Absorption and Decomposition of CO 2 by Active Ferrites Prepared by Atmospheric Plasma Spraying
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echnical Note
Absorption and Decomposition of CO2 by Active Ferrites Prepared by Atmospheric Plasma Spraying Shaowei Li, Zhida He, Yanjun Zheng, and Changfeng Chen (Submitted July 4, 2015; in revised form September 17, 2015) Active ferrites, which play an important role in the catalytic decomposition of CO2, have been fabricated by atmospheric plasma spraying to incorporate FeO and anoxic iron oxide [Fe3O42d (0 < d < 1)]. The complexity of phase composition, especially the presence of FeO, gives the resulting powder a greater ability to decompose CO2 when compared to hydrogen-reduced Fe3O4 or Fe2O3 particles. Spraying distance is found to play an important role in modulating the decomposition ability of the powders, while elevated temperatures can also enhance the catalytic decomposition of CO2.
Keywords
active ferrite, anoxic oxide, atmospheric plasma spraying, CO2 decomposition, FeO, in-flight oxidation, iron
1. Introduction Superhydrophobic surfaces have been the subject of much research due to their potential for use in a wide range of fields such as corrosion prevention, friction reduction, self-cleaning surfaces, and micro/macro fluidic channels (Ref 1-5). Metallic superhydrophobic surfaces are of particular interest, as these offer excellent performance when combined with a wide range of metallic materials commonly used in in engineering. However, as the surface energy of metals is inherently high, surface modification is usually necessary to achieve superhydrophobicity. The most commonly used method is to apply a coating made of a low surface energy material such as a macromolecular polymer or organic monolayers. Previous research has revealed that under certain conditions, surfaces that were initially hydrophilic can spontaneously become superhydrophobic (Ref 6-8). This phenomenon is very attractive in the sense that it may have the potential to remove the need for a separate surface modification process, while also reducing the risk of surface peeling. Although the underlying mechanism behind this is quite complex, it is believed to be mostly related to the surface metal oxide; e.g., the adsorption of oxygen on the topmost layer of CuO (Ref 9), partial reduction of CuO (Ref 10), or decomposition of CO2 into carbon by surface oxides (Ref 11, 12). The adsorption of Shaowei Li, Zhida He, Yanjun Zheng, and Changfeng Chen, Department of Materials Science and Engineering, China University of Petroleum, Changping, Beijing 102249, China. Contact e-mails: [email protected] and [email protected].
1574—Volume 24(8) December 2015
organic compounds from the air is also an important factor (Ref 6). Our recent study showed that surfaces of plasmasprayed metallic coatings can transform spontaneously from superhydrophilic to superhydrophobic (Ref 8). It is found that during the hydrophobicity transition, the surface carbon content increased dramatically. The carbon layer can lower the surface energy, which may explain the spontaneous transition of surface wettability. However, the accumulation of surface carbon is not
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