Simple and efficient treatment for producing porous nanostructures using gas-solid reactions

A convenient gas-solid reaction route has been developed for the synthesis of porous nanostructures. Pre-obtained nanostructures were heat-treated under a certain atmosphere, and an unstable intermediate was generated in situ and subsequently decomposed, giving rise to porous nanostructures while retaining the morphologies of the raw materials. With this strategy, γ-Al ₂O₃ porous nanowires with a pore size of about 3.5 nm and a high thermal stability of up to 1000 °C were synthesized simply by treating AlN nanowires in air at elevated temperature. The porous γ-Al₂O₃ products were well characterized, and the formation mechanism is discussed accordingly. The unstable intermediate is crucial for the formation of porous nanostructures. This synthesis strategy was also successfully extended to the preparation of In₂O₃ porous nanostructures. Both the simple and scalable preparation process and the good thermal stability of the porous products resulting from the high-temperature experience make this gas-solid reaction route very attractive for wide potential applications.