Supersaturation-controlled synthesis of diverse In2O3 morphologies and their shape-dependent sensing performance

Abstract

The precisely controlled synthesis of a specific morphology is proved to be highly effective for enhancing sensing performance of functional micro- and nano-materials. Thus, a comprehensive understanding of the effect of synthesis conditions on morphology evolution is of great importance. In this paper, by using In₂O₃ as an example, we demonstrate the great effect of supersaturation on the morphology evolution during the growth process. Under vapour-phase synthesis, by varying positions of product collection, the amount of the starting materials, and reaction temperatures, a continuous two-step route consisting of ammonolysis and re-oxidation processes was developed for the morphology evolution of several kinds of In₂O₃, including octahedron strings, nanowires, crystal chains, lollipop-like structures, and particles. The controlled supersaturation of the In₂O₃ vapour was eventually proved to be a decisive factor for the formation of various In₂O₃ morphologies. Furthermore, we evaluated the gas-sensing properties of the three kinds of one-pot synthesized In₂O₃, indicating a shape-dependent relationship with sensing performance. The present work not only offers a unique strategy to control supersaturation in vapour-phase synthesis, but also provides an opportunity to deeply understand the morphology-dependent sensing performance.