Heterojunction Fe2O3-SnO2 Nanostructured Photoanode for Efficient Photoelectrochemical Water Splitting

Hierarchically organized nanostructures were fabricated by growing SnO₂ nanoparticles on a fluorine-doped tin oxide/glass substrate via a laser ablation method. Cauliflower-like clusters consisting of agglomerated nanoparticles were deposited and aligned with respect to the substrate with a large internal surface area and open channels of pores. The morphological changes of SnO₂ nanostructured films were investigated as a function of the oxygen working pressure in the range of 100-500 mTorr. A nanostructured scaffold prepared at an oxygen working pressure of 100 mTorr exhibited the best photoelectrochemical (PEC) performance. A Ti:Fe₂O₃-SnO₂ nanostructured photoanode showed the photocurrent that was 34% larger than that of a Ti:Fe₂O₃ flat photoanode when the amount of Ti:Fe₂O₃ sensitizer was identical for the two photoanodes. The larger surface area and longer electron lifetime of the Ti:Fe₂O₃-SnO₂ nanostructured photoanode explains its improved PEC performance.