One-step in-situ sprouting high-performance NiCoSxSey bifunctional catalysts for water electrolysis at low cell voltages and high current densities

Engineering high-performance non-precious metal-based bifunctional catalysts for water splitting are still facing some issues especially at industry-relevant current densities. Here, this challenge is addressed by the new approach to grow extra-stable nickel cobalt sulfur-selenide (NiCoS x Se y ) nanosheet catalysts on nickel–cobalt foam (NCF), and the obtained NiCoS x Se y affords the low overpotentials of 345 mV for hydrogen evolution reaction (HER) and 427 mV for oxygen evolution reaction (OER) at 1000 mA cm −2 ( j 1000 ). Meanwhile, the NiCoS x Se y /NCF also shows the excellent long-term stability for both HER and OER processes driven with j 100 for 100 h and j 500 for 24 h. In addition, the cell voltage assembled with NiCoS x Se y /NCF is only 1.84 V at j 500 in 1 M KOH, and the I-t characteristic shows a low decay (<3 %) after 50 h operation at j 100 . The ab-initio simulations reveal that the CoS 2 -CoSe 2 , Ni 3 S 2 -Ni 3 Se 2 and CoS 2 -Ni 3 Se 2 interfaces are the active sites for HER.