Anchoring Gold Nanoparticles on Functionalized Halloysite Nanotubes: Density Functional Theory and Experimental Studies

The structural and catalytic properties of gold nanoparticles are known to be highly sensitive to cluster size, dimensionality, and interactions with the support. In this work, a combined theoretical and experimental approach was employed to investigate systems in which gold nanoclusters are anchored on functionalized halloysite nanotubes. Density functional theory calculations were performed to explore the geometric and electronic characteristics of the anchored Au _<i>n</i> (<i>n</i> = 1 - 20) clusters and their interactions with the amino-functionalized support. Multiple anchoring configurations were assessed, with optimized geometries and Au-N interaction distances analyzed in detail. Results indicate a transition from a two-dimensional to a three-dimensional cluster structure occurring at a lower number of atoms if compared with the case of isolated Au _<i>n</i> clusters, mainly due to the overall interaction with the halloysite silanolic groups. Complementarily, gold nanoparticles were synthesized and deposited onto functionalized HNTs, and the resulting materials were characterized using experimental techniques. The study demonstrates that halloysite-based hybrid materials offer a promising platform for stabilizing small gold clusters, with potential application as heterogeneous catalysts.