Modulation of Photogenerated Carrier Transport by Integration of Sb₂O₃ with Fe₂O₃ for Improved Photoelectrochemical Water Oxidation

Optimization of photogenerated carrier transport by heterojunction engineering has been realized as an effective strategy to improve the electrode performance in photoelectrochemical (PEC) systems. We report for the first time a type II heterostructure consisting of Sb2O3 and Fe2O3 for significantly enhanced PEC water oxidation. The as-fabricated photoanode exhibits prominent performance with a photocurrent density as high as 1.31 mA cm–2 at 1.23 V (vs. reversible hydrogen electrode), 14.5 times that of bare Fe2O3, as well as remarkable applied bias photon-to-current efficiency (10.7 times that of Fe2O3) and long-term stability (over 20 h). Notably, it outperforms all the Sb2O3-based photoanodes reported to date. The excellent PEC performance is ascribed to the rational integration of the matched merits of different components, i.e., interleaved step energy bands and complementary band gaps of Sb2O3 and Fe2O3. Along with the enhanced electrical conductivity, the photogenerated carriers are capable of flowing to the desired direction at a fast migration rate for participating in redox reactions on the electrode surface, and the electron–hole recombination is simultaneously efficiently inhibited.