Ceria nanorods

Zhou KB, Wang X, Sun XM, Peng Q, Li YD. Enhanced catalytic activity of ceria nanorods from well-defined reactive crystal planes. 7. Catal. 2005 229 206-212. 

Liang S, Veser G. Mixed lanthana/ceria nanorod-supported gold catalysts for water-gas-shift. Catal Lett 2012 142 936. 

Figure 5.12 Atomistic models and HRTEM images of ceria nanorods, (a) and (b) Model CeOj nanorods, which extend along [110] and (b), respective, (c) Nanorod with twin-grain boundaries the atomistic structure of the grain-boundary region is shown enlarged in the inset. HRTEM images of nanorods with [110] and [211] growth directions are shown in (d) and (e), respectively, (a)-(c) Reprinted with permission from Sayle et al. Copyright 2007 American Chemical Society, (d), (e) Reprinted with permission from Du et all Copyright 2007 American Chemical Society.

Similarly, one can consider the reactivity of ceria nanorods. Here, the simulations revealed that the growth directions of ceria nanorods are important with respect to reactivity as rods with different growth... 

Jin and co-workers obtained 1.5-nm ultra-thin ceria nanorods from a cerium stearate precursor. The reaction was carried up at 270°C in 1-octadecene with the addition of 1-octadecanol. The authors ascribed the formation of nanorods to the oriented attachment of ultra-small ceria nanocrystals grown in the initial stage of the reaction. 

Gataluminescence (GTL) is the chemiluminescence produced during catalytic oxidation reactions. Ye et al studied GTL and the catalytic oxidation reactions of ethanol on nanosized Gei r,02 materials. The ceria-rich solid solutions (x= 0.05-0.25) showed high GTL activity at 220°G and were considered to be efficient low-temperature GTL sensors for ethanol. The GTL intensity of ethanol oxidation was closely related to the steady-state activity of the Gei jZr 02 catalysts in the oxidative dehydrogenation of ethanol. Xuan et al studied the GTL of GS2 on the surface of ceria nanorods, nanocubes, and... 

Figure 8.18 TEM images of ceria nanorods prepared by the sonochemical method. Reprinted with permission from Zhang et Copyright 2007 the American Chemical Society.

These new nanomaterials mentioned above not only appear preeminent in catalytic activity but also were recendy proved superior to reveal the surface dependence of ceria in catalytic CO oxidation. Zhou et al., by comparing the one-dimensional (ID) nanorods and the nanoparticles of ceria, proposed that throughout the experimental temperature range, the predominantly exposed (001) and (110) facets of ID ceria nanorod give higher CO conversion rate than the predominandy exposed (111) facet of ceria nanoparticles (Zhou et al., 2005). Ane et al. (2005) reported similar results by manipulating the exposed planes of poly crystalline ceria powders. 

Sayle DC, Feng XD, Ding Y et al (2007) Simulating synthesis ceria nanosphere self-assembly into nanorods and framework arcMtectuies. J Am Chem Soc 129(25) 7924—7935... 

The Hydrothermal process has been a well-known procedure for material synthesis since the 1970s. It begins with an aqueous mixture of soluble metal salt (metal and/or metal-organic) precursors, then the solution is placed in an autoclave at a high temperature (between 100°C and 300°C) and under relatively high pressure (> 1 atm) conditions. ZnO nanorods, - CuO, ceria, titania and Mn02 have been prepared by using wet-chemical hydrothermal approaches. 

Idakiev et al. [137] reported mesoporous ceria and nanorods Ce02 for the Au catalysts for WGSR. Both mesoporous- and nanorod-supported catalysts exhibit higher activity than regular Au/Ce02. Of the mesoporous- and nanorod-supported catalysts, mesoporous-supported catalyst exhibited higher activity. 

The prediction that Ce02(331) can result in a catalyti-cally active surface is appealing although at present the interest is mainly academic. Recent advances in the synthesis of ceria nanoparticles or nanorods with defined crystal faces [63, 64] will perhaps allow to experimentally verify this prediction and may open the way toward a new family of designed catalysts. 

Yan and co-workers used Ce(III) precursors to react with NaOH using the hydrothermal method. The mechanism was considered to be that hexagonal phase Ce(OH)j nanorods were initially formed in the reacuon, followed by oxidization to the final ceria products with a rod-shape. 

Ding, Sun, and co-workers used urea as a precipitant to obtain Ce(0H)C03 nanorods as intermediate products. After treatment with NaOH at different concentrations, two kinds of ceria nanotubes were obtained through an interface reaction involving Ce(OH)COa and Ce(OH)3 as intermediates, respectively. These methods for synthesizing ceria nanotubes are a result of the Kirkendall effect, involving the dissolution and oxidization of Ce(III) followed by precipitation of Ce(fV). ... 

Another kind of ID ceria nanostructure is the spindle. Zheng and co-workers described a hydrothermal method to obtain spindles. Urea was used as a precipitant and the reaction time was relatively shorter than for nanotubes. Zhang, Shi and co-workers also described a method to prepare ceria nanospindles. Ce(III) was precipitated by urea in the presence of glycerin. Ce(0H)G03 was realized as intermediate and the mechanism involved the assembly of small particles assisted by glycerin molecules adsorbed on the surface of the parti-cles. ° Sun et al used a similar solvothermal method to assemble shutde-like ceria nanomaterials from nanorods. Zhang, Tong and co-workers described the synthesis of bowknot-like ceria bundles assembled from nanorods obtained via a hydrothermal reaction. ... 

At the same time, for the model catalysts, many attempts have been devoted to exploring the pure ceria as a catalyst without introducing any other element, and nanomaterials of pure ceria, including nanorods, nanoparticles, nanocubes, nanotubes, nanoplates, nanobeads, and nanowires have been prepared and studied (Bhatta et al., 2012 Hirst et al., 2009 Loschen et al., 2008 Tana et al., 2009 Wu et al., 2012 Xu et al., 2010). Lin et al. have thoroughly summarized some progresses in this field... 

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