Phase Segregation in Cu0.5Ni0.5 Alloy Boosting Urea‐Assisted Hydrogen Production in Alkaline Media

Abstract Coupling urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) is promising for energy‐efficient hydrogen production. However, developing cheap and highly active bifunctional electrocatalysts for overall urea electrolysis remains challenging. In this work, a metastable Cu 0.5 Ni 0.5 alloy is synthesized by a one‐step electrodeposition method. It only requires the potentials of 1.33 and −28 mV to obtain the current density of ±10 mA cm −2 for UOR and HER, respectively. The metastable alloy is considered to be the main reason causing the above excellent performances. In the alkaline medium, the as‐prepared Cu 0.5 Ni 0.5 alloy exhibits good stability for HER; and conversely, NiOOH species can be rapidly formed during the UOR due to the phase segregation of Cu 0.5 Ni 0.5 alloy. In particular, for the energy‐saving hydrogen generation system coupled with HER and UOR, only 1.38 V of voltage is needed at 10 mA cm −2 ; and at 100 mA cm −2 , the voltage decreases by ≈305 mV compared with that of the routine water electrolysis system (HER || OER). Compared with some catalysts reported recently, the Cu 0.5 Ni 0.5 catalyst owns superior electrocatalytic activity and durability. Furthermore, this work provides a simple, mild, and rapid method for designing highly active bifunctional electrocatalysts toward urea‐supporting overall water splitting.