orthorhombic NiMoO 4 (JCPDS card No. 86-0361) [ 37 ]. Compared to the NiMoO 4 NWAs samples, the NiMoO 4− x @C sample exhibited a slightly lower diffraction peak intensity possibly due to the covering of carbon on the NiMoO 4 surface as well as the reduced crystallinity of NiMoO 4 with increased structural defects.…”

“…To overcome the poor electronic conductivity of pristine NiMoO 4 , various NiMoO 4 /carbon composites have been synthesized by hybridizing NiMoO 4 nanostructures with graphene [ 30 , 31 ], carbon nanotubes [ 32 ], conducting polymers [ 33 ], and porous carbon architectures [ 34 , 35 ] Alternatively, intentional doping of NiMoO 4 with several kinds of heteroatoms such as Mn [ 36 , 37 ], P [ 38 ], Zn [ 39 ], Ce [ 40 ], or the creation of oxygen vacancies [ 14 , 41 , 42 , 43 ] in the lattice have recently been reported. In addition, NiMoO 4 has also been coupled with other metal oxides [ 44 , 45 , 46 , 47 , 48 , 49 ] or sulfides [ 50 , 51 , 52 ] to form heterostructure electrodes for supercapacitors with improved electrochemical performances.…”

Zn Metal Atom Doping on the Surface Plane of One-Dimesional NiMoO4 Nanorods with Improved Redox Chemistry

“…27 Moreover, Zn has been chosen because of its nontoxicity and abundance in nature. Recently, the effect of manganese 28 and iron 29 doping on nickel molybdate nanorods was demonstrated in the literature. However, till date, there are not many reports on employing Zn dopants for improving the electrochemical activity by modifying the active NiMoO 4 sites at the atomic level.…”

Recent advances in solid‐state supercapacitors: From emerging materials to advanced applications

“…The hydrothermal method is attributed to be environmental-friendly because of its lesser energy consumption compared to the sintering process requiring high temperature, which can also be readily scale-up. 310 Ranging from zero-to three-dimensional morphologies (such as quantum dots, 311 nanowires, 312 nanodendrites, 313 nanosheets, 314,315 nanospheres, 316 nanoflowers 317 ), various nanomaterials for SSC electrodes have been synthesized using hydrothermal/solvothermal strategies. [318][319][320][321][322][323][324][325][326]…”