Liquid-Metal-Assisted Deposition and Patterning of Molybdenum Dioxide at Low Temperature

Molybdenum dioxide (MoO₂), considering its near-metallic conductivity and surface plasmonic properties, is a great material for electronics, energy storage devices and biosensing. Yet to this day, room-temperature synthesis of large area MoO₂, which allows deposition on arbitrary substrates, has remained a challenge. Due to their reactive interfaces and specific solubility conditions, gallium-based liquid metal alloys offer unique opportunities for synthesizing materials that can meet these challenges. Herein, a substrate-independent liquid metal-based method for the room temperature deposition and patterning of MoO₂ is presented. By introducing a molybdate precursor to the surrounding of a eutectic gallium-indium alloy droplet, a uniform layer of hydrated molybdenum oxide (H₂MoO₃) is formed at the interface. This layer is then exfoliated and transferred onto a desired substrate. Utilizing the transferred H₂MoO₃ layer, a laser-writing technique is developed which selectively transforms this H₂MoO₃ into crystalline MoO₂ and produces electrically conductive MoO₂ patterns at room temperature. The electrical conductivity and plasmonic properties of the MoO₂ are analyzed and demonstrated. The presented metal oxide room-temperature deposition and patterning method can find many applications in optoelectronics, sensing, and energy industries.