Exploitation of a spontaneous spatial charge separation effect in plasmonic polyhedral α-Fe2O3 nanocrystal photoelectrodes for hydrogen production

High specific surface area bipyramidal and pseudocubic polyhedral alpha-Fe2O3 nanocrystals were fabricated for hydrogen reduction in a water-splitting process. Two different facets of polyhedral alpha-Fe2O3 nanocrystals were synthesized via a versatile hydrothermal route. Typically, photocatalytic activity of hematite is limited by its relatively poor absorptivity, very short excited-state lifetime, and short hole diffusion length. To address these issues, a pseudocubic polyhedral alpha-Fe2O3 photoelectrode was fabricated that achieved a spontaneous charge spatial separation during the water-splitting process. Additionally, Sn from the FTO substrate was diffused and doped into polyhedral alpha-Fe2O3 during the sintering process to serve as an electron donor and increase the carrier density. To further exploit the surface plasmon resonance (SPR) properties and enhance the water splitting efficiency of polyhedral alpha-Fe2O3 photoelectrodes, Au nanoparticles were decorated on the surface of Fe2O3. This increased incident light absorption and suppressed charge recombination by the strong field generated from collective oscillations of surface electrons in the Au nanoparticles. Subsequently, this Au/pseudocubic Fe2O3 photoelectrode demonstrated.a 9.05 mu mol/min hydrogen production rate.