Comparable study of vermiculites from four commercial deposits prepared with fixed ceria nanoparticles

Abstract Four commercial macroscopic vermiculites (Ver) from different exploited deposits were investigated regarding their chemistry and structural transformation stage from mica (phlogopite), and compared with selected raw vermiculites and “hydrobioties” known from literature, in which the chemical analyzes verified the existence of iron as Fe 3 + and Fe 2 + . Subsequently prepared vermiculite/ceria (Ver/CeO 2 ) nanoparticles composites were compared from the point of view of the fixation of ceria nanoparticles by using stability test and regarding their photocatalytic activity in the decomposition of N 2 O. The experimental methods used for these studies were X-ray fluorescence spectrometry, atomic emission spectrometry, X-ray powder diffraction, infrared (FR-IR) and Raman spectroscopy and transmission electron microscopy with high resolution (HRTEM). Negative layer charge of vermiculites produced by the local charge balance and distribution of Fe 3 + in tetrahedral and octahedral sheets were related to the CeO 2 nanocrystals fixation and orientation. Among the four Ver/CeO 2 nanoparticles composite samples, the vermiculite in sample Ver-C/CeO 2 exhibited the highest negative layer charge. The CeO 2 crystallites were the smallest among all four samples. HRTEM found separated CeO 2 nanocrystallites and CeO 2 agglomerates of differently oriented nanocrystallites. Such forms of CeO 2 nanocrystals influenced the position of the Raman CeO 2 F 2g and suppressed ability for photocatalytic N 2 O conversion.