Targeted Synthesis of Nanostructured Oxide Materials

Abstract

Morphology control is a key challenge in the straightforward hydrothermal production of technologically relevant anisotropic oxide materials. The use of readily available ionic additives as growth modifiers is discussed and compared for molybdenum- and tungsten oxide-based systems, and it is extended to the formation of ternary W/Mo-oxides. Generally, the one-step hydrothermal synthesis of ternary and higher oxides is an important goal, because their properties often outperform those of the binary oxides. This holds especially for the Bi₂O₃-MoO₃-VO_x (BIMOVOx) system as a rich source of new materials. We present a new solution-based approach to α-Bi₂O₃ nanobelts starting from commercial Bi₂O₃ and K₂SO₄ as a key step on the way to anisotropic BIMOVOx-oxides. This hydrothermal process is an illustrative example of highly selective and efficient morphology control through an inorganic additive. As mechanistic and kinetic studies are crucial for the design of complex oxide nanomaterials, the Bi₂O₃-K₂SO₄ system is compared to our previous studies on Mo-, W- and V-oxides with respect to its hydrothermal parameter window and robustness.