Lim Alvin M H, Zeng Hua Chun
Department of Chemical and Biomolecular Engineering, Faculty of Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore.
ACS Appl Mater Interfaces. 2021 May 5;13(17):20501-20510. doi: 10.1021/acsami.1c01320. Epub 2021 Apr 23.
Cerium(IV) oxide (CeO), or ceria, is one of the most abundant rare-earth materials that has been extensively investigated for its catalytic properties over the past two decades. However, due to the global scarcity and increasing cost of rare-earth materials, efficient utilization of this class of materials poses a challenging issue for the materials research community. Thus, this work is directed toward an exploration of making ultrathin hollow ceria or other rare-earth metal oxides and mixed rare-earth oxides in general. Such a hollow morphology appears to be attractive, especially when the thickness is trimmed to its limit, so that it can be viewed as a two-dimensional sheet of organized nanoscale crystallites, while remaining three-dimensional spatially. This ensures that both inner and outer shell surfaces can be better utilized in catalytic reactions if the polycrystalline sphere is further endowed with mesoporosity. Herein, we have devised our novel synthetic protocol for making ultrathin mesoporous hollow spheres of ceria or other desired rare-earth oxides with a tunable shell thickness in the region of 10 to 40 nm. Our ceria ultrathin hollow spheres are catalytically active and outperform other reported similar nanostructured ceria for the oxidation reaction of carbon monoxide in terms of fuller utilization of cerium. The versatility of this approach has also been extended to fabricating singular or multicomponent rare-earth metal oxides with the same ultrathin hollow morphology and structural uniformity. Therefore, this approach holds good promise for better utilization of rare-earth metal elements across their various technological applications, not ignoring nano-safety considerations.
二氧化铈（CeO₂），即氧化铈，是最丰富的稀土材料之一，在过去二十年中因其催化性能而受到广泛研究。然而，由于稀土材料的全球稀缺性和成本不断增加，这类材料的高效利用对材料研究界来说是一个具有挑战性的问题。因此，这项工作旨在探索制备超薄中空氧化铈或其他稀土金属氧化物以及一般的混合稀土氧化物。这种中空形态似乎很有吸引力，特别是当厚度被削减到极限时，这样它就可以被视为由纳米级微晶组成的二维薄片，同时在空间上保持三维结构。如果多晶球体进一步具有介孔性，这将确保内、外表面在催化反应中都能得到更好的利用。在此，我们设计了一种新颖的合成方法，用于制备具有10至40纳米可调壳层厚度的超薄介孔中空二氧化铈或其他所需稀土氧化物球体。我们的二氧化铈超薄中空球体具有催化活性，在铈的更充分利用方面，其一氧化碳氧化反应性能优于其他报道的类似纳米结构的二氧化铈。这种方法的通用性还扩展到制造具有相同超薄中空形态和结构均匀性的单一或多组分稀土金属氧化物。因此，这种方法在稀土金属元素的各种技术应用中具有更好利用的良好前景，同时也兼顾了纳米安全性考虑。
