Liquid Metal Printed Zinc Tin Composite Oxide Nanosheets: A Platform for Multifunctional Sensing at Room Temperature

Liquid metal (LM) alloys have attracted significant interest as exceptional functional materials due to their wide range of applications. Although significant theoretical advancements have been made, the experimental investigation of surface oxides in complex metal alloys remains largely unexplored. This study investigates the formation of surface oxide in eutectic zinc (Zn)-tin (Sn) alloy to increase the understanding of composite metal oxides and enable new technological applications. The study reveals the formation of zinc tin composite metal oxide (ZTCMO) with ≈82.7 at% ZnO and ≈17.3 at% SnO₂ by utilizing the liquid metal-based van der Waals (vdW) printing approach. Structural characterizations confirm the formation of highly crystalline ZTCMO nanosheets with a wide bandgap of 3.3 eV. The ultrathin nanosheets demonstrate their practicality as an ultraviolet (UV) optical sensor with maximum responsivities of 3.84 A W^-1 at 285 nm and 1.31 A W^-1 at 365 nm, achieved at a low power density of 0.1 mW cm^-2. Additionally, ZTCMO nanosheets exhibit excellent room temperature ammonia (NH₃) gas sensing with high sensitivity and selectivity, detecting concentrations as low as 50 parts per million under UV light illumination. These findings highlight the potential of composite metal oxide-based devices with the capability of multifunctional sensing.