Decomposition of 2-naphthol in water and antibacterial property by NiO and CeO_x modified TiO₂ in the dark or under visible light

Abstract

Rutile-type TiO₂ was modified with NiO and CeO_x using chemisorption calcination cycle method. Then the decomposition activity of 2-naphthol in water was evaluated in the dark or under visible light at 50°C. Little difference was found in the specific surface area or crystal phase before and after modification. The NiO modification decreased the apparent bandgap and provided photocatalytic decomposition activity under visible light. Results suggest that the formation of a Ti–O–Ni interfacial bond yielding a surface d sub-band plays an important role in this increased activity. Although the NiO-modified TiO₂ possessed decomposition activity only under visible light, additional modification of CeO_x onto the material enabled decomposition of 2-naphthol in water in the dark at 50°C. The dark activity was attributed to the Mars–van Krevelen mechanism of Ce in CeO_x. The NiO-modified TiO₂ exhibited high antibacterial activity against Escherichia coli and Staphylococcus aureus under visible light at room temperature.