Non-Noble Metal–Organic Framework (CuV-MOF) on Graphene-Coated Nickel Foam Enables High-Performance Overall Natural Seawater Splitting

To facilitate clean energy fuel production via water electrolysis, a durable and highly efficient electrocatalyst is crucial. In this study, a copper–vanadium bimetallic metal–organic framework (MOF) was synthesized on graphene-coated nickel foam (GNF). A comprehensive analysis of possible combinations revealed the optimal Cu:V ratio, yielding low overpotentials (η10) of 220 mV for the oxygen evolution reaction (OER) and 104 mV for the hydrogen evolution reaction (HER). Compared with pristine nickel foam, impedance analysis demonstrated that the interfacial graphene layer significantly enhanced charge transport. While the graphene-coated electrodes displayed stable overall water-splitting performance in both alkaline and seawater conditions, the CuV-MOF/NF combination degraded within 20 h. Further electrochemical analysis and X-ray photoelectron spectroscopy confirmed that the graphene coating protected the nickel foam from a harsh electrolyte environment and prevented oxidation.