Microwave-assisted hydrothermal synthesis and electrochemical characterization of niobium pentoxide/carbon nanotubes com
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Microwave-assisted hydrothermal synthesis and electrochemical characterization of niobium pentoxide/ carbon nanotubes composites Ricardo M. Silva1, Bruno S. Noremberg2, Natália H. Marins1, Jordan Milne3, Igor Zhitomirsky3, Neftalí L.V. Carreño2,a) 1 Materials Science and Engineering, Federal University of Pelotas, RS 96010-610, Brazil; and Materials Science and Engineering, McMaster University, Hamilton, ON L8S 4L8, Canada 2 Materials Science and Engineering, Federal University of Pelotas, Pelotas - RS 96010-610, Brazil 3 Materials Science and Engineering, McMaster University, Hamilton, ON L8S 4L8, Canada a) Address all correspondence to this author. e-mail: [email protected]
Received: 12 September 2018; accepted: 31 October 2018
This study reports the fabrication of high mass loading (32 mg/cm2) electrodes of niobium pentoxide (Nb2O5) nanoparticles and carbon nanotubes (CNTs) using a facile procedure. The as-obtained Nb2O5 nanoparticles by microwave-assisted hydrothermal synthesis presented pseudohexagonal (TT) phase, and when exposed to the thermal treatment, the Nb2O5 nanoparticles changed to orthorhombic (T) phase. Distinct morphologies were obtained, which exhibited a specific surface area of 216 m2/g and 47 m2/g to pseudohexagonal and orthorhombic phases, respectively. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were performed in a three-electrode system using 1 M Li2SO4 as electrolyte with a potential window of 0–0.9 V (versus standard calomel electrode). Both materials showed capacitive behavior with a specific capacitance of 0.11 F/cm2 and 0.09 F/cm2 to nanocomposites CNT 1 TT-Nb2O5 and CNT 1 T-Nb2O5 at 2 mV/s, respectively. Thus, an efficient, simple, and promising process to produce electrodes for supercapacitors was demonstrated.
Introduction In the last few years, a variety of energy-storage device applications have expanded from compact electronics to large-scale energy storage systems, including renewable energy storage and electric transportation [1, 2]. To accomplish the energy and power density requirements for energy applications, many researchers have given attention to the synthesis of oxide-based nanomaterials because of their chemical, physical, optical, and electronic properties [1, 2, 3, 4]. Another concern is to investigate nontoxic and abundant materials to lower the costs and increase device safety in both consumer products and in stationary power [2]. In this way, niobium pentoxide (Nb2O5) is a promising material because of its particular properties such as a ;3.4 eV band gap, low toxicity, surface acidity, and good chemical and thermal stabilities [3, 5, 6, 7], It has been demonstrated that Nb2O5 can deliver a high power through a mainly pseudocapacitive reaction of Li-ion (Li1), which could happen not only at the surface but also in the bulk
ª Materials Research Society 2019
of the Nb2O5 in nonaqueous Li1 electrolyte [2, 8]. The intercalation pseudocapacitive depends on factors such as crystalline structure and specific surface area. Materials with hig
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