One-step room temperature rapid synthesis of Cu sub(2)Se nanostructures, phase transformation, and formation of p-Cu sub(2)Se/p-Cu sub(3)Se sub(2) heterojunctions

A tetragonal Cu sub(2)Se film containing a well-aligned nanosheet array with scattered 3D flower-like microstructures on top was synthesized for the first time by a rapid one-step low-energy route, which is beneficial for large scale industrial production due to savings in energy, time and expensive instruments. Phase transformation occurred after scraping the film from the Cu substrate, and heating or grinding the Cu sub(2)Se powder in air. The Cu sub(2)Se/Cu sub(3)Se sub(2) composite containing p-Cu sub(2)Se/p-Cu sub(3)Se sub(2) heterojunctions was obtained by simply calcining the Cu sub(2)Se in air at 300 degree C for 3 h. The composite has enhanced gas sensing properties towards acetone gas and a lower band gap energy compared to Cu sub(2)Se.