Alkaline Water Electrolysis by NiZn-Double Hydroxide-Derived Porous Nickel Selenide-Nitrogen-Doped Graphene Composite

The large-scale application of water electrolysis for the generation of hydrogen can be made viable only by the development of inexpensive, robust, and bifunctional electrocatalysts. Here, we report a self-templating method for the design of porous, edge-site-rich hybrid nanomaterials via the selective etching of layered double hydroxide precursors that contain an amphoteric metal by alkali treatment, followed by vapor phase selenization. The obtained hexagonal nickel selenide nanoplates anchored over nitrogen-doped graphene showed highly efficient and robust oxygen evolution reaction (OER) electrocatalysis due to the inherent in situ electrochemical oxidation property of selenides demonstrating low overpotential of 311 mV to achieve the 10 mA cm' water oxidation current density in 1 M KOH. The faster reaction kinetics and long-term stability of the catalyst encouraged us to demonstrate a real alkaline water electrolyzer, which enables high-performing overall water splitting with a low overpotential of 460 mV from theoretical potential of 1.23 V to generate sufficient amounts of H-2 and O-2 by achieving a current density of 10 mA cm(-2). This study thus provides a valuable strategy to tailor the surface texture of the catalyst as well as its effectiveness in developing robust multifunctional electrocatalysts, promoting the efficient design of porous materials for catalytic applications.