The phase stability of InP(001) surfaces upon oxygen exposure from first principles

III-V semiconductors such as indium phosphide and multinary alloys derived thereof have shown high performance in multi-junction photoelectrochemical devices for solar water splitting. However, electrochemical conditions, especially in aqueous electrolytes, often lead to changes in surface structure and stoichiometry. These changes then affect the electronic structure, for instance leading to the formation of charge-carrier recombination centers or points of attack for dissolution of the material. It is therefore important to understand the surface structures that may arise in electrochemical environments to identify routes for electronic and electrochemical surface passivation. In this work, we assess the impact of oxygen adsorption on surface reconstructions of InP(001) <i>via</i> first principle calculations. We observe predominantly P-rich surfaces for a large range of indium and oxygen chemical potentials, showing P _<i>x</i> O _<i>y</i> -type polyphosphate motifs. On the other hand, the frequently assumed In-rich (2 × 4) mixed-dimer surface reconstruction is found to be unstable for a large range of oxygen chemical potentials.