DFT studies of bulk and surfaces of the electrocatalyst cobalt phosphide CoP2

CoP2 is a promising electro-catalyst for the oxygen evolution reaction from water. We have carried out a DFT study of its bulk properties and low-index surfaces. CoP2 is found to be diamagnetic with a bandgap energy between 0.4 and 0.8 eV, depending on the functional used (PBE, HSE06 and B3LYP). The (1 0 0) and (0 0 1) facets are found to be the most stable (surface energy (Es) close to 0.1 eV/Å2 and work function (ϕ) = 5.2 and 5.0 eV, respectively) while the (0 1 0) facet is the least. A reasonable inverse linear relationship between Es and ϕ is extracted for the seven surfaces investigated.