Oxidizing synthesis of Ni–Mn layered double hydroxide with good crystallinity

Ni²⁺–Mn³⁺ layered double hydroxide (LDHs) with good crystallinity and uniform morphology has been hydrothermally synthesized at 180 °C for 2 days using urea as hydrolysis agent and ammonium peroxodisulfate as oxidant. The obtained Ni²⁺–Mn³⁺ LDHs material has been characterized by XRD, SEM, XPS, FT-IR, and TG–DTA. Ammonium peroxodisulfate as oxidant plays an important role for the formation of Ni²⁺–Mn³⁺ CO₃²⁻ LDHs material, and Mn²⁺ ions are oxidized into Mn³⁺ ones during the precipitation of Mn²⁺ ions, giving rise to layered hydroxide with the hydrotalcite structure. Ni²⁺–Mn³⁺ LDHs material with Ni/Mn molar ratio of 4 has a layered structure with a basal spacing of 0.739 nm. The morphology, size, and uniformity of the as-prepared materials connect with the hydrothermal treatment temperatures, and uniform and regular flowerlike spheres with a mean lateral size of 3.5 μm are observed for Ni²⁺–Mn³⁺ LDHs material with good crystallinity and uniform morphology.