Solvothermal Synthesis Routes to Substituted Cerium Dioxide Materials

Abstract

We review the solution-based synthesis routes to cerium oxide materials where one or more elements are included in place of a proportion of the cerium, i.e., substitution of cerium is performed. The focus is on the solvothermal method, where reagents are heated above the boiling point of the solvent to induce crystallisation directly from the solution. This yields unusual compositions with crystal morphology often on the nanoscale. Chemical elements from all parts of the periodic table are considered, from transition metals to main group elements and the rare earths, including isovalent and aliovalent cations, and surveyed using the literature published in the past ten years. We illustrate the versatility of this synthesis method to allow the formation of functional materials with applications in contemporary applications such as heterogeneous catalysis, electrodes for solid oxide fuel cells, photocatalysis, luminescence and biomedicine. We pick out emerging trends towards control of crystal habit by use of non-aqueous solvents and solution additives and identify challenges still remaining, including in detailed structural characterisation, the understanding of crystallisation mechanisms and the scale-up of synthesis.

In situ generation of H2O2 using CaO2 as peroxide storage depot for haloperoxidase mimicry with surface-tailored Bi-doped mesoporous CeO2 nanozymes

“…Fig. 1D shows the powder X-ray diffraction patterns (PXRD) of BiCe-1.5 h, BiCe-2.0 h and BiCe-2.5 h. The diffraction patterns indicate the formation of a substitutional phase with cubic cerianite structure (space group Fm 3̄ m , red ticks) in harmony with previous studies by Walton, 47 Iversen 48 and coworkers. All reflections are shifted to slightly smaller Q values, indicating a lattice expansion due to Bi 3+ substitution.…”

“…37,38 Bi 3+ can replace Ce 4+depending on the preparation methodto an extent of 25-40%. 38,47,48 The charge/radius ratio condition for trivalent metals significantly limits the choice of dopants. For example, since the coordination of many 3d metals such as Fe 3+ (or main group metals such as Al 3+ ) is not compatible with the coordination in the fluorite structure, there are only a few candidates for metal substitution.…”

Oxygen Vacancy Induced Strong Metal-Support Interactions on Ni/Ce0.8Zr0.2O2 Nanorod Catalysts for Promoting Steam Reforming of Toluene: Experimental and Computational Studies

“…Therefore, the abovementioned excellent properties of CeO 2 could be further enhanced. Besides, compared with CeO 2 , Ce x Zr 1– x O 2 exhibited better sintering resistance at high temperatures …”

“…Thereinto, CeO 2 has excellent redox characteristics as well as oxygen storage and transmission due to the existence of oxygen vacancies (OVs) . For steam reforming reactions, OVs on the Ce-based support provide sites for the dissociation of H 2 O to generate reactive oxygen species, and these oxygen species could be conveniently delivered to the surface of the active metal (Ni), promoting the reforming reaction and carbon deposition removal. , When a small amount of Zr is doped into CeO 2 to form ceria–zirconia solid solution (Ce x Zr 1– x O 2 ), more OVs would be produced due to the local distortion of the crystalline structure . Therefore, the abovementioned excellent properties of CeO 2 could be further enhanced.…”

One-Step Low Temperature Synthesis of CeO2 Nanoparticles Stabilized by Carboxymethylcellulose

“…Many chemical methods for the synthesis of nanoceria are reported in the literature. Precipitation methods such as co-precipitation, chemical precipitation, microwave, sonochemical, hydrothermal, reverse-co-precipitation, and microwave–hydrothermal methods are basic procedures of synthesis [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. The key disadvantage of these methods for obtaining cerium-containing nanoparticles is the requirement to conduct the reactions at high temperatures.…”