Layered rare-earth stabilized Bi2O3: Organic amines intercalation under ambient conditions and their role as a solid adsorbent for iodine

Abstract

Intercalation chemistry is pivotal in discovering the dimension-dependent properties of 2D materials and expanding their applications. Layered bismuth oxide with composition Bi0.775Ln0.225O1.5 (Ln = La, Pr, Nd, Sm, and Eu) has been demonstrated to intercalate both aliphatic and aromatic amines, resulting in the unit cell expansion along the c-axis. Aliphatic amines were present in a vertical orientation, whereas aromatic amines preferred a horizontal orientation. The intercalated amine concentrations ranged from 0.15 to 0.54 mole per mole of the host. Among the chosen amines, ethylenediamine intercalation enhanced the c-axis of Bi0.775Pr0.225O1.5 by 20 Å, justified by the high amounts of intercalant and intermolecular hydrogen bonding between them, resulting in a bilayer arrangement. The lamellar-plate-like morphology filled with intercalants and twinning collapse was noticed in the FESEM and SAED patterns after the intercalation process. The ethylenediamine intercalated Bi0.775Pr0.225O1.5 was further evaluated for iodine adsorption from non-aqueous solutions through chemisorption following pseudo-second-order kinetics. The X-ray diffraction peaks after adsorption suggested bilayer to monolayer transformation aided by chemical alterations within the host's van der Waals gaps. The N–I vibration mode, observed in the FTIR spectrum of the iodine-adsorbed sample, further augmented the interaction between the two during adsorption.