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The continuously growing importance of information storage, transmission, and authentication impose many new demands and challenges for modern nano-photonic materials and information storage technologies, both in security and storage capacity. Recently, luminescent lanthanide-doped nanomaterials have drawn much attention in this field because of their photostability, multimodal/multicolor/narrowband emissions, and long luminescence lifetime. Here, we report a multimodal nanocomposite composed of lanthanide-doped upconverting nanoparticle and EuSe semiconductor, which was constructed by utilizing a cation exchange strategy. The nanocomposite can emit blue and white light under 365 and 394 nm excitation, respectively. Meanwhile, the nanocomposites show different colors under 980 nm laser excitation when the content of Tb3+ ions is changed in the upconversion nanoparticles. Moreover, the time-gating technology is used to filter the upconversion emission of a long lifetime from Tb3+ or Eu3+, and the possibilities for modulating the emission color of the nanocomposites are further expanded. Based on the advantage of multiple tunable luminescence, the nanocomposites are designed as optical modules to load optical information. This work enables multi-dimensional storage of information and provides new insights into the design and fabrication of next-generation storage materials.

Modulating the emission wavelengths of materials has always been a primary focus of fluorescence technology. Nanocrystals (NCs) doped with lanthanide ions with rich energy levels can produce a variety of emissions at different excitation wavelengths. However, the control of multimodal emissions of these ions has remained a challenge. Herein, we present a new composition of Er3+‐based lanthanide NCs with color‐switchable output under irradiation with 980, 808, or 1535 nm light for information security. The variation of excitation wavelengths changes the intensity ratio of visible (Vis)/near‐infrared (NIR‐II) emissions. Taking advantage of the Vis/NIR‐II multimodal emissions of NCs and deep learning, we successfully demonstrated the storage and decoding of visible light information in pork tissue.

Here, the effect of morphology on the electrocatalytic activity of metal–organic framework (MOF) was investigated. Post synthetic gold (Au) insertion was done into hollow PCN-222 (HPCN-222) and solid PCN-222 (SPCN-222) frameworks by a simple hydrothermal method. The crystalline nature, chemical composition, and morphologies of the synthesized MOFs were characterized by PXRD, XPS, and TEM. Electrochemical characterizations were done by cyclic voltammetry and electrochemical impedance spectroscopy. The excellent electrocatalytic activity of highly small-sized Au(0) with the enhancement of electrical conductivity through a hopping mechanism combined with a hollow structure and high surface area in the HPCN-222 MOF hugely alters the electrochemical properties. Overall, a better electrocatalytic surface area, charge transfer coefficient, and catalytic activity were generated at the modified electrode. The hollow structure MOF showed better electrocatalytic activity than solid structured MOF. The AuHPCN-222 modified glassy carbon electrode (AuHPCN-222/GCE) electrochemical sensor was employed for the analytical analysis of estradiol (ED) in an optimum experimental condition. AuHPCN-222 showed selective and better electrocatalytic activity toward ED than GCE. The differential pulse voltammetric measurements by the fabricated sensor showed two linear determination ranges for ED; those are 0.01–1 and 1–220 μM. The measured limit of detection (m-LOD) was found to be 0.5 nM with the highest sensitivity of 2.2 μA μM cm–2. The analytical performances for the detection of ED in human urine and serum samples were done with reasonable recoveries (98%–103%) using the standard addition method. Also, the sensor showed better reproducibility and repeatability with stability.

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In this work, a nanocomposite of Zr-trimesic acid MOF (MOF-808) with carbon nanotube (CNT) was synthesized through an in situ formation of MOF-808 on the activated CNT. The synthesized materials were characterized by powder X-ray diffraction, transmission electron microscopy, X-ray photoluminescence spectroscopy, Brunauer–Emmett–Teller, Fourier transform infrared spectroscopy, and Raman spectroscopy. The protein compatible nature with high surface area and electrocatalytic ability of MOF-808 was utilized to construct an immunosensor for ultra low-level detection of the ovarian cancer biomarker, carbohydrate antigen 125 (CA 125). The mutual benefit of each constituent of the MOF-808/CNT composite was capable of producing highly enhanced electrochemical properties. A glassy carbon electrode modified with MOF-808/CNT was used as a platform to fabricate a label-free electrochemical immunosensor. The antibody binding sites of MOF-808/CNT were enriched by functionalization with streptavidin. The immunosensor exhibited two linear determination ranges of 0.001–0.1 and 0.1–30 ng·mL–1, and the calculated limit of detection was 0.5 pg·mL–1 (S/N 3). The immunosensor showed excellent reproducibility and selectivity. The patient serum sample analysis was cross-verified with the electrochemiluminescence method with a relative error of 105–110%.

Electrochemical storage via conversion reactions in crystalline electrode materials critically rests upon the sizes of the guest ions. Here we report an unusual behavior that renders CuO inactive in the process of sodium-ion insertion with a synergistic combination of a variety of synchrotron X-ray microscopic, spectroscopic, and structural probes. We reveal that the "unreactive core" formation is closely associated with the microstructural integrity of battery active materials. In light of these findings, we also demonstrate that this undesirable process can be inhibited by the materials' microstructural design to trigger the potential of high electrochemical properties.