Arrayed CNx NT–RuO2 nanocomposites directly grown on Ti-buffered Si substrate for supercapacitor applications

Directly-Grown Hierarchical Carbon Nanotube@Polypyrrole Core-Shell Hybrid for High-Performance Flexible Supercapacitors

A hierarchical carbon nanotube-polypyrrole (CNT-PPy) core-shell composite was fabricated by growing CNTs directly on carbon cloth (CC) as a skeleton followed by electropolymerization of PPy with controlled polymerization time. Direct fabrication of electroactive (CNT-PPy) materials on the flexible CC electrode could reduce the interfacial resistance between the electrode and electrolyte and improve the ion diffusion. The supercapacitor electrode based on optimized PPy/CNT-CC exhibits excellent electrochemical performance, with the highest gravimetric capacitance being roughly 1038 F g(-1) per active mass of PPy and up to 486.1 F g(-1) per active mass of the PPy/CNT composite. Notably, excellent flexibility and cycle stability up to 10 000 cycles with only 18 % capacitance loss was achieved. At the same time, the fabricated asymmetric supercapacitor (PPy/CNT-CC∥CNT-CC) shows the maximum power density of 10 962 W kg(-1) at an energy density of 3.9 Wh kg(-1) under the operating potential of 1.4 V. The overall high cycle stability and high performance of the fabricated PPy/CNT-CC flexible electrode is due to the novel binder-free direct growth process.

Hierarchical porous NiCo2O4 nanograss arrays grown on Ni foam as electrode material for high-performance supercapacitors

A novel hierarchical porous NiCo₂O₄ nanograss array directly grown on Ni foam has been constructed via a simple one-step hydrothermal method combined with a calcination treatment, and possessed high electrochemical performance.

Uniformly embedded metal oxide nanoparticles in vertically aligned carbon nanotube forests as pseudocapacitor electrodes for enhanced energy storage

Carbon nanotube (CNT) forests were grown directly on a silicon substrate using a Fe/Al/Mo stacking layer which functioned as both the catalyst material and subsequently a conductive current collecting layer in pseudocapacitor applications. A vacuum-assisted, in situ electrodeposition process has been used to achieve the three-dimensional functionalization of CNT forests with inserted nickel nanoparticles as pseudocapacitor electrodes. Experimental results have shown the measured specific capacitance of 1.26 F/cm(3), which is 5.7 times higher than pure CNT forest samples, and the oxidized nickel nanoparticle/CNT supercapacitor retained 94.2% of its initial capacitance after 10,000 cyclic voltammetry tests.

HIGHLY EFFICIENT HYBRID SUPERCAPACITOR MATERIAL FROM NICKEL-MANGANESE OXIDES/MWCNTs/PEDOT NANOCOMPOSITE

A novel ternary nanocomposite of nickel-manganese oxides/multi-walled carbon nanotubes (NMO/MWCNTs) coated with poly (3,4-ethylenedioxythiophene)(PEDOT) was prepared by chemical oxidation method. The filling of NMO particles inside MWCNTs and the uniform coating of NMO/MWCNTs with PEDOT intensified the capacitive behavior of MWCNTs. The lowest IR drop (0.1 V) and highest specific capacitance (SC) values of 526.55 F/g of NMO/MWCNTs/PEDOT imply it as highly efficient hybrid supercapacitor materials in 6 M KOH electrolyte.

High methanol oxidation activity of well-dispersed pt nanoparticles on carbon nanotubes using nitrogen doping

Pt nanoparticles (NPs) with the average size of 3.14 nm well dispersed on N-doped carbon nanotubes (CNTs) without any pretreatment have been demonstrated. Structural properties show the characteristic N bonding within CNTs, which provide the good support for uniform distribution of Pt NPs. In electrochemical characteristics, N-doped CNTs covered with Pt NPs show superior current density due to the fact that the so-called N incorporation could give rise to the formation of preferential sites within CNTs accompanied by the low interfacial energy for immobilizing Pt NPs. Therefore, the substantially enhanced methanol oxidation activity performed by N-incorporation technique is highly promising in energy-generation applications.

RuO(2) nanoparticles dispersed on carbon nanotubes with high electrochemical activity using N incorporation

The N incorporation into carbon nanotubes (CNTs) supporting ultrafine RuO(2) nanoparticles (NPs) has been studied. With increasing N dopant, the Raman spectrum shifts to higher wavenumbers and x-ray photoelectron spectroscopy results show the intensity ratio of graphene- to pyridine-like bonding is reduced. Cross-sectional scanning electron microscope images reveal that the uniform RuO(2) NPs are dispersed on CNTs at the N(2) flow rate of 20 sccm. Electrochemical (EC) measurements show N-doped CNTs covered with RuO(2) NPs at an N(2) flow rate of 20 sccm provide the optimal capacitive behavior with larger energy density and can be performed at the higher scan rate of 2000 mV s(-1). The distribution of RuO(2) NPs on CNT surfaces deduced from N-induced defect sites is the key point in controlling the capacitive characteristics of CNT-RuO(2) nanocomposites (NCs). The high capacitance is due to the well-dispersed RuO(2) particles on CNTs incorporated with N atoms. Such NCs are promising for energy storage devices with high EC efficiency.