Spontaneous reduction of Pt(IV) onto the sidewalls of functionalized multiwalled carbon nanotubes as catalysts for oxygen reduction reaction in PEMFCs

This paper reports spontaneous formation of metal nanoparticles on the sidewalls of the functionalized MCNTs (FMCNTs) when the FMCNTs were immersed in corresponding metal salt solutions. At first, MCNTs were functionalized by oxidation of a mixture consisting of H2SO4/HNO3 or H2SO4/HNO2 and formed oxygen-containing functional groups such as -COOH, -OH, etc., by which the metal ions (pt(4+)) were reduced on the sidewalls of FMCNTs. No other substance that is suspicious of being a reducer was introduced in the pt(4+) ion reduction. The properties of FMCNTs and platinized FMCNTs were characterized electrochemically and instrumentally. The results showed that the electrode made from platinized FMCNTs with Pt loading of 0.12 mg cm(-2) had enhanced catalytic activity for the oxygen reduction reaction over one made from commercial Pt/C catalyst with Pt loading of 0.27 mg cm(-1).