Tailoring crystallinity, porosity, and thermal stability in silica-copper composite aerogels and xerogels through controlled co-gelation

Abstract

A comprehensive investigation was performed to evaluate the influence of synthetic and processing parameters on the structural characteristics, thermal stability, and surface chemistry of silica-copper composite aerogels and xerogels. Annealing in air resulted in the corresponding heat-treated counterparts. A series of novel silica-copper composite aerogels and xerogels was successfully prepared through the co-gelation of tetramethoxysilane with either copper chloride or copper nitrate precursors, using an epoxide as gelation-initiating agent. The influence of progressive increases in chloride content within the sol was further investigated. Batch yields reached a maximum of 3.5 g, a limitation solely imposed by the capacity of the critical point dryer, whereas the synthesis protocol demonstrates considerable potential for scalability. In both material forms, the Si/Cu molar ratios were found to closely match those of the initial precursor solutions, confirming negligible compositional loss throughout the synthesis process. Comprehensive characterization was performed using X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption, scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis were combined and analyzed. The results confirm the successful co-gelation of copper and silica under well-defined conditions, yielding materials characterized by high thermal stability, predominantly amorphous structures, and compositional homogeneity at the atomic scale. The controlled incorporation of polydisperse copper crystalline entities within the porous network was also successfully realized. The resulting materials exhibited high surface areas, well-developed open pore architectures, and enhanced thermal stability, properties attributable to strong interactions between the copper species and the silica matrix.

The authors' abstract, as published at the source. Journal of Non-Crystalline Solids, 2026 · DOI ↗