Facile ion-exchange synthesis of visible light active Sn-doped defect pyrochlore K0.51Sb2.67O6.26 and study of its photocatalytic activity

BACKGROUNDSn-doped metal oxides have attracted considerable attention due to their potential applications in environmental remediation by degrading organic pollutants to less harmful byproducts and hydrogen generation from water splitting. Divalent tin was doped into defect pyrochlore K0.51Sb2.67O6.26 (KSO) to improve its visible light photocatalytic activity. RESULTSThe Sn-doped K0.51Sb2.67O6.26 (SSO) was obtained from parent KSO by an ion exchange method. The bandgap energy of KSO was reduced from 3.64 to 2.68 eV following Sn2+ doping into the KSO latttice. The photocatalytic activity of KSO and SSO was studied by degradation of methylene blue (MB) and rhodamine B (RhB) under visible light irradiation. SSO showed higher photodegrdation of MB and RhB whereas pristine KSO was almost inactive for the degradation of both dyes. CONCLUSIONSThe MB and RhB degradation efficiency of SSO was 86 and 53%, respectively. The higher photocatalytic activity of SSO is attributed to more absorption of light energy in the visible region due to lowering of the bandgap energy as well as the generation of (OH)-O-center dot radicals during the photocatalytic reaction. Even after a fourth cycle of photodegradation of MB, the photocatalyst (SSO) was found to be stable, with a marginal decrease in the rate of degradation. (c) 2013 Society of Chemical Industry