Achieving maximum photo-oxidation reactivity of Cs0.68Ti1.83O4-xNx photocatalysts through valence band fine-tuning

Does a wider absorption range of the photocatalyst always result in a higher photoreactivity? By investigating a set of Cs0.68Ti1.83O4-xNx (x = 0-0.31) photocatalysts with a continuously tuned absorption edge, we found that although the absorption edge of Cs0.68Ti1.83O4-xNx is gradually shifted to the low-energy region with the increase of the nitrogen dopant, the photoreactivity of the photocatalyst in terms of generating the-OH radical does not correspondingly increase under the irradiation of monochromatic light of 254 nm and continuous spectrum of > 300 nm. The fundamental mechanism of the anion dopant enhanced photocatalytic activity through the interplay of three key factors-absorbance, oxidative potential and mobility of charge carriers-is proposed to explain the observed photocatalytic activity change.