Nickel hydroxide array coated with NiFe alloy nanosheets for overall mixed water splitting

In this study, Ni(OH)2 coated NiFe alloy with Mott-Schottky structure is successfully prepared by hydrothermal and in-situ electrodeposition methods. The materials are characterized by physical and electrochemical characterizations, and the results show that Ni(OH)2 @NiFe/NF has better catalytic activities than other monomers. Furthermore, the Ni/Fe ratio in the electrodeposition step and the CV deposition cycles could affect the performances. While the sample with Ni/Fe= 2:2 and 60 CV deposition cycles (Ni(OH)2 @Ni2Fe2/NF-60) exhibits the best activities towards hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and urea oxidation reaction (UOR). Furthermore, the two-electrode electrolyzer composed of Ni(OH)2 @Ni2Fe2/NF-60 exhibits the smallest driving potential (1.696 V (HER&OER) and 1.601 V (HER&UOR) at 50 mA·cm−2), with excellent stability. These may be due to the Mott-Schottky structure (metal-semiconductor interface) could reduce the binding energy of hydrogen atoms, promote charge transfer and generate abundant active sites, while producing a synergistic effect and promoting electrocatalytic reactions.