Large-Scale Synthesis of Metal-Ion-Doped Manganese Dioxide for Enhanced Electrochemical Performance

Abstract

One-dimensional (1D) MnO2 was widely applied in areas of enzyme biosensors, industrial sieves, and energy storage materials owing to its excellent thermal, optical, magnetic, and chemical features. However, its practical application into energy storage devices is often hindered by the bad electronic conductivity (from 10(-5) to 10(-6) S cm(-1)). As is widely known, doping with hetero elements is an efficient way to enhance the electronic conductivity of metal oxides. Herein, a novel and simple molten-salt method is developed to achieve a large-scale preparation of 1D MnO2 nanowires. Such an approach also realizes the easy tuning of electrical properties through doping with different transition metal ions. On the basis of first-principle calculation as well as four-probe measurement, we determined that the conductivity of the doped MnO2 nanowires can be promoted efficiently by utilizing such protocol. Meanwhile, a possible doping route is discussed in detail. As a result, a superior electrochemical performance can be observed in such metal ions (M(+))-doped nanowires. Such high-quality M(+)-doped MnO2 nanowires can satisfy a broad range of application needs beyond the electrochemical capacitors.

One‐Step Synthesis of Vacancy‐Rich MnO2−x/Reduced Graphene Oxide Composite Film for High Electrochemical Performance

“…There exist two main routes to improve the electronic conductivity of α ‐phase MnO 2 including doping with heteroatom and compounding with high conductive materials . Doping approach can efficiently alter the intrinsic conductivity of semiconductor, but the homogeneity and content of doping atoms cannot be precise controlled.…”

Experimental and Theoretical Investigation of the Effect of Oxygen Vacancies on the Electronic Structure and Pseudocapacitance of MnO2

“…First, the band gaps of pure MnO 2 and MnO 2 containing oxygen vacancies were analyzed. As shown in Figure 9 a and c, the band gap of pure MnO 2 was 1.13 eV, which was consistent with previous work, suggesting the results of the calculations were accurate. Some additional defect levels appeared in the forbidden band for MnO 2 containing oxygen vacancies and the valence band (VB) and conduction band (CB) moved toward a higher energy, which improved the carrier concentration and further enhanced the electrical conductivity.…”

One‐Dimensional Nanostructured Pseudocapacitive Materials: Design, Synthesis and Applications in Supercapacitors

“…Benefitting from the unique ultralayered mesoporous architecture and binary Co/Ni electroactive sites, the as‐obtained NiCo 2 O 4 NWs exhibits high SCs, good rate capability, and long cycling life. Yu and co‐workers reported a molten‐salt method to prepare ultralong MnO 2 NWs . After doping with different transition metal ions, the FeMnO, CoMnO, NiMnO, and CuMnO NWs are obtained with a diameter of approximately 40 nm and an average length of 10 μm, as well as uniform single crystal structure (Figure b–e).…”

“…Copyright 2011 ACS Publication. TEM and HRTEM images of b), b1) FeMnO, c), c1) CoMnO, d), d1) NiMnO, and e), e1) CuMnO . Reported with permission from ref 112.…”