A simple post-synthesis conversion approach to Zn(OH)F and the effects of fluorine and hydroxyl on the photodegradation properties of dye wastewater

Abstract In this work, Zn(OH)F is prepared by an initiative, simple post-synthesis method, in which the molar ratio of F/Zn (R F ) was varied to investigate the effect of the NH 4 F amounts added on the samples. Further, we have mainly investigated their energy bands and photochemical properties. Under UV light irradiation (λ£420 nm), the samples (R F  = 0,1,2) show the high degradation activities of methylene blue (MB) dye, namely, 80% of MB can be degraded after 8 min. It is found that the hydroxyl and fluorine have greatly down shifted the conduction band (CB, 0.99 eV) and valence band (VB, 4.17 eV) of Zn(OH)F, compared with ZnO (CB = −0.31 eV, VB = 2.89 eV), but with the nearly same band gap. For the degradation of MB dye, the main oxidative species are holes and hydroxyl radicals for ZnO and Zn(OH)F, respectively. This study suggests that this simple post-synthesis fluorination approach could be extended to develop the other photocatalysts; moreover, we can facilely tune the band structure and photocatalytic activity by introducing or removing hydroxyl and fluorine, which could benefit to develop new photocatalysts.