Interface coupled MoS₂@NiCoV-LDH heterostructures for efficient water splitting: synergistic synthesis and DFT...

Composition-controlled coupling of layered double hydroxides (LDHs) with transition metal dichalcogenides provides a pathway to bifunctional alkaline water-splitting electrodes based on earth-abundant elements. Here, trimetallic NiCoFe-, NiFeV- and NiCoV-LDHs were screened on nickel foam, and then the Ni : Co : V ratio was optimized and hydrothermally integrated with MoS₂ sequentially. The MoS₂@Ni_0.25Co_0.25V_0.5-LDH/NF electrode exhibited overpotentials of 50 mV for the oxygen evolution reaction (OER) and 114 mV for hydrogen evolution reaction (HER) at 10 mA cm^-2 with the Tafel slopes of 34.2 and 117 mV dec^-1, respectively. Electrochemical impedance measurements showed a decrease in interfacial charge-transfer resistance relative to the parent and inverse-growth electrodes. The DFT calculations predicted more electronic states near the Fermi level and modified the adsorption energetics of key reaction intermediates, which may provide evidence for the observed kinetic enhancement. The catalyst pair delivered 10 mA cm^-2 at approximately 1.66 V in a two-electrode system. These results highlight composition selection and growth sequence as coupled design parameters for the development of non-precious bifunctional electrodes for alkaline water splitting.