Nonequilibrium Process for Doping Under Continuous-Flow Hydrothermal Synthesis of Cerium Oxide-Based Nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Nonequilibrium composition is crucial for nanoparticle production.
• Understanding nanoparticle formation dynamics under nonequilibrium conditions is essential for developing advanced materials.

Purpose of the Study:

• To synthesize chromium-doped cerium dioxide (Cr-CeO₂) nanoparticles using continuous-flow hydrothermal synthesis.
• To investigate the effect of temperature and reaction time on the nonequilibrium composition of synthesized nanoparticles.
• To explore the potential of this method for fabricating nanomaterials with unique compositions.

Main Methods:

• Continuous-flow hydrothermal synthesis at temperatures of 300, 350, and 400 °C.
• Precise control of reaction times on the order of seconds.
• Analysis of nanoparticle composition and structural evolution over time.

Main Results:

• Cr-rich CeO₂ nanoparticles formed initially due to low surface energy.
• Cr content decreased over time as particles approached equilibrium.
• Unusual nonequilibrium compositions were achieved through rapid heating and short residence times.
• Similar results were observed for other dopants like iron (Fe) and europium (Eu).

Conclusions:

• Continuous-flow hydrothermal synthesis is an efficient method for producing nanomaterials with unique, nonequilibrium compositions.
• This technique enables the fabrication of materials with compositions unattainable by conventional batch methods.
• The rapid heating and short residence times are key to achieving these unusual compositions.