Vertically Standing MnO₂ Nanowalls Grown on AgCNT-Modified Carbon Fibers for High-Performance Supercapacitors

Abstract

Large-scale ultrathin γ-MnO2 nanosheets form a continuous wall-like enclosed network directly grown onto the surface of carbon cloth (CC) fibers. In a simple green electrochemical deposition process, the CCs were pretreated under acid condition and subsequently attached by carbon nanotubes with silver nanoparticles (AgCNTs), forming a three-dimensional (3D) hierarchical heterostructure of MnO2-decorated AgCNT CC fibers (MnO2-AgCNT-CC). The structure, phase purity, and morphology of the samples were characterized by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical techniques. The MnO2-AgCNT-CC composite had high specific capacitance (up to 325 F/g at 1 A/g) and long cycle-life stability. These outstanding electrochemical characteristics were attributed to the unique 3D porous MnO2 nanowalls and AgCNT composites, increasing ion-accessible surface area and shortening cation/electron transportation pathways, thus endowing the electrode with carbon fibers with good capability and long-term cycling stability, lucrative for large-scale energy storage applications. The simplicity of the developed fabrication process is appealing to the large-scale production of MnO2-based materials on commercial CC fibers and for adaptation to roll-to-roll manufacturing through a continuous-fabrication process, widening its applicability.

Enhanced Coagulation with Mn(III) Pre-Oxidation for Treatment of Micro-Polluted Raw Water

“…Two Mn 2p peaks were detected, Mn 2p 3/2 peak at 641.58 eV and the Mn 2p 1/2 peak was shown at 653.28 eV. The binding energy of Mn 2p with a spin-energy separation of 11.7 eV was in good agreement with the binding energy of MnO 2 [47,57], indicating that MnO 2 was indeed generated in Mn(III)+C/S. The in-situ formed MnO 2 could act as the nuclei for heterogeneous coagulation [58].…”

In situ hydrothermal synthesis of MnO2 nanowires/wood derived activated carbon hollow fibers composite and its application in supercapacitor

“…g -1 (Fig. 3e), which is competitive with those of the recently reported supercapacitors fabricated on carbon fibres (Ko et al 2018, Ye et al 2017, Sun et al 2017. Moreover, the specific capacitance of 70Mn@ACHF was higher than that of the other samples for all of the various current densities.…”

Three-Dimensional Self-Standing and Conductive MnCO3@Graphene/CNT Networks for Flexible Asymmetric Supercapacitors

“…Figure b shows the CV curves for the MnCO 3 @graphene/CNT electrode with increasing scan rate from 5–100 mV s –1 . The shape of the curves is well-retained up to 100 mV s –1 , revealing rapid charge transportation characteristic. − Figure c shows the GCD curves of MnCO 3 @graphene/CNT under various current densities. All the curves show great symmetry and nearly linear slopes, indicating the capacitive characteristic and excellent reversibility of the MnCO 3 @graphene/CNT electrode.…”