Open Access Open Access  Restricted Access Subscription Access

Elucidating the chemical state of elements in CaO-CuO-CeO2 mixed oxide by X-ray photoelectron spectroscopy

Pham Anh Son, Hoang Thi Huong Hue


In this research, three-component-oxide CaO-CuO-CeO2 was fabricated a sol-gel method. This mixed oxide acted as the catalysts for the complete oxidation of phenol in the presence of hydro peroxide. The activity of the catalyst was monitored versus fabrication conditions of mixed oxide such as aging temperature, calcination temperature and time. Under the optimum conditions including aging temperature at 70 oC, calcination at 600 oC for 30 min, the catalyst gave the best activity with 96.3% phenol conversion. Among tested mixed oxides or single oxides, three-component-oxide CaO-CuO-CeO2 exhibited the highest performance. The chemical state of metal elements in the mixed oxide was carefully studied by high-resolution X-ray photoelectron spectroscopy (XPS) technique. The XPS spectra of Ca 2p, Cu 2p, and Ce 3d were recorded in ranges of 935-965, 927-967, and 878-930 eV, respectively. The curve fitting processes were carried out on CasaXPS version 2.3.18PR1.0 software with Shirley or Tougaard background and GL(m) line shape. Some constraints such as the FWHM, splitting energy and peak area ratio of spin-orbit interaction were introduced into the fitting process in order to achieve the highest physical meaning of the spectrum deconvolution. The fitting result proved the coexistence of Ce4+, Ce3+, Cu2+ and Cu+ in the component of the prepared material. The formation of Ce3+ and Cu+ from the interaction between Ce4+ and Cu2+ accompanied the appearance of oxygen vacancies in the crystal structure of CeO2 support. That process was enhanced by the presence of calcium element. Oxygen vacancies played important role in the formation of superoxide anions that were the highly active intermediate for the phenol oxidation.

Keywords. X-ray photoelectron spectroscopy, binding energy, chemical state, CaO-CuO-CeO2, phenol oxidation.


X-ray photoelectron spectroscopy, binding energy, chemical state, CaO-CuO-CeO2, phenol oxidation


D. Delimaris and T. Ioannides. VOC Oxidation over CuO-CeO2 Catalysts Prepared by a Combustion Method, Appl. Catal. B, 89, 295-302 (2009).

D. Qiao, G. Lu, D. Mao, X. Liu, H. Li, Y. Guo and Y. Guo. Effect of Ca Doping on the Catalytic Performance of CuO-CeO2 Catalysts for Methane Combustion, Catal. Commun., 11, 858-861 (2010).

L. S. Clesceri, A. Geenberg, Standard Method for the Examination of Water and Wastewater, 20th Ed., American Public Health Association, Washington DC (1998).

Y. Liu, Q. Fu, M. F. Stephanopoulos. Preferential Oxidation of CO in H2 over CuO-CeO2 Catalysts, Catal. Today, 93-95, 241-246 (2004).

J. Astudillo, G. Águila, F. Díaz, S. Guerrero and P. Araya, Study of CuO-CeO2 Catalysts Supported on SiO2 on the Low-temperature Oxidation of CO, Appl. Catal. A, 381, 169-176 (2010).

N. F. P. Ribeiro, M. M. V. M. Souza and M. Schmal. Combustion Synthesis of Copper Catalysts for Selective CO Oxidation, J. Power Sources, 179, 329-334 (2008).

P. Massa, F. Ivorra, P. Haure and R. Fenoglio. Catalytic Set Peroxide Oxidation of Phenol Solutions over CuO/CeO2 Systems, J. Hazard Mater., 190, 1068-1073 (2011).

X. C. Zheng, S. P. Wang, S. R. Wang, S. M. Zhang, W. P. Huang and S.H. Wu. Preparation, Characterization and Catalytic Properties of CuO/CeO2 System, Mater. Sci. Eng. C, 25, 516-520 (2005).

C. Hu. Enhanced Catalytic Activity and Stability of Cu0.13Ce0.87Oy Catalyst for Acetone Combustion: Effect of Calcination Temperature, Chem. Eng. J., 159, 129-137 (2010).

M. Fu, X. Yue, D. Ye, J. Ouyang, B. Huang, J. Wu and H. Liang. Soot Oxidation via CuO Doped CeO2 Catalysts Prepared Using Coprecipitation and Citrate Acid Complex-ombustion Synthesis, Catal. Today, 153, 125-132 (2010).

J. A. Rodriguez, X. Wang, J. C. Hanson, G. Liu, A. Iglesias-Juez and M. Fernández-Garcı́a. The Behavior of Mixed-metal Oxides: Structural and Electronic Properties of Ce1−xCaxO2Ce1−x CaxO2 and Ce1−xCaxO2−x, J. Chem. Phys., 119, 5659-5669 (2003).

NIST X-Ray Photoelectron Spectroscopy Database: Accessed date: April 4th, 2017.

C. M. Chanquía, K. Sapag, E. Rodríguez-Castellón, E. R. Herrero, G.A. Eimer. Nature and Location of Copper Nanospecies in Mesoporous Molecular Sieves, J. Phys. Chem. C, 114, 1481-1490 (2010).

Y. Zhou, J. M. Perket and J. Zhou. Growth of Pt Nanoparticles on Reducible CeO2(111) Thin Films: Effect of Nanostructures and Redox Properties of Ceria, J. Phys. Chem. C, 114, 11853-11860 (2010).

A.S. Dieza, M. Graziano-Mayera, G. Radivoya, M. A. Volpeb. Suzuki–Miyaura Cross-coupling of Aryl Iodides and Phenylboronic Acid over Palladium-free CeO2 Catalysts, Appl. Catal. A, 482, 24-30 (2014).

Z. Liu, R. Zhou and X. Zheng. Comparative Study of Different Methods of Preparing CuO-CeO2 Catalysts for Preferential Oxidation of CO in Excess Hydrogen, J. Mol. Catal., A: Chem., 267, 137-142 (2007).

M .F. Luo, Y. P. Song, J. Q. Lu, X. Y. Wang and Z.

Y. Pu. Identification of CuO Species in High Surface Area CuO-CeO2 Catalysts and Their Catalytic Activities for CO Oxidation, J. Phys. Chem., C, 111, 12686-12692 (2007).

R. Zhang, T. Haddadin, D. P. Rubiano, H. Nair, C. S. Polster and C.D. Baertsch. Quantification of Reactive CO and H2 on CuOx-CeO2 During CO Preferential Oxidation by Reactive Titration and Steady State Isotopic Transient Kinetic Analysis, ACS Catal., 1, 519-525 (2011).

Q. Liang, X. Wu, D. Weng and Z. Lu. Selective Oxidation of Soot over Cu Doped Ceria/Ceria–Zirconia Catalysts, Catal. Commun., 9, 202-206 (2008).

Full Text: PDF


  • There are currently no refbacks.