Hierarchical emulsion based hybrid ceramics synthesized with different siloxane precursor and with embedded nickel nanoparticles

Abstract

An emulsion-based synthesis route for the generation of organo-silica-based monolithic hybrid ceramics with a high content of different organic groups and embedded nickel nanoparticles is presented. By this route hybrid ceramics with a hierarchical pore size distribution and tailorable surface characteristics can be obtained. Mixtures of methyl polysiloxane (MK), tetraethyl orthosilicate (TEOS) and (3-aminopropyl)triethoxysilane (APTES) with varying ratios are selected as precursors, cross-linked, and subsequently pyrolyzed at 500 or 600 °C. In this way monolithic emulsion based hybrid ceramics with three different organo-functionalized siloxane precursor can be synthesized. Additionally, by adding the metal precursor NiCl2, metal-containing emulsion-based hybrid ceramics can be achieved. By adjusting the oil/water ratio and using high- or low internal phase emulsions (HIPEs or LIPEs), controlled micro-, meso-, and macropore distributions are obtained. After pyrolysis, materials achieve specific BET surface areas of up to 550 m2/g. Adjustable surface characteristics in terms of hydrophobicity and hydrophilicity of the material surface by thermal decomposition behavior of precursors is demonstrated. Nickel is incorporated through the formation of complexes with APTES, resulting in well-distributed metal nanoparticles with average particle sizes between 35 and 69 nm. The material properties are pivotal features for catalysis and gas separation applications.