Self-Assembled Porous 3D Flowerlike β-In₂S₃ Structures:  Synthesis, Characterization, and Optical Properties

Uniform 3D flowerlike architectures of β-In2S3 assembled with nanoflakes were synthesized in ultrahigh yield via a hydrothermal method between indium chloride (InCl3·4H2O) and l-cysteine. After annealing at 400 °C, high-crystalline β-In2S3 was prepared and inherited the morphology of In2S3 before annealing. The combination of In3+ and l-cysteine in the reaction solution produced the complex, which served as both the indium source and the sulfur source. It was found that the pH of the mixed solution, l-cysteine, and the molar ratio of the reactants played important roles in controlling the final structures. The possible growth mechanism for the formation of 3D flowerlike architectures was preliminarily investigated on the basis of experimental results. The porous In2S3 possessed a specific surface area of 78 m2/g and a bimodal distribution of pore sizes corresponding to the size of pores resulting from the self-assembled structures with flakes. The optical properties of In2S3 were also investigated by ultraviolet and visible (UV−vis) spectroscopy, which indicated that In2S3 was a mid band gap semiconductor.