DFT Study on the Hydrogen Evolution Reaction for Different Facets of Co2P

Co2P is one of the most promising non-noble metal catalysts for hydrogen evolution reaction (HER) during water splitting, owing to its many advantages, such as earth-abundance, high activity and good stability. The as-synthesized Co2P is multi-faceted while its facet-dependent HER activity is still little known. To explore the facet-dependent HER activity of Co2P, density functional theory (DFT) calculations are conducted for five different facets of Co2P: (001), (010), (101), (112) and (113) in this work. By comparing the surface energy and Gibbs free energy of H* (Delta G(H*)) of these five facets, Co2P (113) is found to possess both good surface stability and high HER activity, which could be the guidance for catalyst design and synthesis. Multiple linear regression has been adopted to quantitatively scrutinize the relationship between H-Co bond length distribution and Delta G(H*), and the mean absolute error of the multiple linear regression is as small as 0.0756 eV. This analysis shows that statistical methods are effective to explore the effect of structure on the HER activity, which could be helpful in understanding the underlying HER mechanism.