13,14 Therefore, the physical properties can be tuned not only by controlling the particle size and morphology but also by surface modification.
In fact, in the case of metal oxides, surface modification enables to control the valence state of metal ions (and the amount of oxygen vacancies, ionic distributions, etc.) in the nanoparticles. 1–15 During the formation of hybrid nanoparticles, interactions at the interface between the organic molecules and the crystallite surface of the inorganic nanoparticles control the particle size and morphology of the resulting inorganic structures, 1–15 thus affecting their physical properties. Introduction Hybrid organic–inorganic nanoparticles have attracted considerable interest for various applications because they combine the merits of organic molecules, such as wide tunability and structural flexibility, with the physical properties of inorganic nanoparticles including magnetic, electronic, catalytic, and optical properties. Surface modification also controlled the band gap of the products, suggesting the possibility of tuning their electronic and optical properties by using organic surface modifiers. The products exhibited a cubic morphology and particle sizes of approximately 10 nm, controlled by the surface modifiers. The amount of attached surface modifiers tended to increase with increasing alkyl chain length.
The carboxylic acids attached to the surface of the products by coordination bonds between the carboxylate (–COO −) and Ce ions. The precursor and surface modifiers were heat-treated in a batch-type reactor at 400 ☌ for 30 min. The nanoparticle products were prepared under hydrothermal conditions using supercritical water and Ce(OH) 4 as a precursor in the presence of monocarboxylic acids with different alkyl chain lengths (C6–18) acting as surface modifiers. This study reports a simple, rapid synthesis technique for the preparation of monocarboxylic acid-modified CeO 2 nanoparticles.