Preparation and Electrochemical Performance of CNT Electrode with Deposited Titanium Dioxide for Electrochemical Capacitor

Abstract

To reduce polarization of electrochemical capacitor based on carbon nanotube, titanium oxide nanoparticles were deposited by ultrasound. The pore distribution of TiO2/CNT nanoparticle exhibited surface area of 341 m 2 g -1 when TiO2 content was 4 wt %, which was better than that of pristine CNT with surface area of 188 m 2 g -1 . The analyses indicated that titanium oxide (particle diameter < 20 nm) was deposited on the CNT surface. The electrochemical performance was evaluated by using cyclic voltammetry (CV), impedance measurement, and constant-current charge/discharge cycling techniques. The TiO2/CNT composite electrode showed relatively better electrochemical behaviors than CNT electrode by increasing the specific capacitance from 22 Fg -1 to 37 Fg -1 in 1 M H2SO4 solution. A symmetric cell assembled with the composite electrodes showed the specific capacitance value of 11 Fg -1 at a current loading of 0.5 mAcm -2 during initial cycling.

Metal‐organic chemical vapor deposition of anatase titania on multiwalled carbon nanotubes for electrochemical capacitors

“…This could be because surface-controlled reactions induced by TiO 2 in electrodes increased as scan speed was raised. 56 Additionally, at 10 mV s −1 , the current work is in agreement with the work reported by Kim et al 30 (involving 4, 6, 17, and 33 wt.% of TiO 2 ) in that C s declines with an increase in TiO 2 wt.% in TiO 2 -MWCNT (Figure 6F). However, the current work varied from this trend at higher scan rates (100 and 200 mV s −1 ) in that the 20 wt.% TiO 2 TiO 2 -MWCNT material displayed a 5000-fold improvement of C s relative to that of 5 wt.% (Figure 6F and Supporting Information: Table S1).…”

“…However, it was slightly lowered by an increase in TiO 2 wt.% (insert in Figure 7), and this corroborated with other TiO 2 composites synthesized by the sol‐gel method 2,14 . Hence, the slight ESR variations can conceivably be regarded as negligible to the relative capacitive differences in the current composites 30 …”

“…This was ascribed to the bundling of the coated MWCNTs. A similar decline in BET surface areas was also reported for composites synthesized by the sol‐gel method 30 . Despite this clear inversely proportional effect as regards porosity and BET surface area, the pore sizes were smallest for the 10 wt.% TiO 2 material.…”

“…2,14 Hence, the slight ESR variations can conceivably be regarded as negligible to the relative capacitive differences in the current composites. 30…”

“…The same authors also reported a wet impregnation synthesis method, followed by microwave deposition of TiO 2 from tetrabutyl titanate onto MWCNTs, which improved C s by 1.37-fold in H 2 SO 4 electrolyte. 13 Kim et al 30 synthesized TiO 2 -MWCNT composites by a sol-gel method from titanium isopropoxide that enhanced the C s 1.68-fold also in the H 2 SO 4 electrolyte. Krishnaveni and Anandan 42 also reported unzipped MWCNTs in TiO 2 -MWCNT through an ultrasound-assisted method for EC applications in Na 2 SO 4 that achieved an 8.54-fold enhancement.…”