Toward tuning the surface functionalization of small ceria nanoparticles

• Published in: The Journal of chemical physics 2014-02, Vol.140 (7), p.074703-074703
• Main Authors: Huang, Xing, Wang, Binghui, Grulke, Eric A, Beck, Matthew J
• Format: Article
• Language: English
• Subjects: CERIUM OXIDES; DENSITY; Functional groups; HYDROTHERMAL SYNTHESIS; HYDROXIDES; Hydroxyl groups; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; Mathematical analysis; Nanoparticles; NANOSCIENCE AND NANOTECHNOLOGY; NANOSTRUCTURES; Organic chemistry; PARTIAL PRESSURE; Physics; Quantum mechanics; SURFACES; THERMAL GRAVIMETRIC ANALYSIS; Thermogravimetric analysis
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.4864378

Understanding and controlling the performance of ceria nanoparticle (CNP) catalysts requires knowledge of the detailed structure and property of CNP surfaces and any attached functional groups. Here we report thermogravimetric analysis results showing that hydrothermally synthesized ∼30 nm CNPs are decorated with 12.9 hydroxyl groups per nm(2) of CNP surface. Quantum mechanical calculations of the density and distribution of bound surface groups imply a scaling relationship for surface group density that balances formal charges in the functionalized CNP system. Computational results for CNPs with only hydroxyl surface groups yield a predicted density of bound hydroxyl groups for ∼30 nm CNPs that is ∼33% higher than measured densities. Quantitative agreement between predicted and measured hydroxyl surface densities is achieved when calculations consider CNPs with both -OH and -Ox surface groups. For this more general treatment of CNP surface functionalizations, quantum mechanical calculations predict a range of stable surface group configurations that depend on the chemical potentials of O and H, and demonstrate the potential to tune CNP surface functionalizations by varying temperature and/or partial pressures of O2 and H2O.