Deposition of Vertically Aligned Ag/Ag₂S Nanoflakes on EGaIn Particles for Humidity Sensing

Abstract

Liquid metals, which possess both good electrical conductivity and liquid-like processability, have drawn much attention recently. They are also capable of acting as synthesis templates to guide the deposition of other functional materials. Herein, through an in-situ galvanic replacement reaction assisted by ultrasonication, core-shell EGaIn/Ag particles composed of EGaIn cores and vertically aligned Ag nanoflakes as shells were prepared; they were further sulfurized to yield ternary EGaIn/Ag/Ag 2 S core-shell compo-site particles. A humidity sensor based on EGaIn/Ag/Ag 2 S particles showed much higher sensing response than EGaIn and EGaIn/Ag. Such superior performance could be attributed to the n-type semiconducting character of Ag 2 S allowing it to receive electrons from water molecules at low humidity, and its highly hydrophilic surface allowing it to absorb more water molecules at higher humidity so as to enable the formation of ion-conductive paths.

Enabling High-Performance Pressure and Proximity Dual-Mode Sensing with EGaIn/Ag/ZnO Egg-Shell Ternary Composite Particles

“…The energy dispersive spectroscopy (EDS) mapping of an eggshell particle shows the distribution of Ag, Zn, In, and Ga, where In was located in the center of the sphere and Zn, Ga, and Ag were located mainly at the shell (Figures 1h and S4). In the high-resolution X-ray photoelectron spectroscopy (XPS) (Figure S5), Ga 3+ , In 0 , Ag 0 , and Zn 2+ species were identified, 11,27 consistent with the composition. Various EGaIn-based materials, including EGaIn (Figure S1), EGaIn/Ag (Figure S2), EGaIn/ZnO (Figure S6), and EGaIn/Ag/ZnO, were fabricated into pressure sensors.…”

“…As shown in Figure a, we first prepared EGaIn/Ag composite spheres by ultrasonicating EGaIn droplets in the presence of AgNO 3 aqueous solution based on the modification of a previously reported method . These spheres were 100 to 800 nm in size, as shown in the SEM image in Figure S1a.…”

“…In recent years, EGaIn alloys have been integrated with other nanomaterials to achieve added functionalities. Examples include core-shell composites of EGaIn and fluorescent materials such as YVO 4 :Eu 3+ for electrochromic application, EGaIn/GO particle composite for electromagnetic interference shielding, and EGaIn/Ag/Ag 2 S composite for humidity sensing . Although considerable efforts have been made in the functionalization of EGaIn-based composites, fine control over both composition and morphology remains a great challenge.…”

Recent progress in eutectic gallium indium (EGaIn): surface modification and applications

“…7d). 75 Because of the superior qualities of the semiconductor material Ag 2 S, the EGaIn/Ag/Ag 2 S-based humidity sensor performs exceptionally well. Ag 2 S has the capacity to take in airborne water molecules and receive electrons from them.…”

Vertically-grown Ag nanoplates on SeZnO3 nanosheets for an enhanced pressure sensing performance

“…23,24 In addition, the extra Ag 3d spectrum of the nanocomposite showed two peaks at 368.19 eV (Ag 3d 5/2 ) and 374.19 (Ag 3d 3/2 ), which can be assigned to the Ag 0 state, further proving that Ag + was successfully reduced to Ag 0 by the photo-reduction method. 25…”