Sonochemical synthesis of nanospherical TiO₂ within graphene oxide nanosheets and its application as a photocatalyst and a Schottky diode

The hybrid of graphene oxide (GO) nanosheets with well embedded nanospherical TiO2 was prepared through mechanical mixing using ultrasound. This modified TiO2-GO (TGO) composite exhibits reduced recombination of charge carriers. Benefiting from unique morphology and surface area (92 m(2)g(-1)), the TGO composite showed remarkable catalytic activity for the photodegradation of congo red (CR) and methyl orange (MO). The rate constant values were 0.0652 min(-1) (pseudo first order) for CR (5 ppm) and 0.0631 min(-1) for MO (5 ppm). The stability and aggregation behavior of TGO was examined using the dynamic light scattering (DLS) technique. The key parameter affecting photocatalytic performance is electron-hole separation. To illustrate this issue, a Schottky diode has been fabricated with TGO composite, in contact with aluminium. Important diode parameters i.e. ideality factor, series resistance, barrier height have been estimated from forward current-voltage (IV) characteristics. Space charge limited current (SCLC) theory was employed to provide insight into the carrier transport properties of TGO and enhanced carrier mobility (2.11.10(-6) m(2) v(-1) s(-1)) and low transit time (0.237.10(-6) s) under illumination was obtained. The composite appears suitable for energy and photocatalytic applications.