Interfacial charge transfer in functionalized multi-walled carbon nanotube@TiO2 nanofibres

Abstract

A new insight into photoinduced charge transfer processes across carbon nanotube@TiO₂ interfaces has been gained based on experimental details from transient absorption spectroscopy. We show that photoinduced, interfacial hole transfer to carboxylic acid-functionalized multiwalled carbon nanotubes (oxMWCNTs) from TiO₂ results in hole-doped oxMWCNTs and reduced TiO₂. The latter is inferred from femto- and nanosecond transient absorption spectroscopy performed with oxMWCNT@TiO₂ dispersions and complemented with investigations using methyl viologen and N,N,N′,N′-tetramethyl-p-phenylenediamine as an electron scavenger and a hole scavenger, respectively. The results of ultraviolet photoemission spectroscopy (UPS) of the compounds corroborate the findings, highlighting the strong coupling between oxMWCNTs and TiO₂ in these hybrids.