Vanadium dioxide (VO2) exhibits a metal-insulator transition (MIT) that is accompanied by steep changes in electrical and optical properties, making it an important component of device architectures that require facile switching between metal and insulating states. VO2 nanostructures are particularly useful components of such devices, given their unique size-dependent properties and processing capabilities. Here, we show that VO2 nanostructures can be synthesized by chemical transformation of ZnO nanoparticles, which are readily available and serve as morphological templates. Commercially available and colloidally synthesized ZnO nanoparticles react with VOSO4 in water at room temperature to form amorphous VO2, which can be crystallized to the switchable M1 phase of VO2 upon thermal annealing. Experiments probing various particle dimensions, shapes, surface ligands, and reaction parameters suggest that the reaction occurs by depositing VO2 on the ZnO particles, which serve as a sacrificial template. The ZnO-derived VO2 nanostructures exhibit reversible structural transformations between the metallic (R-VO2) and insulating (M1-VO2) phases. Dopants such as Al3+, which modify both the VO2 phase and the MIT properties, can be incorporated. The transition temperature also varies with particle size and reaction parameters. Synthesizing VO2 in solution using ZnO as a sacrificial template provides a potentially scalable route to diverse VO2 nanostructures that exhibit metal-insulator transitions.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Chemistry