Highly stable sub-5 nm Sn6O4(OH)4 nanocrystals with ultrahigh activity as advanced photocatalytic materials for photodegradation of methyl orange

Among numerous active photocatalytic materials, Sn-based oxide nanomaterials are promising photocatalytic materials in environmental protection measures such as water remediation due to their excellent physicochemical property. Research on photocatalytic nanomaterials for photodegradation of methyl orange (MO) so far has focused on TiO2-based nanostructures; e. g., TiO2-P25 is recognized to be the best commercial photocatalyst to date, rather than Sn-based oxide nanomaterials, in spite of their impressive acid-and alkali-resistant properties and high stability. Here, we demonstrate very high photocatalytic activity of highly stable sub-5 nm hydromarchite (Sn6O4(OH)(4)) nanocrystals synthesized by a simple and environmentally friendly laser-based technique. These Sn6O4(OH)(4) nanocrystals exhibit ultrahigh photocatalytic performance for photodegradation of MO and their degradation efficiency is far superior to that of TiO2-P25. The detailed investigations demonstrated that the great photocatalytic activity results from the ultrafine size and unique surface activity induced by the laser-based technique. Mass production of reactive species of hydroxyl radicals was detected in the experiments due to the appropriate bandgap of Sn6O4(OH)(4) nanocrystals. These findings actually open a door to applications of Sn-based oxide nanomaterials as advanced photocatalytic materials.