Solar H-2 generation via ethanol photoreforming on epsilon-Fe2O3 nanorod arrays activated by Ag and Au nanoparticles

Earth-abundant, non toxic and cheap Fe2O3 can be used as photocatalyst for sustainable hydrogen production from bio-ethanol aqueous solutions, under sunlight irradiation and without the application of any external electrical bias. To this aim, supported materials are not only technologically more appealing than powders, but also of key importance to develop photoactive and stable Fe2O3-based nanostructured photocatalysts. Here we demonstrated that, while bulk Fe2O3 is unsuitable for solar hydrogen evolution, nanostructured iron(III) oxide polymorphs show promising photoactivity. In particular, a hydrogen yield of 20 mmol h(-1) m(-2) was obtained on epsilon-Fe2O3 nanorod arrays supported on Si(100) under simulated sunlight irradiation, mainly due to UV solar photon absorption. The functionalization with partially oxidized Ag nanoparticles resulted in a positive performance improvement upon selective irradiation with the UV portion of the solar spectrum. Conversely, the incorporation of Au nanoaggregates into epsilon-Fe2O3 enabled to obtain a significant H-2 production even under sole Vis light.