Ligand-Assisted Solid-State Transformation of Nanoparticles

• Published in: Chemistry of materials 2020-04, Vol.32 (7), p.3271-3277
• Main Authors: Li, Bo, Chen, Jinxing, Han, Lili, Bai, Yaocai, Fan, Qingsong, Wu, Chaolumen, Wang, Xiaojing, Lee, Michael, Xin, Huolin L, Han, Zhiwu, Yin, Yadong
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.0c00573

Thermal treatment is generally a desirable process to improve the properties of nanomaterials, which however often leads to undesirable problems such as aggregation and shape deformation. Here, we overcome this challenge by developing a ligand-assisted calcination strategy for shape-preserved chemical transformation of nanostructures. While capping ligands are often thought to be effective in solution phase synthesis, we show that their presence during high-temperature calcination not only maintains the overall particle morphology but also offers the possibility of effective creation of controllable porosity in metal oxide nanostructures. We demonstrate a particularly elegant example of this strategy, which involves the chemical conversion of β-FeOOH ellipsoids into porous α-Fe2O3 and magnetic Fe3O4 ellipsoids with morphological preservation and excellent solution dispersity via stabilization with strong coordinating capping ligands. The ligand-assisted solid-state conversion strategy represents a general self-templating method for creating nanomaterials, as confirmed by its successful application to a wide range of morphologies (ellipsoids, rods, cubes, and plates) and compositions (hydroxides and metal–organic frameworks).