Solar H2 generation via ethanol photoreforming on ε-Fe2O3 nanorod arrays activated by Ag and Au nanoparticles

Abstract

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 ε-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 ε-Fe₂O₃ enabled to obtain a significant H₂ production even under sole Vis light.