Ultrathin two-dimensional β-In2S3 nanocrystals: oriented-attachment growth controlled by metal ions and photoelectrochemical properties

Abstract

Ultrathin two-dimensional (2D) semiconductor nanocrystals have attracted much attention of late due to their attractive functional properties. Concurrently, oriented-attachment (OA) growth has been considered as an important growth theory for the construction of various nanocrystals, especially ultrathin 2D nanocrystals. However, all the OA growth procedures reported in the preparation of nanocrystals have been driven by organic ligand molecules so far. In this paper, we report for the first time that a metal ion controlled OA growth to synthesize semiconductor nanocrystals: 2D β-In₂S₃ nanobelts and nanoflakes with ∼2 nm thickness can be achieved via OA controlled by Ca²⁺ and Al³⁺, respectively. Note that Ca²⁺ and Al³⁺ are not incorporated into the crystal lattice structure of β-In₂S₃. β-In₂S₃ nanobelts and nanoflakes show step-like absorptions in UV-visible spectra. Furthermore, β-In₂S₃ nanoflakes exhibit the most outstanding photoelectrochemical activity when compared with β-In₂S₃ nanoparticles and nanobelts.