Metasurface-driven optical encryption devices have attracted much attention. Here, we propose a dual-band vectorial metahologram in the visible and ultraviolet (UV) regimes for optical encryption. Nine polarization-encoded vectorial holograms are observed under UV laser illumination, while another independent hologram appears under visible laser illumination. The proposed engineered silicon nitride, which is transparent in UV, is employed to demonstrate the UV hologram. Nine holographic images for different polarization states are encoded using a pixelated metasurface. The dual-band metahologram is experimentally implemented by stacking the individual metasurfaces that operate in the UV and visible. The visible hologram can be decrypted to provide the first key, a polarization state, which is used to decode the password hidden in the UV vectorial hologram through the use of an analyzer. Considering the property of UV to be invisible to the naked eye, the multiple polarization channels of the vectorial hologram, and the dual-band decoupling, the demonstrated dual-band vectorial hologram device could be applied in various high-security and anticounterfeiting applications.

Fixed-target serial femtosecond crystallography (FT-SFX) was an important advance in crystallography by dramatically reducing sample consumption, while maintaining the benefits of SFX for obtaining crystal structures at room temperature without radiation damage. Despite a number of advantages, preparation of a sample holder for the sample delivery in FT-SFX with the use of many crystals in a single mount at ambient temperature is challenging as it can be complicated and costly, and thus, development of an efficient sample holder is essential. In this study, we introduced a nylon mesh-based sample holder enclosed by a polyimide film. This sample holder can be rapidly manufactured using a commercially available nylon mesh with pores of a desired size at a low cost without challenging technology. Furthermore, this simple device is highly efficient in data acquisition. We performed FT-SFX using a nylon mesh-based sample holder and collected over 130,000 images on a single sample holder using a 30 Hz X-ray pulse for 1.2 h. We determined the crystal structures of lysozyme and glucose isomerase using the nylon mesh at 1.65 and 1.75 Å, respectively. The nylon mesh exposed to X-rays produced very low levels of background scattering at 3.75 and 4.30 Å, which are negligible for data analysis. Our method provides a simple and rapid but highly efficient way to deliver samples for FT-SFX.

We investigated the relationship between grain boundary (GB) oxidation of Cu−Ag thin-film catalysts and selectivity of the (photo)electrochemical CO 2 reduction reaction (CO 2 RR). The change in the thickness of the Cu thin film accompanies the variation of GB density, and the Ag layer (3 nm) has an island-like morphology on the Cu thin film. Therefore, oxygen from ambient air penetrates into the Cu thin film through the GB of Cu and binds with it because the uncoordinated Cu atoms at the GBs are unstable. It was found that the Cu thin film with a small grain size was susceptible to spontaneous oxidation and degraded the faradaic efficiency (FE) of CO and CH 4 . However, a relatively thick (≥80 nm) Cu layer was effective in preventing the GB oxidation and realized catalytic properties similar to those of bulk Cu−Ag catalysts. The optimized Cu (100 nm)−Ag (3 nm) thin film exhibited a unique bifunctional characteristic, which enables selective production of both CO (FE CO = 79.8%) and CH 4 (FE CH4 = 59.3%) at a reductive potential of −1.0 and −1.4 V RHE , respectively. Moreover, the Cu−Ag thin film was used as a cocatalyst for photo-electrochemical CO 2 reduction by patterning the Cu−Ag thin film and a SiO 2 passivation layer on a p-type Si photocathode. This novel architecture improved the selectivity of CO and CH 4 under light illumination (100 mW/cm 2 ).

Microcrystal delivery methods are pivotal in the use of serial femtosecond crystallography (SFX) to resolve the macromolecular structures of proteins. Here, the development of a novel technique and instruments for efficiently delivering microcrystals for SFX are presented. The new method, which relies on a one‐dimensional fixed‐target system that includes a microcrystal container, consumes an extremely low amount of sample compared with conventional two‐dimensional fixed‐target techniques at ambient temperature. This novel system can deliver soluble microcrystals without highly viscous carrier media and, moreover, can be used as a microcrystal growth device for SFX. Diffraction data collection utilizing this advanced technique along with a real‐time visual servo scan system has been successfully demonstrated for the structure determination of proteinase K microcrystals at 1.85 Å resolution.

The electrochemical carbon dioxide (CO 2 ) reduction is a promising method for carbon recycling. Bimetallic catalysts have been extensively developed for the selective production of carbon monoxide (CO) and formate (HCOOH), while efforts to understand the change in structure and composition under reaction conditions have been limited. Here, we provided experimental evidence for the local corrosion phenomenon of bimetallic Cu−Sn catalysts through the patterning of the Sn layer on Cu foil (Cu/p-Sn). The surface composition and morphology of Cu/p-Sn 3 nm catalysts spontaneously changed during the reaction in CO 2 -purged 0.1 M KHCO 3 electrolyte. The Sn patterns became thinner, and the Sn elements were migrated to the outside of the patterns. Consequently, the Cu/p-Sn catalysts exhibited a unique catalytic selectivity of high CO faradaic efficiency (FE CO ) of 58.1% at −1.0 V RHE , which cannot be obtained from the bulk Cu (FE CO = 7.5%) and Cu/Sn catalysts without the Sn pattern (FE HCOOH = 90.6%). Moreover, the catalytic selectivity of the Cu/p-Sn catalysts shifted from CO to HCOOH as the thickness of the Sn pattern increased from 3 to 50 nm. This study sheds light on the origin of the local corrosion of bimetallic catalysts and its effect on the catalytic selectivity of CO 2 reduction.