Nanometer-Thick Al₂O₃ Layers on Ag–Al Nanostructures as Conductive Electrodes

Abstract

Silver (Ag) nanostructures are active functional platforms for catalysts, optical sensors, and transparent conductive networks with outstanding performance but present poor stability depending on their chemical, mechanical, or thermal surroundings. Doping with other elements and passivation with a chemically inert coating of a Ag nanostructure are proven to be efficient in enhancing the stability, while both methods have drawbacks such as cost and sacrifice of the on-demand properties. Here, we present a self-passivated Ag−Al nanostructure with a precisely controlled coating thickness, taking advantage of the intrinsic high conductivity and chemical reducibility of aluminum at the same time, fabricated by oblique angle codeposition of Ag−Al nanostructures followed by postannealing under mild conditions. With the nanometer-thick coating confirmed by transmission electron microscope (TEM) observations, surface-enhanced Raman scattering (SERS) measurements were successfully utilized to further demonstrate the quality of the in situ grown aluminum oxide (Al 2 O 3 ) layer, including the thickness, coating integrity, and chemical stability. In addition, a mechanically robust nanostructure as well as an ultrathin conductive electrode ∼10 nm in thickness was enabled by dilute doping of Al into the Ag matrix. Interestingly, a bipolar change in the Ag−Al/MoS 2 /Ag−Al device after annealing was achieved. Further observation revealed that the Al 2 O 3 layer grew on top of the Ag−Al alloys. The methods we developed require dilute doping of Al into a Ag matrix and mild processing conditions, yet precise interface thickness control and pronounced property enhancement are achieved, all of which pave the way for the practical application of Ag nanostructures in optical sensors and integrated circuits. KEYWORDS: Ag−Al alloy, low-temperature annealing, in situ grown Al 2 O 3 layer, oblique angle deposition, ultrathin conductive electrode

Induction vacuum swing adsorption over magnetic sorbent monoliths and extrudates for ethylene/ethane separation

“…Regarding Fe 20 /13X-M, the measured BET surface area and total pore volume were found to be 603.4 m 2 /g and 0.268 cm 3 /g, respectively. These values were slightly lower than those reported in our previous work, 19 where we observed surface areas of 632 m 2 /g and total pore volumes of 0.332 cm 3…”

“…1,2 The current methods of producing ethylene, such as paraffin dehydrogenation or steam cracking, result in a mixture of ethane (C 2 H 6 ) and ethylene in the final product. 3,4 To separate these two gases, cryogenic high-pressure distillation process is a well-established industrial separation technology, which is costly and energy-intensive due to their similar volatilities and sizes. 5,6 Approximately 10-20% of the total energy consumption is utilized in the cryogenic distillation process to achieve their separation.…”