TiO₂−Multiwalled Carbon Nanotube Heterojunction Arrays and Their Charge Separation Capability

Abstract

Aligned multiwalled carbon nanotubes (MWNTs) coated with TiO 2 nanoparticles were fabricated on a titanium foil by atmospheric pressure chemical vapor deposition (CVD). Their morphology was characterized by environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM). The results revealed MWNTs were aligned, and each MWNT with well-graphited walls was coated with TiO 2 nanoparticles. Measured by a micromanipulator manual probe station, the current−voltage ( I − V ) curve of aligned MWNTs on the titanium substrate (MWNT/Ti) was almost linear due to ohmic MWNT−Ti contacts, whereas for aligned MWNTs coated with TiO 2 nanoparticles on titanium substrate (TiO 2 −MWNT/Ti), the I − V curve revealed rectifying behavior, and this rectification demonstrated that a heterojunction had been formed between TiO 2 and the MWNT. The photoelectrochemical investigations certified that the TiO 2 −MWNT heterojunction could minimize recombination of photoinduced electrons and holes and had a more effective photoconversion capability than the aligned TiO 2 nanotubes on the titanium substrate (TiO 2 /Ti).