Simultaneous reduction of surface, bulk, and interface recombination for Au nanoparticle-embedded hematite nanorod photoanodes toward efficient water splitting

Abstract

Solar water splitting has received increasing attention as a very promising strategy to produce clean hydrogen fuels. This work presents a novel design consisting of an Au-embedded Fe₂O₃ nanorod (NR) structures on an iron substrate as the photoanode, and demonstrates the effects of Au nanoparticles in the bulk and interface layers, and self-cocatalyst treatment for solar water splitting. A synergistic effect of the Au nanoparticles and oxygen vacancies on the Fe₂O₃ NRs allows the electrons and holes to have relatively high mobility for suppressing charge recombination. The metallic nature of the Au layer located at the interface between NRs and the compact oxide layer results in more efficient electron transfer from NRs to the back side. The crystalline-core/amorphous-shell structure further facilitates the transfer of holes to the electrode/electrolyte interface for oxidation reaction. Upon the configuration established, a higher photocurrent with a low onset potential is achieved for the Au/Fe₂O₃ NRs photoanode under AM 1.5G illumination. The improved photoelectrochemical performance is ascribed to improved light harvesting, increased charge carrier density, and suppressed charge recombination at the hematite/electrolyte and hematite/substrate interfaces. Most importantly, such a facile approach can simultaneously reduce the surface, bulk, and interface recombination characteristic of hematite photoanodes grown on iron substrates.