CuRhO2 in the delafossite structure is a promising,
highly stable photocathode material for solar water splitting, yet
the fundamental bulk and surface properties of CuRhO2 that
are relevant to such an application have rarely been studied. In this
work, we present a comprehensive computational study of the bulk and
majority (001) surface of CuRhO2 using density functional
theory at the meta-GGA and hybrid functional levels. For bulk CuRhO2, our results show a significant degree of hybridization between
Rh, Cu, and oxygen states near the valence band maximum suggesting
a high hole mobility in this material in comparison to other Cu-delafossite
oxides. The typical Cu vacancy and Cu antisite defects are predicted
to behave as shallow acceptors in bulk CuRhO2; they do
not trap charge carriers and should not act as electron–hole
recombination centers under photoexcitation. The computed surface
stability diagram under vacuum conditions shows that CuRhO2(001) typically exposes the Rh/O termination with empty surface states
in the lower half of the band gap. Cu antisite defects can however
form on this surface, leading to deep hole states that can trap electrons
and favor the recombination of photoexcited carriers. Overall, the
present results provide fundamental insight into the properties of
intrinsic defects in the bulk and at the surface of CuRhO2. This knowledge is an essential basis for an investigation of the
photo-electrochemical performance of this material.