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.