Preparation and characterization of iridium dioxide–carbon nanotube nanocomposites for supercapacitors

Abstract

A thin film of novel hierarchical structure, suitable for supercapacitor applications, has been developed through combining conductive multi-wall carbon nanotubes (MWCNTs) and square IrO(2) nanotubes (IrO(2)NT) of nanometer size. Synthesis of this hierarchical structure with open porosity is performed by depositing IrO(2) short tubes densely along the long wires of carbon nanotube on a substrate of stainless steel. A IrO(2) tube of rutile structure grows in the [001] direction, with an opening at its top, surrounded by very thin walls. The IrO(2) addition on the MWCNT template increases the capacitance of the CNT thin film effectively, because of pseudocapacitance of the IrO(2) surface. For this particular composite, featured with two tubular nanostructures, the specific capacitance increases from 15 F g(-1) (MWCNT) to 69 F g(-1) (IrO(2)NT/MWCNT), measured using the galvanostatic discharge experiment. Its property of fast retrieval of the stored charge is assured in the impedance measurement, showing that the internal resistance of the IrO(2)NT/MWCNT nanocomposite electrode is lower than that of the bare MWCNTs.

Electrochemical impedance studies of IrO 2 catalysts for oxygen evolution

“…ACCEPTED MANUSCRIPT 6 The above review of the literature reveals that, despite many EIS studies of porous electrodes and some EIS studies of porous IrO 2 anodes, a systematic evaluation of their EASA by reliable capacitance data is missing. The aim of this work has been the use EIS data (in their 1/(ωZ im ) vs. Z re representation) to obtain the total capacitance of IrO 2 electrocatalysts, C t , and use it to correct their overall activity towards OER for surface area effects (thus assessing their intrinsic activity).…”

“…C t can be taken as a measure of the catalyst electroactive surface area and the product R ct C t (where R ct is the OER charge transfer/polarization resistance) as the appropriate parameter to characterise the catalyst intrinsic catalytic activity. C t can also be used to correct direct current vs. electrode potential OER data for electroactive surface area effects.The electrochemical applications of iridium dioxide span a wide range, from electrochromic materials [1, 2] and pH-sensors [3,4] to supercapacitors [5][6][7][8] and oxygen evolving anodes [9][10][11][12]. Since IrO 2 electrodes show good activity and high stability for the oxygen evolution reaction (OER), they are candidates for anode components of water electrolysers and regenerative fuel cells [13][14][15][16].…”

Application of Nanocomposites for Supercapacitors: Characteristics and Properties

“…Chen et al [19] used thermal CVD to grow multi-walled CNTs on a stainless steel plate and then on top of CNTs, IrO 2 nanotubes were deposited using metal-organic CVD with the iridium source of (C 6 H 7 )(C 8 Other types of high surface area carbon materials such as activated carbons, carbon fibres and carbon aerogels were also composited with metal oxide to form high performance electroactive materials. Those examples include vapour-grown carbon fibre (VGCF) -RuO 2 xH 2 O nanocomposite prepared by a thermal decomposition [24], RuO 2 .xH 2 O-mesoporous carbon nanocomposites prepared using impregnation [25], ZnO-activated carbon nanocomposite electrode by simply mixing [26] and MoO 3 -graphite prepared by ball milling [27].…”

Efficient conversion of waste polyvinyl chloride into nanoporous carbon incorporated with MnOx exhibiting superior electrochemical performance for supercapacitor application

“…As are widely documented, carbon materials combined with transition mental oxide, such as MnO 2 [13], Fe 2 O 3 [14], IrO 2 [15], etc., can significantly improve the electrochemical performance. Among these pseudocapacitive materials, manganese oxides have been considered as a superior electrode material candidate for supercapacitor applications due to their earth-abundance, low cost, good capacitive properties, and environmental friendliness [16].…”