Very low amount of TiO2 on N-doped carbon nanotubes significantly improves oxygen reduction activity and stability of supported Pt nanoparticles

Abstract

Electrochemical corrosion is a major problem for carbon materials used in electrocatalysis. Highly dispersed TiO₂ was deposited on O-functionalized and N-doped carbon nanotubes by chemical vapour deposition to tackle the carbon corrosion problem. Very low Ti loadings of about 1 wt% were applied to minimize the negative influence of TiO₂ as a semiconductor on the high conductivity of carbon materials. Both N doping and TiO₂ coating facilitate strong metal–support interactions and favour the formation of small Pt particles. N doping improved the intrinsic catalytic activity of the carbon support and enhanced the conductivity due to the removal of surface oxygen groups, while the negative effect of TiO₂ on conductivity is counterbalanced by its promoting effect on metal–support interactions leading to enhanced overall catalytic performance. Pt/TiO₂/NCNTs showed the highest ORR activity, and significantly outperformed Pt/NCNTs in electrochemical stability tests.