Toward layered double oxide-based nanomaterials: From synthesis to diverse applications

Layered double oxides (LDOs), derived from the calcination of layered double hydroxides (LDHs), have emerged as a prominent class of 2D multifunctional materials. Their structural transformation generates a defect-rich, high-surface-area framework with tunable basicity, mixed-valence cations, and the unique “memory effect” that allows reversible reconstruction into LDHs. These characteristics lead to considerable catalytic, adsorptive, and electrochemical performance for LDOs. This review critically examines synthesis strategies, from calcination and templating to emerging low-temperature and exfoliation routes, and correlates structural evolution with different functionalities. Analysis of reports highlights the versatility of LDOs in pollutant remediation, energy conversion and storage, and biomedical systems, where their defect-engineered surfaces exhibit high reactivity and selective interactions. Despite recent progress, challenges remain in both synthesis and application. Nonetheless, due to their unique physicochemical properties, the translation of LDOs from laboratory materials to practical technologies is expected in the future.