Single-crystalline (FexNi1-x)2P nanosheets with dominant { 01 1 ¯ 1 ¯ } facets: Efficient electrocatalysts for hydrogen evolution reaction at all pH values

Abstract Electrocatalytic hydrogen evolution reaction (HER) plays a critical role in developing hydrogen and fuel cell technologies. At present, only platinum (Pt) and its compounds are thought to be efficient electrocatalysts for HER, particularly at all-pH values. However, the scarcity and high cost of Pt-based catalysts have seriously hindered their practical application in HER. Here, we report a two-step method for synthesizing single-crystalline (FexNi1-x)2P nanosheets with exposed { 01 1 ¯ 1 ¯ } facets on Ni foam. Compared with pristine Ni2P, the (FexNi1-x)2P nanosheets exhibit a dramatically improved HER activity (an overpotential of 81, 90, 103 mV at 10 mA cm−2 in acidic, neutral and alkaline media, respectively). Based on the density functional theory (DFT) calculations, it is observed that trace Fe-doping can lead to more charge accumulation around P active sites, which accordingly decreases the ΔGH* and ΔGH2O and promotes the catalytic activity.