Graphene oxide-TiO2 and reduced graphene oxide-TiO2 nanocomposites: Insight in charge-carrier lifetime measurements

Abstract

A hybrid nanocomposites containing nanocrystalline TiO2 and graphene related materials (graphene oxide and reduced graphene oxide) were successfully prepared elevated pressure using hydrothermal method. The structural and textural properties as well as the presence of different carbonaceous structures on the surface of obtained nanocomposites have been characterized by means of XRD, FTIR/DRS and Raman spectroscopy. FTIR/DRS analysis allowed to find characteristic peaks of graphene oxide: epoxy stretching at 1229cm−1 and alkoxy stretching vibration at 1059cm−1. In the spectrum of nanocomposites containing rGO, all the bands decreased or even disappear. It can be indicated that GO was successfully reduced to rGO. SEM studies showed difference between graphene oxide (aggregated, crumpled, non-transparent) and reduced graphene oxide (thin and transparent) flakes. The Time Resolved Microwave Conductivity analysis have been utilized to investigate the excess of charge-carrier lifetimes in TiO2-graphene oxide and TiO2-reduced graphene oxide hybrid nanocomposites. It was generally concluded that modification of starting TiO2 with carbonaceous precursors leads to the slight increase of intensity of the TRMC signals, indicating that more electrons are induced in the conduction band of hybrid nanocomposites. It is also worth mentioning that the decay of studied signals of modified powders depends on added carbon precursor, indicating that the type of deposited species may affect the slight or significant suppression of recombination or charge-carriers trapping.