Synergistic interfacial dynamics of CoFe-LDH@ZnCo2O4 as robust hybrid heterostructures for sustainable water electrolysis

Abstract

The development of efficient and stable cobalt-based spinel oxide catalysts is crucial for sustainable and clean energy production through electrocatalytic water splitting. Layered double hydroxides (LDHs) have emerged as a promising class of non-noble metal electrocatalysts for both hydrogen and oxygen evolution reactions. In this study, we report the hybrid heterostructure CoFe-LDH@ZnCo₂O₄ on a self-supported nickel foam substrate (ZCF-LDH/NF) using a cost-effective two-step hydrothermal process. The robust interfacial network and abundant catalytically active sites of ZCF-LDH/NF facilitate efficient charge transfer. The resulting ZCF-LDH/NF catalyst exhibits remarkable bifunctional electrocatalytic activity, achieving low overpotentials of approximately 290 mV and 296 mV for the oxygen evolution reaction (OER) and 195 mV and 208 mV for the hydrogen evolution reaction (HER) at a current density of 50 mA cm⁻² in both fresh and simulated alkaline seawater, respectively. Additionally, the integrated water electrolyzer featuring ZCF-LDH/NF₍₋₎‖ZCF-LDH/NF₍₊₎ electrodes demonstrates impressive performance, requiring only 1.61 V to reach 10 mA cm⁻² in alkaline and 1.64 V in simulated alkaline conditions. Further, Mott–Schottky analysis reveals the semiconductor properties and flat-band potentials of the components, providing insights into the charge transfer mechanisms. First-principles density functional theory calculations unveil the creation of more active sites on the CoFe-LDH surface, contributing to the heterostructure's overall catalytic activity. Notably, this work presents spinel oxide/LDH-based heterostructures as efficient and cost-effective catalysts with negligible catalytic activity loss, offering great potential for sustainable hydrogen production and energy conversion applications.