Microwave-assisted synthesis of bismuth vanadate nanoflowers decorated with gold nanoparticles with enhanced photocatalytic activity

We describe the synthesis of bismuth vanadate nanoflowers decorated with Au nanoparticles (Au-BiVO4NF) using conventional oil bath or microwave irradiation as a heating source, where de AuNPs exhibit sizes of 29 +/- 10nm and 50 +/- 11nm. We show how microwaves can be used to replace well-stablished methods in the synthesis of inorganic nanomaterials and drastically reduce both time and energy consumptions. The Au-BiVO4NF obtained under microwave irradiation exhibited the same physical-chemical properties of those prepared through conventional heating; however, time lapse for synthetizing the heterojunction decreased from 4h to only 10min. The heterojunction is a very promising photocatalyst under visible light irradiation since BiVO4 exhibits low band-gap energy and Au nanoparticles can behave as electron sinks and/or as electron sources through plasmon resonance, increasing charge separation of photogenerated electrons and holes. This synergic effect resulted in a heterojunction able to degrade similar to 95% of methylene blue after 6h of UV-visible light irradiation.