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

A new insight into photoinduced charge transfer processes across carbon nanotube@TiO 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 TiO results in hole-doped oxMWCNTs and reduced TiO. The latter is inferred from femto- and nanosecond transient absorption spectroscopy performed with oxMWCNT@TiO 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 TiO in these hybrids.