Oxygen reduction characteristics of bamboo-shaped, multi-walled carbon nanotubes without nitrogen in acid media

The oxygen reduction characteristics of bamboo-shaped multi-walled carbon nanotubes (BCNTs) were compared with those of hollow-shaped multi-walled carbon nanotubes (HCNTs) Structural and compositional differences between HCNTs and BCNTs were assessed using TEM BET TDS Raman TG-DTA and XPS measurements A rotating disk electrode was used to study the influence of their structure on the activity of the oxygen reduction reaction (ORR) It was found that BCNTs showed higher catalytic activity in the ORR compared with HCNTs regardless of whether the BCNTs were untreated or acid-treated The onset potential for the ORR was 0 66 V (vs RHE) for acid-treated BCNTs 0 32 V higher than that of acid-treated HCNTs In addition It was confirmed that the reduction current normalized by the BET surface area at a potential of -0 1 V (vs RHE) was approximately 2 2 times higher for acid-treated BCNTs Collectively the results indicate that a disordered surface with pentagonal defects rounded compartments and edge plane sites contribute to the superior ORR characteristics of BCNTs (C) 2010 Elsevier Ltd All rights reserved