Near- and Supercritical Alcohols as Solvents and Surface Modifiers for the Continuous Synthesis of Cerium Oxide Nanoparticles

Abstract

Supercritical fluids offer fast and facile routes toward well-crystallized tailor-made cerium oxide nanoparticles. However, the use of surfactants to control morphology and surface properties remains essential. Therefore, although water, near-critical (nc) or supercritical (sc), is a solvent of choice, the poor water solubility of some surfactants could require other solvent systems such as alcohols, which could themselves behave as surface modifiers. In here, the influence of seven different alcohols, MeOH, EtOH, PrOH, iPrOH, ButOH, PentOH, and HexOH, in alcothermal conditions (300 °C, 24.5 MPa) over CeO(2) nanocrystals (NCs) size, morphology, and surface properties was investigated. The crystallite size of the CeO(2) nanocrystals can be tuned in the range 3-7 nm depending on the considered alcohol, and their surface has been modified by these solvents without the use of surfactants. Mechanisms are proposed for the interaction of primary and secondary alcohols with CeO(2) surface and its functionalization during the synthesis based on FTIR and TGA-MS studies. This study allows apprehending the role of alcohols during the synthesis and may lead to an informed choice of solvent as a function of the required size and surface properties of CeO(2) NCs. It also opens new route to CeO(2) functionalization using supercritical alcohol derivatives.

Influence of the Incorporation of CeO2 Nanoparticles on the Ion Exchange Behavior of Dodecylsulfate Doped Polypyrrole Films: Ac-Electrogravimetry Investigations

“…Numerous CeO 2 synthesis procedures have been reported in literature [10][11][12][13] leading to various nanoparticle morphologies. These materials were extensively studied owing to their many distinctive characteristics and applications such as catalysts in the fuel cell technology [14], gas sensor [15], catalytic wet oxidation [16][17], oxygen storage and release [18], wastewater treatment [19] or photo-catalytic oxidation of water [20].…”

Ultra-simple synthetic approach to the fabrication of CeO2–ZrO2 mixed nanoparticles into homogeneous, domain, and core–shell structures in mesoporous spherical morphologies using supercritical alcohols

“…However, CeO 2 -ZrO 2 -SH exhibited a mixed profile of cubic Next, a step-wise synthesis was applied to obtain ZrO 2 @CeO 2 core-shell NPs with a ZrO 2 core and a CeO 2 shell (Fig.1). We then changed the solvent as an attempt to generate a thicker outer shell of cubic CeO 2 , since some of secondary alcohols are reported to yield larger size CeO 2 crystalline particles [38].…”

Continuous synthesis of Li4Ti5O12 nanoparticles in supercritical fluids and their electrochemical performance for anode in Li-ion batteries

“…Prior to calcination, crystallite size, estimated using the Scherrer equation, is in the order of LTO-scH 2 O (5.2 nm) > LTO-scMeOH (3.8 nm). The smaller crystallite size of LTO-scMeOH compared to LTO-scH 2 O could be due to the surface modification effect originating from supercritical methanol, thus inhibiting the crystal growth [26,27,35]. After the calcination, an increase in crystallite size is observed; the crystallite sizes of LTO-scH 2 O-Air-600C, LTO-scMeOH-Air-600C, and LTO-scMeOH-H 2 -600C were estimated to be 36.7 nm, 98.2 nm, and 34.2 nm, respectively.…”