Bottom-up growth of high-quality BiOCl twisted homostructures via a precursor regulation strategy

Twisted stacking-induced moiré superlattice of two-dimensional (2D) materials have aroused surging interest due to their novel properties and promising applications in quantum technologies. However, problems such as unavoidable interfacial contamination in the prevailing mechanically transferred method, and limited members of 2D materials for constructing twisted homostructures/heterostructures impede the advance of 2D moiré superlattice. Here, bottom-up growth of high-quality bismuth oxychloride twisted homostructures (BiOCl THS) is achieved by a precursor-regulated chemical vapor deposition (CVD) method. In contrast to the conventional screw-dislocation-driven growth of spiral-like nanosheets, the as-prepared BiOCl THSs show a wide range of twist angles and large lateral sizes. A unique secondary twisted nucleation growth mechanism is revealed by multiple characterizations and theoretical calculations. It is demonstrated that the adsorption of polar H₂O molecule on BiOCl can lead to a stable nucleation with rotation angles. Furthermore, benefitting from the bottom-up growth of the twisted homostructures, clear moiré patterns and moiré potential induced variation of interlayer coupling and exciton resonances were observed in the BiOCl THS. Our work provides a promising strategy for controllable preparation of high-quality 2D moiré superlattice.