Rose-like Cu-doped Ni3S2 nanoflowers decorated with thin NiFe LDH nanosheets for high-efficiency overall water and urea electrolysis

Water electrolysis is a promising way to produce green hydrogen energy but still limited by the sluggish anodic oxidation kinetics. Herein, we firstly introduced a multifunctional electrocatalyst of rose-like Cu-doped Ni3S2 nanoflowers decorated with thin NiFe LDH nanosheets (Cu-Ni3S2@NiFe LDH) with excellent hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and water electrolysis performance. More impressively, Cu-Ni3S2@NiFe LDH-200 target catalyst shows the huge potential to replace the slow OER with urea electrolysis when it is used to catalyze urea oxidation reaction (UOR). In addition, the structure-function relationship of material was highlighted and the performance of target catalyst was well revealed by analyzing the growth law of NiFe LDH on Cu-doped Ni3S2. It's worth noting that Cu-Ni3S2@NiFe LDH-100 performs well for HER, while Cu-Ni3S2@NiFe LDH-200 stands out for OER and UOR. The resulting Cu-Ni3S2@NiFe LDH-200(+)//Cu-Ni3S2@NiFe LDH-100(-) electrode couple only requires 1.502 V and 1.413 V to deliver the same current density of 10 mA cm−2 for water electrolysis and urea electrolysis and catalyzed stably for over 20 h, which is one of the best catalytic activities reported so far. Our work will open a new idea to enhance the catalytic activity and stability of transition metal sulfides with layered double hydroxides.