FeP3 monolayer as a high-efficiency catalyst for hydrogen evolution reaction

An urgent and key problem in hydrogen evolution reaction (HER) is to prepare low-cost catalysts with activity comparable to that of platinum (Pt), an intrinsic large number of active sites, and high electrical conductivity. Two-dimensional materials as HER catalysts demonstrate unique advantages. Here, we make first-principles swarm-intelligence structure search calculations to identify a hitherto unknown FeP3 monolayer with a number of desirable properties. The FeP3 monolayer shows metallicity and has a high density of states at the Fermi level, showing excellent electrical conductivity. Its HER activity is comparable to that of Pt in view of its low hydrogen adsorption Gibbs free energy and large number of active sites, originating from the more exposed and negatively charged P atoms. More interestingly, the FeP3 monolayer maintains high HER activity under a biaxial strain of 4%. All these appealing properties make the predicted FeP3 monolayer a promising candidate for application in HER. Moreover, the relationship between HER activity and P content in FePx (x = 1–4) monolayers is explored, providing useful information for designing HER catalysts.