Self-assembled gold micro/nanostructure arrays based on superionic conductor RbAg₄I₅ films

Abstract

Herein, we propose a new strategy to fabricate gold (Au) micro/nanostructure arrays by photocatalytic solid-state electrochemical reaction between superionic conductor RbAg4I5 and Au films. The Au and RbAg4I5 films were successively deposited on a clean quartz substrate by vacuum thermal deposition method. A copper microgrid possessing periodic holes 100 μm in diameter was put above the RbAg4I5 film as a mask plate, whereupon irradiation from a 405 nm wavelength laser was used to diffuse gold ions (Au+ ions) into vacant silver sites of RbAg4I5 and transfer Au+ through ion passageways in the RbAg4I5 film. When the laser was turned off, the Au+ ions were easily reduced due to low activity compared to the silver (Ag+) ions. After multiple on/off cycles of the 405 nm laser, the irradiated area of uniform Au film exhibited a periodic structural unit array whose period was the same as that of the mask plate hole array. Atomic force microscope and scanning electron microscope images revealed that a self-assembled needle-like nanostructure array grew perpendicular to the substrate surface inside each circle’s structural unit. The height of the grown nanostructure array increased with laser power density. Raman enhancement of the gold nanostructure array as substrate was detected using Rhodamine 6G (R6G) ethanol solutions as probe molecules. The enhancement effect increased with the height of the grown nanostructure array, and could increase by two orders of magnitude greater than that of unirradiated Au film. This strategy offers a new method for the micro/nanostructure processing of gold and provides microscale-array-mediated surface-enhancement Raman-scattering (SERS) substrates comprising Au nanostructures for application in high-sensitivity spectrum analysis.

Tuning Thermal Catalytic Enhancement in Doped MnO2–Au Nano-Heterojunctions

“…The p-aminothiophenol to p,p′-dimercaptoazobenzene (PATP-to-DMAB) conversions were applied as a proof-of-concept model reaction on MnO 2 −Au hybrid materials, which can be easily monitored by SERS. 28,29 It is worthy to note that most of the previous reports focused on employing SERS to explore photocatalysis, 30,31 while its application in thermal catalysis was scarcely mentioned. In fact, photons are not the only excitation energy source, but thermal energy can also excite electrons from the valence band (VB) to the conduction band (CB) in a semiconductor.…”

“…It is worthy to note that most of the previous reports focused on employing SERS to explore photocatalysis, , while its application in thermal catalysis was scarcely mentioned. In fact, photons are not the only excitation energy source, but thermal energy can also excite electrons from the valence band (VB) to the conduction band (CB) in a semiconductor.…”

Ag Nanoframes Deposited on Au Films Generate Optical Cavities for Surface-Enhanced Raman Scattering

“…In recent years, scientists have centered on developing "hotspot" nanostructures to achieve maximal SERS activity and good consistency. 7 However, the electric field distribution and SERS enhancement effect are sensitive to the gap dimensions and the sample coupling activities for most "hotspot" nanostructures. Therefore, specific sample preparations by professional chemists were needed for SERS detection.…”

Structure, conductivity, and ion emission properties of RbAg4I5 solid electrolyte film prepared by pulsed laser deposition*

“…In 1961, Reuter et al reported SSEs of Ag 3 SI and Ag 3 SBr with the ionic conductivity of 10 −2 S/cm at 25 • C, which breaks the restrictions on the application of SSEs because of their high ionic conductivity ( 10 −6 S/cm at 25 • C). [1] Since then, dozens of different solid state electrolyte materials have been reported, such as Ag + -conducting halide (RbAg 4 I 5 [2] and α-AgI [3] ), oxygen ion-conducting CaO:ZrO 2 , [4] and ThO 2 :Y 2 O 3 , [5] and sodium-conducting β -Al 2 O 3 . [6] There are many advantages of SEs, including high ionic conductivity, wider temperature range for conduction than liquid electrolyte and easy miniaturization owing to the solid form, and the dominating charge carriers in SSEs being ions with the insignificant electronic conductivity.…”