Evaluation of the simulated solar light photocatalytic activity of N, Ir co-doped TiO2 for organic dye removal from water

• Published in: Applied surface science 2015-02, Vol.329, p.127-136
• Main Authors: Kuvarega, Alex T., Krause, Rui W.M., Mamba, Bhekie B.
• Format: Article
• Language: English
• Subjects: Band gap; Co-doping; Correlation; Degradation; Dyes; Energy gaps (solid state); Photocatalysis; Platinum group metal; Rate constants; Rutile; Titanium dioxide; Transmission electron microscopy; Visible light
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.12.089

•One pot fabrication of N, Ir co-doped TiO2.•Amorphous and rutile forms of IrO2 were detected.•High photoactivity was observed for the 0.4% Ir, N co-doped TiO2.•Amount of Ir had an impact on the photoactivity of the materials. The photocatalytic degradation of eosin yellow over N, Ir co-doped TiO2 was studied over an Ir loading concentration range of 0–1%. The synthesised materials were characterised by FTIR, Raman spectroscopy, XRD, DRUV–vis, SEM, EDS and TEM. All the samples existed mainly in the anatase phase except for the N, Ir TiO2 (1.0% Ir) which showed presence of some rutile phase. There was a gradual decrease in band gaps with increasing amount of Ir in all the samples which did not correlate with the visible light photoactivity. The materials consisted of nearly spherical particles of 20–30nm in size. The photodegradation kinetic data were explained using the Langmuir–Hinshelwood model with most of the samples giving best fit in the first 90min of the experiment. Initial rate constants were a function of Ir loadings as well as the phase composition of the samples. The N doped TiO2 showed superior photoactivity with near complete dye degradation (99.6%) being realised in about 150min. The N, Ir TiO (0.8% Ir) was the least effective.