From Binary to High-Entropy Layered Double Hydroxides: Influence of Increasing Cation Complexity on Structure, Morphology, and Textural Properties

High-entropy layered double hydroxides (HE-LDHs) combine the layered structure of conventional layered double hydroxides with multicationic hydroxide layers, making them promising and tailorable materials for applications including wastewater treatment, electrocatalysis, and as precursors to porous high-entropy oxides. In this work, we present a systematic study of increasing cation complexity, and the associated configurational entropy in LDHs by starting from a binary Mg/Al LDH synthesized hydrothermally and incrementally introducing Cr, Fe, Ni, Co, and Zn to ultimately form a seven-cation HE-LDH. This compositional progression enables direct evaluation of how increasing cation complexity influences the structure, morphology, and physicochemical properties of the resulting materials.Scanning electron microscopy shows a progressive transition from well-defined platelet-like particles to smaller, less-defined morphologies as cation complexity increases. Powder X-ray diffraction shows a corresponding decrease in crystallinity while retaining the characteristic LDH structure. Raman spectroscopy further reveals progressive changes and broadening of the metal–oxygen vibrations, consistent with an increasingly complex and locally distorted metal–oxygen environment. These changes are accompanied by an increase in BET surface area from 82 to 133 m² g⁻¹ and enhanced mesoporosity. Rather than exhibiting an abrupt transition at a nominal high-entropy composition, the structural, morphological, and textural properties evolved progressively with increasing cation complexity, suggesting that the high-entropy LDH represents part of a continuous compositional progression from conventional LDHs rather than a distinct structural regime.