Multi-Functional Atomically Thin Oxides from Bismuth Liquid Metal

Atomically thin, mechanically flexible, memory-functional, and power-generating crystals play a crucial role in the technological advancement of portable devices. However, the adoption of these crystals in such technologies is sometimes impeded by expensive and laborious synthesis methods, as well as the need for large-scale, mechanically stable, and air-stable materials. Here, an instant-in-air liquid metal printing process utilizing liquid bismuth (Bi) is presented, forming naturally occurring, air-stable, atomically thin, mechanically flexible nanogenerators and ferroelectric oxides. Despite the centrosymmetric nature of the monoclinic P21/c system of achieved α-Bi₂O_3-δ the high kinetics of liquid metal synthesis leads to the formation of vacancies that disrupt the symmetry which is confirmed by density functional theory (DFT) calculations. The polarization switching is measured and utilized for ferroelectric nanopatterning. The exceptional attributes of these atomically thin multifunctional stable oxides, including piezoelectricity, mechanical flexibility, and polarizability, present significant opportunities for developing nano-components that can be seamlessly integrated into a wide range of devices.