Characterization of TiO2-based semiconductors for photocatalysis by electrochemical impedance spectroscopy

• Published in: Applied surface science 2016-11, Vol.387, p.183-189
• Main Authors: Ângelo, Joana, Magalhães, Pedro, Andrade, Luísa, Mendes, Adélio
• Format: Article
• Language: English
• Subjects: Charge transfer; Conversion; Electrochemical impedance spectroscopy; Graphene; Photocatalysis; Photocatalysts; Photoelectrochemical; Pollutants degradation; Semiconductors; Titanium dioxide
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.06.101

[Display omitted] •P25/graphene composite presents the highest photocatalytic activity.•P25/graphene composite photocatalyst exhibited lower values of RCT and CSC.•Composite enhances charge mobility, decreasing the probability of recombination.•EIS is a suitable technique to characterize photocatalysts. The photocatalytic activity of a commercial titanium dioxide (P25) and of an in-house prepared P25/graphene composite is assessed according to standard ISO 22197-1:2007. The photoactivity performances of bare and composite TiO2-based materials were further studied by electrochemical impedance spectroscopy (EIS) technique to better understand the function of the graphene in the composite. EIS experiments were performed using a three-electrode configuration, which allows obtaining more detailed information about the complex charge transfer phenomena at the semiconductor/electrolyte interface. The Randles equivalent circuit was selected as the most suitable for modelling the present photocatalysts. The use of the graphene composite allows a more effective charge separation with lower charge transfer resistance and less e−/h+ recombination on the composite photocatalyst, reflected in the higher values of NO conversion.