In-situ growth of iron/nickel phosphides hybrid on nickel foam as bifunctional electrocatalyst for overall water splitting

The use of nonprecious metal-based materials as bifunctional electrocatalysts for overall water splitting is of great significance to design and utilize cost-efficient commercial clean energy devices. Herein we report a facile method for the in-situ growth of iron/nickel phosphides hybrid on nickel foam via direct phosphorization of nickel foam after treated by iron nitrate aqueous solution. The optimal sample exhibits superior hydrogen and oxygen evolution reaction activities with low overpotentials of 63 and 185 mV at 10 mA cm−2 and small Tafel slopes of 59 and 47 mV dec−1 in 1 M KOH, respectively. The corresponding two-electrode cell demands 1.567 V to achieve 10 mA cm−2 without iR compensation. It can deliver a large current density of around 113 mA cm−2 without decay during the electrolysis at 2 V for 24 h. The morphological, structural and component evolution of the as-prepared iron/nickel phosphides hybrid are systematically investigated. The synergistic effect between Ni2P and FeP and the formation of three-dimensional iron and nickel (oxy)hydroxides as real catalytic active sites play an important role in significantly improving the electrocatalytic activity. This work provides a further insight into the nickel foam-based bifunctional electrocatalysts for overall water splitting.