Cerium oxide films

Fig. 12.2. The surface atom concentration ratio [Ce] to ([Ce] + [M]), in which M is either Al, Zn, or Fe, as a function of thickness of cerium oxide film, both determined by AES profiling, for alloys immersed in solution for the number of days indicated (from R.B.W. Hinton in Reviews on Corrosion Inhibitor Science and Technology (1993), edited by A. Raman and P. Labine, 1-10-1. Copyright by NACE International. All rights reserved by...

The formation of a rare earth metal oxide on the metal surface, impedes the cathodic reduction of oxygen and thus cathodic inhibition is achieved by the addition of a rare earth metal salt to a system. The surface atom concentration ratio, [Ce/Ce + M], where M is Fe, Al or Zn, is a function of cerium oxide film thickness determined by AES depth profiles as shown in Fig. 12.2. 

Hardacre el al. (7 75, 174) investigated the properties, structure, and composition of cerium oxide films prepared by cerium deposition on Pt(lll), finding that the activity for CO oxidation is enhanced on Pt(lll) that is partially covered by ceria. It was suggested that new sites at the Pt-oxide interface become available for reaction. A remarkable observation is the high activity for CO oxidation when the Pt(lll) sample is fully encapsulated by ceria (Pt was undetectable by XPS and AES). It was proposed that an ultrathin, disordered ceria film becomes the active catalyst. It was also demonstrated by XPS and AES that Pt dramatically increases the reducibility of cerium oxide that is in intimate contact with Pt. This result suggests that intimate contact between the noble metal and oxide phases is indeed crucial to facile oxygen release from ceria. High-resolution electron microscopy demonstrated the presence of direct contact between ceria and noble metal for supported Pt-Rh catalysts (775). Hardacre et al. (173,174) related the catalytic activity of the ceria phase to partially reduced cerium oxide. 

Figure 3 shows a typical experimentally obtained corrosion diagram E-lg i, illustrating the kinetics of the cathodic and anodic processes on the studied steel in the absence of electrochemically deposited cerium oxides film (the curves 2) and after the deposition of thin oxide films with different surface concentrations of Ce (curves 3-5). 

Li, F.B., Newman, R.C., and Thompson, G.E., In situ atomic force microscopy studies of electrodeposition mechanism of cerium oxide films Nucleation and growth out of a gel mass precursor. Electrochimica Acta, 1997. 42(16) 2455-2464. 

Ershov S., Druart, M.-E., Poehnan, M., Cossement, D., Snyders, R. and Olivier, M-G. 2013. Deposition of cerium oxide films by reactive magnetron sputtering for the development of corrosion protective coatings. Corrosion Science, 75,158-168. 

Figure 2. Optical Micrograph of an electrodeposited cerium oxide film on stainless steel. 800x magnification, (from T.

Figure 4. X-ray diffraction patterns of cerium oxide films deposited at a pH of (A) 7.5, (B) 8.5 and (C) 10.5. Deposition temperature, 70 °C janodk " -0.06 mA/cm. Y-axis represents x-ray intensity in cps.

Wang AQ, Golden TD. Electrodeposition of oriented cerium oxide films. Int. J. Elec-trochem. 2013 482187 1-10. DOT 10.1155/2013/482187. 

Li F, Thompson GE, Newman RC. Force modulation atomic force microscopy background, development and application to electrodeposited cerium oxide films. Appl. Surf. Sci. 1998 126 21-33. DOI 10.1016/50169-4332(97)00590-4. 

Li F, Thompson GE. In situ atomic force microscopy studies of the deposition of cerium oxide films on regularly corrugated surfaces. J. Electrochem. Soc. 1999 146 1809-1815. DOI 10.1149/1.1391848. 

Yang L, Pang X, Fox-Rabinovich G, Veldhuis S, Zhitomirsky I. Electrodeposition of cerium oxide films and composites. Surf. Coat. Technol. 2011 206 1-7. DOI 10.1016/ j.surfcoat.2011.06.029. 

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