Effect of structural defects towards the performance of TiO2/SnO2/WO3 photocatalyst in the degradation of 1,2-dichlorobenzene

• New trimetallic oxides with exposed facets have been prepared from sol–gel and hydrothermal method.
• Comparison of the photocatalytic activity done under UV and visible light showed that TiO2/SnO2/WO3 catalyst is active at visible light.
• The presence of Ti3+ on the surface of hydrothermal prepared catalyst showed better activity compared to sol–gel prepared catalyst with exposed facets only.
• Enhanced photocatalytic activity was observed due to the charge transfer and suppressed recombination of electron–hole which was confirmed from XPS and PL.

In this study, the effect of surface/structural defects of TiO2/SnO2/WO3 trimetallic oxide on the photocatalytic activity was investigated. Two sets of trimetallic oxide were prepared by mechanical mixing of the pure TiO2, WO3 and SnO2 with exposed facets synthesized by sol–gel and hydrothermal methods. These photocatalysts were characterized by XRD, DRUV, PL, FESEM, TEM and XPS. Comparison of the photocatalytic degradation of 1,2-dichlorobenzene was done under UV and visible light. The results showed that the trimetallic oxide prepared from hydrothermal exhibited higher photocatalytic activity under visible light compared to the sol–gel prepared photocatalyst. Based on the characterization, it could be deduced that the high photocatalytic activity was attributed to the synergistic effect of several factors such as the exposed facets, presence of Ti3+ and charge transfer (revealed by XPS) between the metal oxides through the heterojunction (from TEM image) formation. The charge transfer was further projected through a schematic diagram that showed the potential energy differences at the valence band and conduction band of the metal oxides.

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