Suchergebnisse

Hydrogen is the key element to accomplish a carbon-free based economy. Here, the first evidence of plasmonic gallium (Ga) nanoantennas is provided as nanoreactors supported on sapphire (α-Al2O3) acting as direct plasmon-enhanced photocatalyst for hydrogen sensing, storage, and spillover. The role of plasmon-catalyzed electron transfer between hydrogen and plasmonic Ga nanoparticle in the activation of those processes is highlighted, as opposed to conventional refractive index-change-based sensing. This study reveals that, while temperature selectively operates those various processes, longitudinal (LO-LSPR) and transverse (TO-LSPR) localized surface plasmon resonances of supported Ga nanoparticles open selectivity of localized reaction pathways at specific sites corresponding to the electromagnetic hot-spots. Specifically, the TO-LSPR couples light into the surface dissociative adsorption of hydrogen and formation of hydrides, whereas the LO-LSPR activates heterogeneous reactions at the interface with the support, that is, hydrogen spillover into α-Al2O3 and reverse-oxygen spillover from α-Al2O3. This Ga-based plasmon-catalytic platform expands the application of supported plasmon-catalysis to hydrogen technologies, including reversible fast hydrogen sensing in a timescale of a few seconds with a limit of detection as low as 5 ppm and in a broad temperature range from room-temperature up to 600 °C while remaining stable and reusable over an extended period of time. ; The authors thank all of the students and colleagues in their groups who were actively involved with nanoparticles research. M.L., Y.G., and F.M. have received funding from the European Union's Horizon 2020 Research and Innovation Program under Grant Agreement No. 899598—PHEMTRONICS. F.M. acknowledges MINECO (Spanish Ministry of Economy and Competitiveness, project PGC2018-096649-B-100).

Structural color emerges from the interaction of light with structured matter when its dimension is comparable to the incident wavelength. The reflected color can be switched by controlling such interaction with materials whose properties can be changed through external stimuli such as electrical, optical, or thermal excitation. In this research, a molybdenum oxide (MoOx) reflective grating to get a switchable on/off subpixel is designed and analyzed. The design is based on subpixel on and off states that could be controlled through the oxidation degree of MoOx. A suitable combination of three of these subpixels, optimized to get a control of primary colors, red, green, and blue, can lead to a pixel which can cover a wide range of colors in the color space for reflective display applications. ; The authors received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 899598—PHEMTRONICS.

Interest in gallium chalcogenides, i.e., gallium sulfide (GaS) and gallium selenide (GaSe), is growing rapidly due to its layered structure compatible with the fabrication of very thin layers by mechanical exfoliation and its wide band gap desirable for the design and fabrication of visible-UV optoelectronic devices. It is well known that the properties of these materials depend on their thickness; therefore, a facile and fast method is needed to infer the thickness of layered GaS and GaSe. Here, we report and validate a colorimetric method based on optical imaging for the quick and reliable quantitative determination of the thickness of exfoliated GaS and GaSe layers although it can be extended to other layered systems. For the validation of the method, the colorimetric computational estimate of the thickness is compared to the value obtained by atomic force microscopy. Further simulation of GaS and GaSe layers on different substrates of interest for different technological applications is provided as a quick guide for the rapid and reliable thickness determination of GaS and GaSe layers on various substrates. ; Funding. European Union's Horizon 2020 research and innovation program (No 899598 – PHEMTRONICS).

We report unexpected enhancements of the magneto-optical effect in ferromagnetic Permalloy disks of diameter D < 400 nm. The effect becomes increasingly pronounced for smaller D, reaching more than a 100% enhancement for D ¼ 100 nm samples. By means of experiments and simulations, the origin of this effect is identified as a nanoscale ring-shaped region at the disk edges, in which the magneto-optically induced electric polarization is enhanced. This leads to a modification of the electromagnetic near fields and causes the enhanced magneto-optical excitation, independent from any optical resonance. ; We acknowledge funding from the Basque Government (Program No. PI2012-47) and the Spanish Government (Project No.MAT2012-36844).Work at the Universidad de Cantabria has been supported by MICINN under Project No. FIS2013-45854-P.