Oxygen Vacancy‐Enhanced Ternary Nickel‐Tungsten‐Cerium Metal Alloy‐Oxides for Efficient Alkaline Electrochemical Full Cell Water Splitting Using Anion Exchange Membrane

Abstract

Abstract Alkaline water electrolysis is an attractive hydrogen generation technology with ultra‐high purity products and zero carbon emissions. However, the sluggish kinetics of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in both electrodes highly limits their applications. Benefiting from the abundant accessible active sites of the ternary alloy‐oxide structure formed on Ni foam directly, NiCeWO x shows superior HER and OER catalytic performances. The NiCeWO x ‐2 (Ce/W ratio with 5/95) displays enhanced OER activity with an overpotential of 263 mV, while the NiCeWO x ‐1 (Ce/W ratio with 79.8/21.2) shows better performance for alkaline HER with an overpotential of 130 mV at the current density of 10 mA cm −2 . The catalysts show significant enhancement in terms of electrochemical reaction kinetics and conductivity compared to its original NiCeO x and NiWO x alloy phase. The efficient HER‐OER electrocatalytic performance is attributed to its unique alloyed oxygen vacancy structure‐property, which facilitates the diffusion of protons/OH − ions and significantly improves the electron conductivity for catalytic reactions. A low cell potential of 1.65 V is obtained at 10 mA cm −2 for NiCeWO x ‐1||NiCeWO x ‐2 in a full water‐splitting device in 1 M KOH electrolyzer with an anion exchange membrane. Also, NiCeWO x ‐1||NiCeWO x ‐2 exhibits extreme high stability after 24 h operation. This novel design utilizes low‐cost and robust electrocatalysts and will be useful for large‐scale alkaline water electrolysis.