Pseudocapacitive Effects of Multi-Walled Carbon Nanotubes-Functionalised Spinel Copper Manganese Oxide

Spinel copper manganese oxide nanoparticles combined with acid-treated multi-walled carbon nanotubes (CuMn₂O₄/MWCNTs) were used in the development of electrodes for pseudocapacitor applications. The CuMn₂O₄/MWCNTs preparation involved initial synthesis of Mn₃O₄ and CuMn₂O₄ precursors followed by an energy efficient reflux growth method for the CuMn₂O₄/MWCNTs. The CuMn₂O₄/MWCNTs in a three-electrode cell assembly and in 3 M LiOH aqueous electrolyte exhibited a specific capacitance of 1652.91 F g^-1 at 0.5 A g^-1 current load. Similar investigation in 3 M KOH aqueous electrolyte delivered a specific capacitance of 653.41 F g^-1 at 0.5 A g^-1 current load. Stability studies showed that after 6000 cycles, the CuMn₂O₄/MWCNTs electrode exhibited a higher capacitance retention (88%) in LiOH than in KOH (64%). The higher capacitance retention and cycling stability with a Coulombic efficiency of 99.6% observed in the LiOH is an indication of a better charge storage behaviour in this electrolyte than in the KOH electrolyte with a Coulombic efficiency of 97.3%. This superior performance in the LiOH electrolyte than in the KOH electrolyte is attributed to an intercalation/de-intercalation mechanism which occurs more easily in the LiOH electrolyte than in the KOH electrolyte.

Nanoforest: Polyaniline Nanotubes Modified with Carbon Nano-Onions as a Nanocomposite Material for Easy-to-Miniaturize High-Performance Solid-State Supercapacitors

This article describes a facile low-cost synthesis of polyaniline nanotube (PANI_NT)–carbon nano-onion (CNO) composites for solid-state supercapacitors. Scanning electron microscopic (SEM) analyses indicate a uniform and ordered composition for the conducting polymer nanotubes immobilized on a thin gold film. The obtained nanocomposites exhibit a brush-like architecture with a specific capacitance of 946 F g⁻¹ at a scan rate of 1 mV s⁻¹. In addition, the nanocomposites offer high conductivity and a porous and well-developed surface area. The PANI_NT–CNO nanocomposites were tested as electrodes with high potential and long-term stability for use in easy-to-miniaturize high-performance supercapacitor devices.

Realizing an Asymmetric Supercapacitor Employing Carbon Nanotubes Anchored to Mn3O4 Cathode and Fe3O4 Anode

A facile route to anchor pseudocapacitive materials on multiwalled carbon nanotubes (CNTs) to realize high-performance electrode materials for asymmetric supercapacitors (ASCs) is reported. The anchoring process is developed after direct decomposition of metal-hexacyanoferrate complex on the CNT surface. Transmission electron microscopy (TEM) analysis reveals that the nanoparticles (NPs) are discretely attached over the CNT surface without forming a uniform layer, thus making most of the entire NP surface available for electrochemical reactions. Accordingly, CNT-Mn₃O₄ nanocomposite cathode shows significantly improved capacitive performance as compared to pristine CNT electrode, validating the efficacy of designing the composite electrode. With CNT-Fe₃O₄ nanocomposite as the paired anode, the hybrid ASC delivers a specific capacitance of 135.2 F/g at a scan rate of 10 mV/s within a potential window of 0-1.8 V in the aqueous electrolyte and retains almost 100% of its initial capacitance after 15,000 cycles. The serially connected ASCs can power commercial light-emitting diodes (LEDs) and mobile phones, reflecting their potential in next-generation storage applications.

Self-assembled Mn3O4 nano-clusters over carbon nanotube threads with enhanced supercapacitor performance

Self-assembled Mn₃O₄@CNT nano-clusters with improved capacitance and cyclic stability designed for supercapacitor application.

A new stable Pd–Mn3O4 nanocomposite as an efficient electrocatalyst for the hydrogen evolution reaction

A galvanic exchange reaction-mediated one-pot synthesis of Pd–Mn₃O₄ nanocomposites for excellent electrocatalytic activity and stability towards the hydrogen evolution reaction.

An electrochemically deposited graphene@Mn3O4 composite film for supercapacitors

A graphene@Mn₃O₄ composite film with a 3D nanoporous network structure has been successfully fabricated via electrochemical deposition.