Only few researches have devoted to correlate the P–N junction
powder photocatalysts to the electrical voltammetry so as to
substantiate the existence and the functionality of P–N junction. The
NiO/TiO
photocatalyst is a P–N junction photocatalyst because NiO is
reported to be a p-type semiconductor [12–14], and TiO
2
is a wellknown
n-type material. In this study, we focus on improving the
electron and hole separation of TiO
by impregnating NiO, which has
also been reported to have photocatalytic activity [13,15], onto selfprepared
TiO