Study of Growing Ni Nanoparticles Loaded on Layered Inorganic-Imidazoline Covalently Bonded Hybrids Under a Transmission Electron Microscope

Abstract

This study investigates nanoclusters loaded on layered inorganic-imidazoline covalently bonded hybrids. To reveal the existence of nanoclusters, transmission electron microscopy (TEM) and selected-area diffraction (SAD) analyses were performed. An imidazolyl group bonded covalently with an inorganic layer, which contained Ni²⁺ (and not Mg²⁺) as an octahedral cation, in the layered hybrids. In this study, the layered hybrids synthesized at 170 and 150 °C are referred to as Ni-Im₁₇₀ and Ni-Im₁₅₀, respectively. The TEM observations confirmed the presence of nanoclusters of 1–2 nm in diameter on thin sheets of Ni-Im₁₇₀ and Ni-Im₁₅₀. The nanoclusters appeared as dark dots in the bright-field images and were brighter than the thin sheets in dark-field images. The SAD analyses exhibited halo patterns similar to those of phyllosilicates at the beginning of the TEM observations. The TEM analyses further revealed that the nanoclusters in both Ni-Im₁₇₀ and Ni-Im₁₅₀ grew into Ni nanoparticles (3–5 nm diameter) under TEM. The SAD analyses demonstrated diffraction patterns with a weak ring with a d-value of 0.20 nm and/or diffraction patterns attributed to Ni exhibiting rings with d-values of 0.20, 0.18, 0.12, and 0.11 nm after the nanocluster growth. Furthermore, in the case of Ni-Im₁₅₀, drastic growth was observed under TEM, i.e., the diameters increased to approximately 30 nm.