Nanometric Al₂O₃ Layers Obtained from Liquid Metals: Implications for Sensing Devices

Abstract

Nanomaterials, and in particular nanolayers, are of importance in the fields of electronics, biomedical devices, and sensors. It is thus crucial to develop sustainable ways to obtain these nanomaterials and fully characterize their potential in view of these applications. In this work, the microstructure and chemical composition of Al2O3 oxide layers obtained by exfoliation from liquid metals are investigated. The method allows nanometric oxide layers to be obtained at low temperatures, without excessive waste, as the base alloy can be reused in the process. Metal oxide layers were deposited on different substrates, including glass, Si, and SiO2. The Al2O3 oxide was obtained from two liquid metal compositions (GaAleut and Ga-30 at% Al) in order to understand the influence of the composition of the base alloy on the final product. The contact angle between the alloys and substrates was measured using the static sessile drop method. The layers were characterized using AFM and TEM. Moreover, the chemical composition was assessed using XPS. The samples consist of α-Al2O3 nanocrystallites embedded in an amorphous oxide layer, with ∼20 to 30 nm nanodroplets of metallic gallium. The nanometric oxide layers obtained within the frame of this work have the potential to be used in gas sensors upon further research.

Room-Temperature Preparation of Large-Area Transparent Two-Dimensional ZnO-Doped Ga2O3 Nanostructure-Based Layers: Implications for Optoelectronic Nanodevices

“…26,27 Furthermore, liquid Ga can also act as the parent metal to form a low-melting liquid Ga alloy for the preparation of other metal oxides due to the elemental segregation and preferential oxidation. Dobosz et al 28 discovered that an ultrathin 2D alumina nanocrystal film could be prepared from a Ga−Al binary alloy due to the stronger oxidizability of the Al element than the Ga element. In a similar way, 2D HfO 2 and Gd 2 O 3 layers could also be obtained from quaternary alloys of Hfcontaining galinstan and Gd-containing galinstan.…”

Recent progress in liquid metal printing and its applications

“…16 (e) Bright-field images of GaAl eut at room temperature, GaAl eut at 500 °C, and Ga-30 at% Al at 500 °C. 14 (f) Multilayer carbon nanotubes/gold nanoparticles composites based on gallium-based liquid metal for electrochemical biosensing. 15 (g) Bio-elastomer based liquid metal filled magnetorheological elastomers.…”

“…This nano oxide layer obtained from two LM components (including Ga–Al eut and Ga-30 at% Al) was applied to gas sensors. 14 It allows deposition at low temperatures and produces eco-friendly nanomaterials with minimal consumption. The prepared metal oxide nanomaterials have significance for sensors and electronic devices.…”

“…12 (d) Reduction of interfacial graphene oxide by liquid metals 16. (e) Bright-field images of GaAl eut at room temperature, GaAl eut at 500 °C, and Ga-30 at% Al at 500 °C 14. (f) Multilayer carbon nanotubes/gold nanoparticles composites based on gallium-based liquid metal for electrochemical biosensing 15.…”