Synthesis, characterisation and photocatalytic activity of N-doped TiO2–Nb2O5 mixed oxides

• Nitrogen-doped TiO2/Nb2O5 photocatalysts were synthesised and characterised.
• Nitrogen doping reduced the band gap energy by 12%.
• Benzene, toluene and xylene solutions were 65% degraded with N-doped TiO2/Nb2O5 in 150 min.

Nitrogen-doped TiO2 and TiO2–Nb2O5 catalysts were prepared by sol–gel technique using titanium isopropoxide (TIP) and potassium niobate. The obtained samples were subsequently calcined at 380 and 500 °C. Undoped TiO2 and TiO2–Nb2O5 samples were also prepared by way of comparison. The photocatalytic activities of the synthesised catalysts were evaluated on the photodegradation of benzene, toluene and xylenes (BTX) solution under UVA and visible light. The level of nitrogen incorporated on N-doped TiO2–Nb2O5 catalyst was found to be 0.49 at%. Concentrations of BTX were analysed by gas chromatography applying the headspace technique. The N-doped TiO2–Nb2O5 catalyst calcined at 500 °C led to reductions of benzene, toluene and xylenes greater than 65 wt% after 150 min of irradiation. The photocatalytic reactions followed the first order kinetics.

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