  Transition metal oxides have generated significant interest for their
potential as catalysts for the oxygen evolution reaction (OER) in alkaline
environments. Iron and nickel-based perovskite oxides have proven particularly
promising, with catalytic over-potentials rivaling precious metal catalysts
when the alignment of the valence band relative to the OER reaction potential
is tuned through substitutional doping or alloying. Here we report that
engineering of band alignment in LaFeO$_{3}$/LaNiO$_{3}$ (LFO/LNO)
heterostructures via interfacial doping yields greatly enhanced catalytic
performance. Using density functional theory modeling, we predict a 0.2 eV
valence band offset (VBO) between metallic LNO and semiconducting LFO that
significantly lowers the barrier for hole transport through LFO compared to the
intrinsic material and make LFO a p-type semiconductor. Experimental band
alignment measurements using in situ X-ray photoelectron spectroscopy of
epitaxial LFO/LNO heterostructures agree quite well with these predictions,
producing a measured VBO of 0.3(1) eV. OER catalytic measurements on the same
samples in alkaline solution show an increase in catalytic current density by a
factor of ~275 compared to LFO grown on n-type Nb-doped SrTiO$_{3}$. These
results demonstrate the power of tuning band alignments through interfacial
band engineering for improved catalytic
