Rational design of novel NiBi-LDH with enhanced overall water splitting activity

Layered double hydroxides (LDHs) are among the most important materials considered in the redox reaction of water electrolysis. In this study, a new LDH containing Ni and Bi in the cationic layers was synthesized through a solvothermal method. The physicochemical characteristics of the synthesized LDH were investigated using various techniques such as XRD, FE-SEM, EDX, BET, FT-IR, and Raman. The efficiency of the NiBi-LDH catalyst supported on nickel foam (NB/NF) was evaluated for the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER). To improve the overall water-splitting performance of the synthesized LDH, it was modified with NiMoO4 (NMO). The electrochemical activity, kinetics, mechanism, and stability of the modified samples were studied using various techniques such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronopotentiometry. The electrochemical results showed that the NB/NF catalyst had overpotentials of 202 and 264 mV for HER and OER, respectively. However, the addition of NMO to the NB/NF catalyst resulted in a significant improvement in the overall performance, with a small overpotential of only 84 and 160 mV (at 10 mA cm−2) for HER and OER, respectively, and a very small Tafel slope of 45.7 and 74.9 mV.dec−1. The potential for overall water-splitting was found to be 1.424 V. The NB-NMO/NF catalyst demonstrated excellent kinetics, stability, and durability.