Synthesis of monocarboxylic acid-modified CeO2 nanoparticles using supercritical water

Abstract

This study reports a simple, rapid synthesis technique for the preparation of monocarboxylic acid-modified CeO₂ nanoparticles. 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. The precursor and surface modifiers were heat-treated in a batch-type reactor at 400 °C for 30 min. The carboxylic acids attached to the surface of the products by coordination bonds between the carboxylate (–COO⁻) and Ce ions. The amount of attached surface modifiers tended to increase with increasing alkyl chain length. The products exhibited a cubic morphology and particle sizes of approximately 10 nm, controlled by the surface modifiers. 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.