Self-Assembly of Mesoporous Nanotubes Assembled from Interwoven Ultrathin Birnessite-type MnO2 Nanosheets for Asymmetric Supercapacitors

Abstract

Porous nanotubes comprised of MnO2 nanosheets were fabricated with a one-pot hydrothermal method using polycarbonate membrane as the template. The diameter and thickness of nanotubes can be controlled by choice of the membrane pore size and the chemistry. The porous MnO2 nanotubes were used as a supercapacitor electrode. The specific capacitance in a three-electrode system was 365 F g−1 at a current density of 0.25 A g−1 with capacitance retention of 90.4% after 3000 cycles. An asymmetric supercapacitor with porous MnO2 nanotubes as the positive electrode and activated graphene as the negative electrode yielded an energy density of 22.5 Wh kg−1 and a maximum power density of 146.2 kW kg−1; these values exceeded those reported for other MnO2 nanostructures. The supercapacitor performance was correlated with the hierarchical structure of the porous MnO2 nanotubes.

Sintesis MnO2 Lapisan Nipis Poros menggunakan Templat Silika Alumina-Aptes: Aplikasi Penjerapan Pewarna

“…Jalur 457 cm -1 menunjukkan kehadiran getaran Mn-O dan Mn-O-Mn bagi unit MnO 6 oktahedron dan jalur pada 3441 dan 1646 cm -1 masing-masing menunjukkan getaran regangan dan bengkokan kumpulan OH daripada molekul air (Zhu et al 2006). Jalur pada 1072 cm -1 menunjukkan kehadiran getaran bengkokan kumpulan OH pada permukaan logam (Huang et al 2014). Selain itu juga, terdapat perbezaan antara spektrum FTIR dengan jalur kumpulan alifatik CH 2 yang wujud pada jalur 2919 dan 1480 cm -1 dan getaran bengkokan NH 2 bagi SiO 2 -NH 2 yang wujud pada jalur 1591 cm -1 sebelum tindak balas sonokimia tidak lagi kelihatan dalam spektrum selepas tindak balas.…”

Tailoring Kirkendall Effect of the KCu7S4 Microwires towards CuO@MnO2 Core-Shell Nanostructures for Supercapacitors

“…However, the poor electronic conductivity of MnO 2 ($10 À5 -10 À6 S cm À1 ) is a limiting factor in achieving its theoretical specific capacitance [14,15]. Some efforts have been made to improve the performance of MnO 2 by creating various nanostructures, such as nanotubes [16], nanopillars [17], core/shell nanowires [18,19], nanowall films [20,21], and conductive graphene or polymers supported MnO 2 hybrid materials [22,23].…”

Correlation among physical and electrochemical behaviour of nanostructured electrolytic manganese dioxide from leach liquor and synthetic for aqueous asymmetric capacitor

“…It is worth mentioning here that, a similar current response and shape have been observed for the MnO 2 reported in the literature for aqueous capacitors. 29,30 The integrated areas of the CV profile (in Fig. 6b) are proportional to the sweep rates (1, 2, 5 and 10 mV s À1 ) illustrate the electrochemical utilization of MnO 2 is enhanced through the fast redox reactions.…”

“…33,34 The cations and anions from the NaOH electrolyte are adsorbed on the activated carbon layer during the anodic process while they are desorbed during the reverse scan. 30,33 With increasing scan rate, the shape of CV is gradually distorted from rectangular to elliptical. At higher scan rates, the material is still reversible with an excellent current response but the distorted shape of CV curve implies sluggish OH À ion transport from the electrolyte to the carbon electrode is being limited on the surface rather in the bulk.…”