P–N junction mechanism on improved NiO/TiO2 photocatalyst

The composite photocatalyst comprising p-type NiO and n-type TiO2 showed improved photoactivity due to the inhibition of electron–hole recombination. A series of P–N junction photocatalysts, NiO/TiO2, were prepared by incipient wetness impregnation. The photocatalysts were characterized by UV–vis spectroscopy, XRD and XPS. The photoactivity of photocatalysts was tested by the degradation of methylene blue. The results showed that 0.5 wt.% NiO/TiO2 had the highest activity as compared with TiO2. A P–N junction mechanism was proposed and verified that the photocurrent could be enhanced under forward bias in the NiO/TiO2 film. The photoactivity enhancement is attributed to P–N junction and co-catalyst effects.

Graphic abstractThe composite photocatalyst of p-type NiO and n-type TiO2 improves photoactivity due to the inhibition of electron–hole recombination. A P–N junction mechanism is verified by increasing photocurrent under forward bias. The enhanced activity is attributed to P–N junction of NiO/TiO2.Figure optionsDownload as PowerPoint slideResearch Highlights
► The P–N junction of photocatalyst was studied by the photocurrents using voltammetry.
► The electron–hole recombination is retarded by the P–N junction of NiO/TiO2.
► Combination of p-type NiO and n-type TiO2 can improve photocatalytic activity.