Synergistic Oxygen Evolution Catalysis in Intergrown LaNiO ₃ –NiCo ₂ O ₄ Perovskite–Spinel Nanocomposite

This work focuses on a mixed metal oxide electrocatalyst based on a perovskite–spinel intergrown nanocomposite: LaNiO3–NiCo2O4. This nanocomposite was designed and synthesized using a one-pot sol–gel method. By varying the relative fraction of the perovskite and spinel, a series of xLaNiO3–(1–x)NiCo2O4 (where x = 0.1, 0.3, and 0.5) intergrown nanocomposites were obtained and systematically investigated. Structural and morphological characterization confirms the existence of both crystalline phases in an intimately intergrown biphasic nanocomposite where particles are polycrystalline and coalesced together. Electrochemical measurements carried out in an alkaline medium show that the equimolar composite (0.5LaNiO3–0.5NiCo2O4) exhibits enhanced activity, improved reaction kinetics, and better stability compared to the individual components. The improvement in performance is not solely governed by surface area but is primarily associated with intrinsically more active catalytic sites. Pre- and post-OER XPS analyses reveal oxidation-state reconstruction of Ni and Co with the formation of oxyhydroxide intermediates, while gas chromatography confirms enhanced oxygen evolution for 0.5LaNiO3–0.5NiCo2O4.