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A deep understanding of how the host matrix influences the afterglow properties of molecule dopants is crucial for designing advanced afterglow materials. Despite its appeal, the impact of defects on the afterglow performance in molecule-doped SiO2 matrices has remained largely unexplored. Herein, we detail the synthesis of monodisperse SiO2 microparticles by hydrothermally doping molecules, such as 4-phenylpyridine, 4,4'-bipyridine, and 1,4-bis(pyrid-4-yl)benzene. Our results demonstrate that hydrothermal reactions induce not only the formation of emissive defects in the SiO2 matrix but also enable molecule doping through SiO2 pseudomorphic transformation. Optical analyses reveal a remarkable afterglow activation of doped molecules, driven by a synergistic interplay of hydrogen bonding and physical fixation. Specifically, 4-phenylpyridine doping leads to an impressive 227- and 271-fold enhancement in fluorescence and afterglow, respectively, and an extraordinary 3711-fold enhancement in the afterglow lifetime of the resulting SiO2 MPs. We also document hybrid states involving molecule dopants and SiO2 defects, explaining energy transfer from molecule dopants to defects in both singlet and triplet states. The robust achievement of molecule doping provides flexibility to tailor excitation-dependent afterglow attributes while preserving angle-dependent structural colors, facilitating the creation of diverse building blocks for multiscale optical platforms for afterglow modulation and information encoding. Silica encapsulation can quench nonradiative relaxation and yield afterglow emission in materials. Here, the authors transfer this strategy to molecular emitters by doping them into silica microparticles enhancing both emission intensity and lifetimes. [ABSTRACT FROM AUTHOR]

A deep understanding of how the host matrix influences the afterglow properties of molecule dopants is crucial for designing advanced afterglow materials. Despite its appeal, the impact of defects on the afterglow performance in molecule-doped SiO2 matrices has remained largely unexplored. Herein, we detail the synthesis of monodisperse SiO2 microparticles by hydrothermally doping molecules, such as 4-phenylpyridine, 4,4'-bipyridine, and 1,4-bis(pyrid-4-yl)benzene. Our results demonstrate that hydrothermal reactions induce not only the formation of emissive defects in the SiO2 matrix but also enable molecule doping through SiO2 pseudomorphic transformation. Optical analyses reveal a remarkable afterglow activation of doped molecules, driven by a synergistic interplay of hydrogen bonding and physical fixation. Specifically, 4-phenylpyridine doping leads to an impressive 227- and 271-fold enhancement in fluorescence and afterglow, respectively, and an extraordinary 3711-fold enhancement in the afterglow lifetime of the resulting SiO2 MPs. We also document hybrid states involving molecule dopants and SiO2 defects, explaining energy transfer from molecule dopants to defects in both singlet and triplet states. The robust achievement of molecule doping provides flexibility to tailor excitation-dependent afterglow attributes while preserving angle-dependent structural colors, facilitating the creation of diverse building blocks for multiscale optical platforms for afterglow modulation and information encoding. Silica encapsulation can quench nonradiative relaxation and yield afterglow emission in materials. Here, the authors transfer this strategy to molecular emitters by doping them into silica microparticles enhancing both emission intensity and lifetimes. [ABSTRACT FROM AUTHOR]

Lead-free alkali halides have gained increasing attention owing to their desired optoelectronic properties across a variety of light-emitting applications. However, state-of-the-art alkali halide emitters commonly are bulky crystals functionalized with highly toxic elemental doping, hindering their integration into emerging flexible, wearable and large-area optoelectronic devices. Herein, we have developed environmental friendly and solution-processable alkali halide nanocrystals that exhibit intense self-trapped emission facilitated by Sn2+ ionic doping. We find that the presence of Sn2+-interstitial leads to the tilting of cubic structures of RbI and thus triggers the self-trapped emission. The resultant tin(II)-doped RbI and RbxCs1−xI nanocrystals display an impressive maximum photoluminescence quantum yield of 91.9% and exhibit remarkable stability under ambient conditions. These findings pave the way for a new class of bright, solution-processable alkali halides, with diverse applications such as energy down conversion and flexible scintillation technologies. [ABSTRACT FROM AUTHOR]

Copper halides, a new class of attractive and potential scintillators, have attracted tremendous attention in X‐ray imaging. However, the ambiguity surrounding their exciton properties and the unclear effect of crystal structure on their photophysical performance hinder an in‐depth understanding of their luminescence mechanism and their further application in the X‐ray imaging field. Herein, copper halide scintillators Cs3Cu2X5 (X = I, Br, and Cl) with a 0D crystal structure is prepared, and their photophysical properties and luminescence mechanism are revealed using both theoretical calculation and experimental verification. The small exciton Bohr diameter together with the high exciton binding energy can cause Cs3Cu2X5 to hold strongly confined excitons and lack quantum‐size effects. The 0D Cs3Cu2X5 materials exhibit a structural framework with a soft crystal lattice and Frenkel excitons with strong confinement effects, further resulting in a luminescence mechanism with self‐trapped excitons. In particular, Cs3Cu2I5 is demonstrated as an efficient scintillator with high radioluminescence efficiency and high spatial resolution of ≈106 µm in radiography, which is primarily attributed to strongly confined excitons to improve the radiative recombination probability of electron‐hole pairs. Overall, this work provides a pathway for developing 0D scintillators with strongly confined excitons to improve X‐ray imaging performance. [ABSTRACT FROM AUTHOR]

The thickness of the scintillation films in indirect X−ray detectors can significantly influence their luminescence intensity. However, due to the scattering and attenuation of incoherent photons, thick scintillation films tend to reduce light yield. Herein, a highly transparent perovskite glass−ceramic scintillation film, in which the CsPbBr3 nanocrystals are in-situ grown inside a transparent amorphous polymer structure, is designed to achieve ultrastable and efficient X-ray imaging. The crystal coordination−topology growth and in−situ film formation strategy is proposed to control the crystal growth and film thickness, which can prevent light scattering and non−uniform distribution of CsPbBr3 nanocrystals while providing sufficient film thickness to absorb X−ray, thus enabling a high−quality glass−ceramic scintillator without agglomeration and Ostwald ripening. This glass−ceramic scintillation film with a thickness of 250 μm achieves a low detection limit of 326 nGyair s−1 and a high spatial resolution of 13.9 lp mm−1. More importantly, it displays remarkable scintillation stability under X−ray irradiation (radiation intensity can still reach 95% at 278 μGyair s−1 for 3600 s), water soaking (150 days), and high−temperature storage (150 days at 60 °C). Hence, this work presents a approach to construct ultrastable and flexible scintillation films for X−ray imaging with reduced light scattering and improved resolution. [ABSTRACT FROM AUTHOR]

Supramolecular multifunctional metal–organic networks offer immense potential in drug delivery, bioimaging, catalysis, and therapeutics. However, the creation of multiple stimuli‐responsive fluorescent hollow nano/microparticles is a formidable challenge in this field. In this study, a novel strategy is reported for synthesizing photochromic hollow microparticles that exhibit responsiveness to light, pH, and glutathione (GSH). With the assistance of templating coordination from zeolitic imidazolate framework‐8 microparticles, bisphosphonate‐merocyanine ligands are successfully assembled to create hollow bisphosphonate‐spiropyran (BPSP)‐Zn2+ microparticles. The photochromic and pH responses stem from the reversible conversion between spiropyran and zwitterionic merocyanine components and between merocyanine and protonated merocyanine, respectively. The GSH response is attributed to the stronger affinity of Zn2+ to thiol groups than to phosphonate groups. These remarkable features render the hollow BPSP‐Zn2+ microparticles highly suitable for applications in stimulus‐triggered drug delivery, and these findings provide a platform for developing innovative materials that have the potential to transform the biomedical field. [ABSTRACT FROM AUTHOR]

In the era of intelligence, the output colors of foundational phosphors are expected to be controlled by programs, while current activators‐determined afterglow candidates with fixed spectral channel have limitations in creating customized colors. Here, a long‐lived warm‐white emission is successfully demonstrated originating from self‐trapped excitons (STEs) in non‐toxic Cs2NaInCl6:Ag,Bi, ranging from 400 to 850 nm, of which the afterglow color can be easily customized using filters. This investigation indicates that 3% of Ag alloying breaks the dark STEs and introduces traps for efficient afterglow, while 3% Bi doping further improves the quantum yield to ≈100% and greatly enhances afterglow by ≈100‐fold compared with the initial intensity, allowing for an impressive afterglow persistence of over 20,000 s. Intriguingly, the self‐trapped defect bands from Jahn‐Teller distortions are prolonged from hundreds of femtoseconds to several hours, and they are first detected in the steady‐state absorption spectra after the cessation of excitation sources, contributing to the concluded dynamic afterglow model for STEs. And its intelligent application is corroborated by designed multi‐channel information system. These findings offer a novel scheme for understanding dynamic luminescence of STEs and supply an exemplification of designing white afterglow phosphors. [ABSTRACT FROM AUTHOR]

With the increasing demands of X‐ray detection and medical diagnosis, organic scintillators with intense and tunable X‐ray excited emission have been becoming important. To guarantee the X‐ray absorption, heavy atoms were widely added in reported organic scintillators, which led to emission quenching. In this work, we propose a new strategy to realize organic scintillators through the host‐guest doping strategy. Then the X‐ray absorption centers (host) and emission centers (guest) are separated. Under X‐ray excitation, these materials displayed intense and readily tunable emissions ranging from green (520 nm) to near infrared (NIR) regions (682 nm). Besides, the relationship between the X‐ray absorption and spatial arrangement of the heavy atoms in the host matrix was also revealed. The potential application of these wide‐range color tunable organic host‐guest scintillators in X‐ray imaging were demonstrated. This work provides a new feasible strategy for constructing high‐performance organic scintillators with tunable luminescence properties. [ABSTRACT FROM AUTHOR]

With the increasing demands of X‐ray detection and medical diagnosis, organic scintillators with intense and tunable X‐ray excited emission have been becoming important. To guarantee the X‐ray absorption, heavy atoms were widely added in reported organic scintillators, which led to emission quenching. In this work, we propose a new strategy to realize organic scintillators through the host‐guest doping strategy. Then the X‐ray absorption centers (host) and emission centers (guest) are separated. Under X‐ray excitation, these materials displayed intense and readily tunable emissions ranging from green (520 nm) to near infrared (NIR) regions (682 nm). Besides, the relationship between the X‐ray absorption and spatial arrangement of the heavy atoms in the host matrix was also revealed. The potential application of these wide‐range color tunable organic host‐guest scintillators in X‐ray imaging were demonstrated. This work provides a new feasible strategy for constructing high‐performance organic scintillators with tunable luminescence properties. [ABSTRACT FROM AUTHOR]

The ability to tune afterglow attributes of organic materials can largely extend their utility in the field of lifetime‐encoded security applications. Herein, the tuning of afterglow intensity and lifetime of molecule emitters after being doped into copolymer by photoinitiated solvent‐free copolymerization are reported. The molar ratio adjustment of 2‐hydroxyethyl acrylate and 2‐hydroxyethyl methacrylate in copolymerization allows systematic tuning of the rigidity of the resultant copolymers by occupying the free volume through methyl groups, enabling controlled stabilization of the in situ generated triplet excitons of the doped molecule emitters via effectively decreasing vibrational energy dissipation. With the use of this strategy, the green afterglow for 2,3‐naphthalenedicarboxylic anhydride can be tuned with a lifetime from 170.1 to 1258.6 ms, accompanied by a 76‐fold intensity enhancement. Furthermore, this strategy can be extended to tune multicolor afterglow materials through the choice of molecule dopants. When combined with digital light processing printing, the strategy allows for the facile fabrication of lifetime‐encoded complex 3D objects with high precisions for security applications. [ABSTRACT FROM AUTHOR]

The search for color‐tunable, efficient, and robust scintillators plays a vital role in the development of modern X‐ray radiography. The radioluminescence tuning of copper iodide cluster scintillators in the entire visible region by bandgap engineering is herein reported. The bandgap engineering benefits from the fact that the conduction band minimum and valence band maximum of copper iodide cluster crystals are contributed by atomic orbitals from the inorganic core and organic ligand components, respectively. In addition to high scintillation performance, the as‐prepared crystalline copper iodide cluster solids exhibit remarkable resistance toward both moisture and X‐ray irradiation. These features allow copper iodide cluster scintillators to show particular attractiveness for low‐dose X‐ray radiography with a detection limit of 55 nGy s−1, a value ≈100 times lower than a standard dosage for X‐ray examinations. The results suggest that optimizing both inorganic core and organic ligand for the building blocks of metal halide cluster crystals may provide new opportunities for a new generation of high‐performance scintillation materials. [ABSTRACT FROM AUTHOR]

Mitochondria are inextricably linked to the development of diseases and cell metabolism disorders. Super-resolution imaging (SRI) is crucial in enhancing our understanding of mitochondrial ultrafine structures and functions. In addition to high-precision instruments, super-resolution microscopy relies heavily on fluorescent materials with unique photophysical properties. Small-molecule fluorogenic probes (SMFPs) have excellent properties that make them ideal for mitochondrial SRI. This paper summarizes recent advances in the field of SMFPs, with a focus on the chemical and spectroscopic properties required for mitochondrial SRI. Finally, we discuss future challenges in this field, including the design principles of SMFPs and nanoscopic techniques. [ABSTRACT FROM AUTHOR]

Mn2+ dopants introduce a new emission center in semiconductor luminescent materials, endowing them promising photoluminescence (PL) properties, such as a wide color tuning range, reversible color change, reduced self‐absorption etc. Recently, rapid development of Mn2+ doped metal halide perovskites (MHPs) promote their promising applications in displays, photovoltaics, scintillators, etc. The emission color, luminous efficiency, and energy transfer pathway of doped perovskites are affected by condition of host lattice that accommodates Mn2+ ions. In this review, the optical properties determined by host materials with diverse geometries involving perovskite nanocrystals and perovskite derivatives is focused on, and the possible energy transfer routes in different doping systems are analyzed. An overview of recent advances of different doped systems with assigned emission channels together with the influence factors, strategies to enhance PL intensity and finally potential applications are summarized. To the end, the underlying challenges and possible solutions for further research in Mn doped perovskites are proposed. [ABSTRACT FROM AUTHOR]

Nanoscintillators (nanocrystals with X‐ray scintillation performance) lay a fundamental for their practical application in high‐resolution and low‐dose medical examination due to their excellent photoelectric properties. The optical properties and scintillation performance of nanocrystals (NCs) can be significantly affected by adjusting their size. However, the mechanism of the size effect of NCs on optical properties and X‐ray scintillation performance has not been revealed. Here, a mathematical model and experimental results are combined to demonstrate the impact of the size of NCs on their scintillation performance. The results show that the surface area and volume of NCs exhibit a positive and negative impact on the change rate of the bandgap, respectively. This model further verifies that the photoluminescence quantum yield of NCs decreases with the decrease of their size, and their light yield is remarkably affected by the size of NCs. Overall, this work provides some enlightenment for researchers to design NCs with the appropriate size for their applications in high‐performance X‐ray scintillation. [ABSTRACT FROM AUTHOR]

The ability to tune photochromic features of nanoparticle (NP)‐ligand conjugates can vastly extend the utility of dynamic materials in the fields of drug delivery, bioimaging, and data storage. Herein, the photochromic tuning of lanthanide‐doped upconversion nanoparticle (UCNP)‐spiropyran (SP) conjugates through a binary ligand strategy is reported. It is found that the content of SP ligand on the surface of UCNPs can be rationally controlled by an SP‐to‐oleate ligand exchange reaction, allowing for regulating the steric congestion in the ligand layer. A highly congested SP layer not only leads to an ultralong lifetime for the purple open‐ring state but also results in improved red fluorescence under UV excitation. The enhancement in steric congestion further enables increased activation energy for the ring‐opening reaction for the bound SP ligand, permitting the generation of high‐resolution self‐erasing patterns in a UCNP‐SP conjugate‐doped polydimethylsiloxane film by local irradiation with either UV or near‐infrared light. The findings provide new insights into the optical tuning of nanoconjugates by controlling the conformational dynamics of their mixed ligand layers. [ABSTRACT FROM AUTHOR]

Scintillators that exhibit X-ray-excited luminescence have great potential in radiation detection, X-ray imaging, radiotherapy, and non-destructive testing. However, most reported scintillators are limited to inorganic or organic crystal materials, which have some obstacles in repeatability and processability. Here we present a facile strategy to achieve the X-ray-excited organic phosphorescent scintillation from amorphous copolymers through the copolymerization of the bromine-substituted chromophores and acrylic acid. These polymeric scintillators exhibit efficient X-ray responsibility and decent phosphorescent quantum yield up to 51.4% under ambient conditions. The universality of the design principle was further confirmed by a series of copolymers with multi-color radioluminescence ranging from green to orange-red. Moreover, we demonstrated their potential application in X-ray radiography. This finding not only outlines a feasible principle to develop X-ray responsive phosphorescent polymers, but also expands the potential applications of polymer materials with phosphorescence features. The authors achieved the X-ray-excited organic phosphorescent scintillation from copolymers through copolymerization of bromine-substituted chromophores and acrylic acid and demonstrated their potential application in X-ray radiography. [ABSTRACT FROM AUTHOR]

Due to the merits of decreased photon attenuation, autofluorescence, and scattering, the near‐infrared (NIR, 700–1700 nm) region is an important window in the field of biomedicine, such as in vivo fluorescence imaging, in which both the optical detection depth and the resolution/contrast have been significantly improved. In particular, for second NIR (NIR‐II, 1000–1700 nm) dyes, biological tissues have almost no background interference. Typical fluorophores have excellent spectral performance and rich functional modification sites and can be optimized into NIR dyes for bioimaging. However, as the absorption/emission wavelength of fluorophores redshift to NIR, it is challenging to keep fluorophores with satisfying brightness. Therefore, for the purpose of increasing the absorption/emission wavelength of dye while promoting its brightness, it is necessary to study the structure–property relationship of the dyes. This review introduces the influences of fluorophores' structure on their photophysical properties, summarizes the strategies for maintaining high fluorescence brightness along with redshifted absorption/emission wavelengths, and the latest advances of highly fluorescent brightness dyes. Finally, the opportunities and challenges in this emerging field are also provided. The authors aim to provide insightful design guidelines and clear overview of highly bright NIR fluorescent dyes, which might trigger new ideas and applications. [ABSTRACT FROM AUTHOR]

D‐amino acids (DAAs) are indispensable in regulating diverse metabolic pathways. Selective and sensitive detection of DAAs is crucial for understanding the complexity of metabolic processes and managing associated diseases. However, current DAA detection strategies mainly rely on bulky instrumentation or electrochemical probes, limiting their cellular and animal applications. Here we report an enzyme‐coupled nanoprobe that can detect enantiospecific DAAs through synergistic energy transfer. This nanoprobe offers near‐infrared upconversion capability, a wide dynamic detection range, and a detection limit of 2.2 μM, providing a versatile platform for in vivo noninvasive detection of DAAs with high enantioselectivity. These results potentially allow real‐time monitoring of biomolecular handedness in living animals, as well as developing antipsychotic treatment strategies. [ABSTRACT FROM AUTHOR]

D‐amino acids (DAAs) are indispensable in regulating diverse metabolic pathways. Selective and sensitive detection of DAAs is crucial for understanding the complexity of metabolic processes and managing associated diseases. However, current DAA detection strategies mainly rely on bulky instrumentation or electrochemical probes, limiting their cellular and animal applications. Here we report an enzyme‐coupled nanoprobe that can detect enantiospecific DAAs through synergistic energy transfer. This nanoprobe offers near‐infrared upconversion capability, a wide dynamic detection range, and a detection limit of 2.2 μM, providing a versatile platform for in vivo noninvasive detection of DAAs with high enantioselectivity. These results potentially allow real‐time monitoring of biomolecular handedness in living animals, as well as developing antipsychotic treatment strategies. [ABSTRACT FROM AUTHOR]

The self-assembly of colloidal nanoparticles has made it possible to bridge the nanoscopic and macroscopic worlds and to make complex nanostructures. The nanoparticle-mediated assembly enables many potential applications, from biodetection and nanomedicine to optoelectronic devices. Properties of assembled materials are determined not only by the nature of nanoparticle building blocks, but also by spatial positions of nanoparticles within the assemblies. A deep understanding of nanoscale interactions between nanoparticles is a prerequisite to controlling nanoparticle arrangement during assembly. In this review, we present an overview of interparticle interactions governing their assembly in a liquid phase. Considerable attention is devoted to examples that illustrate nanoparticle assembly into ordered superstructures using different types of building blocks, including plasmonic nanoparticles, magnetic nanoparticles, lanthanide-doped nanophosphors, and quantum dots. We also cover the physicochemical properties of nanoparticle ensembles, especially those arising from particle coupling effects. We further discuss future research directions and challenges in controlling self-assembly at a level of precision that is most crucial to technology development. [ABSTRACT FROM AUTHOR]

The ability to incorporate functional metal ions (Mn+) into metal–organic coordination complexes adds remarkable flexibility in the synthesis of multifunctional organic–inorganic hybrid materials with tailorable electronic, optical, and magnetic properties. We report the cation‐exchanged synthesis of a diverse range of hollow Mn+‐phytate (PA) micropolyhedra via the use of hollow Co2+‐PA polyhedral networks as templates at room temperature. The attributes of the incoming Mn+, namely Lewis acidity and ionic radius, control the exchange of the parent Co2+ ions and the degree of morphological deformation of the resulting hollow micropolyhedra. New functions can be obtained for both completely and partially exchanged products, as supported by the observation of Ln3+ (Ln3+=Tb3+, Eu3+, and Sm3+) luminescence from as‐prepared hollow Ln3+‐PA micropolyhedra after surface modification with dipicolinic acid as an antenna. Moreover, Fe3+‐ and Mn2+‐PA polyhedral complexes were employed as magnetic contrast agents. [ABSTRACT FROM AUTHOR]

The ability to incorporate functional metal ions (Mn+) into metal–organic coordination complexes adds remarkable flexibility in the synthesis of multifunctional organic–inorganic hybrid materials with tailorable electronic, optical, and magnetic properties. We report the cation‐exchanged synthesis of a diverse range of hollow Mn+‐phytate (PA) micropolyhedra via the use of hollow Co2+‐PA polyhedral networks as templates at room temperature. The attributes of the incoming Mn+, namely Lewis acidity and ionic radius, control the exchange of the parent Co2+ ions and the degree of morphological deformation of the resulting hollow micropolyhedra. New functions can be obtained for both completely and partially exchanged products, as supported by the observation of Ln3+ (Ln3+=Tb3+, Eu3+, and Sm3+) luminescence from as‐prepared hollow Ln3+‐PA micropolyhedra after surface modification with dipicolinic acid as an antenna. Moreover, Fe3+‐ and Mn2+‐PA polyhedral complexes were employed as magnetic contrast agents. [ABSTRACT FROM AUTHOR]

The development of an ultrastable and efficient technology for H2 production is an important step in the utilization of renewable and clean energy. Herein, we report that hybrid water electrolysis, integrating the electrochemical reforming of benzyl alcohol (BA) and the H2 evolution reaction (HER), largely accelerates the kinetics and stability of H2 production over a hierarchical bifunctional catalyst couple of Mo–Ni alloy nanoparticles in 1.0 M KOH. The high-performance of the hierarchical Mo–Ni nanoparticle catalyst for both the HER and the BA oxidation not only eliminated the need for an ion-conducting membrane to separate the cathodic and anodic reactions to achieve nearly unity faradaic efficiences for the two reactions, but also allowed the reactions to be readily driven by low cell voltage in a two-electrode configuration. Specifically, the cell voltages required to deliver the benchmark current densities of 20, 50, and 100 mA cm−2 are as low as 1.40, 1.45, and 1.53 V, respectively. The membrane-free hybrid water electrolysis technology exhibits a set of advantages including long device lifetime, ease of H2 collection, and high efficiency, thus showing significant promise for practical H2 production, especially considering the fact that the device can be readily powered by a single-cell alkaline battery or a solar cell under natural sunlight irradiation. [ABSTRACT FROM AUTHOR]

Abstract: The practical use of overall water electrolysis is largely hindered by the need for precious noble metal‐based catalysts. Here, the colloidal synthesis of earth‐abundant electrocatalysts of Mo–Ni nanoparticles for efficient water splitting by thermal decomposition of Ni(acac)2 and Mo(CO)6 in the presence of 1‐octadecene and oleylamine at 320 °C is reported. It is shown that the optimized catalysts (Mo0.6Ni0.4) only require low overpotentials of 0.065 V for the hydrogen evolution reaction (HER) and of 290 mV for the oxygen evolution reaction (OER) to deliver a current density of 10 mA cm−2 in KOH (1.0 m). The as‐prepared Mo–Ni alloy nanoparticles also show extraordinary durability for both the HER and OER. A low potential of ≈1.62 V is required to yield a current density of 10 mA cm−2 when utilizing the alloy nanoparticles as bifunctional catalysts in a two‐electrode electrolyzer system. The ease of preparing either rigid or flexible high‐performance electrodes by making use of the alloy nanoparticle electrocatalysts without the need for binder further suggests the attractive application of colloidally stable nanoparticles in the field of electrochemical water splitting. [ABSTRACT FROM AUTHOR]

The efficient and selective palladium-catalyzed activation of C−H bonds is of great importance for the construction of diverse bioactive molecules. Despite significant progress, the inability to recycle palladium catalysts and the need for additives impedes the practical applications of these reactions. Ag1Pd1 nanoparticles-reduced graphene oxide (Ag1Pd1-rGO) was used as highly efficient and recyclable catalyst for the chelation-assisted ortho C−H bond olefination of amides with acrylates in good yields with a broad substrate scope. The catalyst can be recovered and reused at least 5 times without losing activity. A synergistic effect between the Ag and Pd atoms on the catalytic activity was found, and a plausible mechanism for the AgPd-rGO catalyzed C−H olefination is proposed. These findings suggest that the search for such Pd-based bimetallic alloy nanoparticles is a new method towards the development of superior recyclable catalysts for direct aryl C−H functionalization under mild conditions. [ABSTRACT FROM AUTHOR]

Surface-nitrogen enriched carbon spheres with core-shell structure were prepared by a facile and general strategy with dopamine and melamine as the precursors. This strategy includes three steps: the polymerization of dopamine to form polydopamine (PDA) spheres, the soaking of spheres in melamine (MA) and the pyrolysis of PDA spheres/MA. The resulting carbon spheres as electrode materials for supercapacitors display better performances than common N-doped carbon spheres (NCS) with a high specific capacitance (203 F/g at 0.5 A/g), acceptable rate capability (66% retention at 5 A/g) and good long-term stability (94.6% retention after 5000 cycles at 2 A/g). This formation of polymer spheres-soaking in inflating agent-pyrolysis strategy makes it easy to produce surface-nitrogen-rich and hierarchically porous carbon spheres on a large scale with different sources. These carbon spheres hold great potential applications in energy storage and conversion devices such as supercapacitors and fuel cells due to their unique structure and hierarchical composition. [ABSTRACT FROM AUTHOR]

Herein, we present a simple and facile synthesis strategy of porous N-doped graphene (N-Gr) using a facile one-step pyrolysis method. The as-prepared N-Gr was characterized by power X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. N-Gr-modified glassy carbon electrode exhibited a lower overpotential and the higher redox peak currents for catechin during the electrochemical reaction of catechin. At the N-Gr-modified electrode, the redox process of catechin was almost reversible and displayed an adsorption-controlled redox process with a fast electron transfer rate. The linear responses of the sensor for catechin have been obtained by the differential pulse voltammetry in the range from 1.0 to 30 μM with the calculated detection limit of 0.088 μM ( S/ N = 3). The real application of catechin in Chinese green tea samples with excellent performance such as long-term stability and good reproducibility was successfully achieved. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of cubic NaGdF4:Yb/Tm@NaGdF4:Mn core-shell structures. By taking advantage of energy transfer through Yb→Tm→Gd→Mn in these core-shell nanoparticles, we have realized upconversion emission of Mn2+ at room temperature in lanthanide tetrafluoride based host lattices. The upconverted Mn2+emission, enabled by trapping the excitation energy through a Gd3+ lattice, was validated by the observation of a decreased lifetime from 941 to 532 μs in the emission of Gd3+ at 310 nm (6P7/2→8S7/2). This multiphoton upconversion process can be further enhanced under pulsed laser excitation at high power densities. Both experimental and theoretical studies provide evidence for Mn2+ doping in the lanthanide-based host lattice arising from the formation of F− vacancies around Mn2+ ions to maintain charge neutrality in the shell layer. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of cubic NaGdF4:Yb/Tm@NaGdF4:Mn core-shell structures. By taking advantage of energy transfer through Yb→Tm→Gd→Mn in these core-shell nanoparticles, we have realized upconversion emission of Mn2+ at room temperature in lanthanide tetrafluoride based host lattices. The upconverted Mn2+emission, enabled by trapping the excitation energy through a Gd3+ lattice, was validated by the observation of a decreased lifetime from 941 to 532 μs in the emission of Gd3+ at 310 nm (6P7/2→8S7/2). This multiphoton upconversion process can be further enhanced under pulsed laser excitation at high power densities. Both experimental and theoretical studies provide evidence for Mn2+ doping in the lanthanide-based host lattice arising from the formation of F− vacancies around Mn2+ ions to maintain charge neutrality in the shell layer. [ABSTRACT FROM AUTHOR]

Probing the nature of nanocrystalline materials such as the surface state, crystal structure, morphology, composition, optical and magnetic characteristics is a crucial step in understanding their chemical and physical performance and in exploring their potential applications. Upconversion nanocrystals have recently attracted remarkable interest due to their unique nonlinear optical properties capable of converting incident near-infrared photons to visible and even ultraviolet emissions. These optical nanomaterials also hold great promise for a broad range of applications spanning from biolabeling to optoelectronic devices. In this review, we overview the instrumentation techniques commonly utilized for the characterization of upconversion nanocrystals. A considerable emphasis is placed on the analytical tools for probing the optical properties of the luminescent nanocrystals. The advantages and limitations of each analytical technique are compared in an effort to provide a general guideline, allowing optimal conditions to be employed for the characterization of such nanocrystals. Parallel efforts are devoted to new strategies that utilize a combination of advanced emerging tools to characterize such nanosized phosphors. [ABSTRACT FROM AUTHOR]

A simple ethylenediamine-assisted hydrothermal method was developed for the synthesis of sheet-like PbS nanostructures. Studies show that ethylenediamine not only provides a weakly basic environment for the reaction system, but also acts as a capping reagent to control the growth habit of cubic PbS. A reasonable growth mechanism for the PbS nanosheet structure has been proposed on the basis of the experimental studies. The structure, morphology, and composition of the nanosheets have been characterized by X-ray powder diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. [ABSTRACT FROM AUTHOR]

PbS-Au heterodimer with Au nanoparticles grown on the tips of PbS nanooctahedrons has been successfully fabricated in ethylene glycol by a facile one-pot method. The morphology of the heterodimers could be changed by the displacement of the capping agent. The products were characterised by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometer analysis and UV-vis absorption spectra. Compared with traditional synthesis methods of the heterodimers, the one-pot process is facile for large-scale synthesis. Owing to the charge transition between the heterointerface, a broad absorption peak around 372 nm is observed in UV-vis absorption spectra. [ABSTRACT FROM AUTHOR]

Crystal‐site engineering of hexagonal‐phase NaGdF4:Mn through alkaline‐earth metal (A2+) doping is used to tune the upconversion luminescence of the Mn2+ dopants. Experimental and calculated results show the ability of A2+ doping to alter the occupancy site of Mn2+ ion from Na+ to Gd3+, thus enabling an emission change from green (520 nm) to yellow (583 nm) upon excitation at 980 nm. The yellow emission of Mn2+ shows a long emission lifetime of 65 ms, more than three times longer than the green emission of Mn2+ (20 ms). The combination of tunable long‐lived Mn2+ emission with lanthanide emission at a single‐particle level provides a convenient route to triple transient upconversion color codes upon dynamic excitation, which offers an attractive optical feature particularly suitable for efficient document encoding. [ABSTRACT FROM AUTHOR]

Ag1Pd1 nanoparticles–reduced graphene oxide (Ag1Pd1‐rGO) was used as highly efficient and recyclable catalyst for the chelation‐assisted ortho C−H bond olefination of amides with acrylates in good yields with a broad substrate scope. The catalyst can be recovered and reused at least 5 times without losing its activity. A synergistic effect between the Ag and Pd atoms on the catalytic activity was found, and a plausible mechanism for the AgPd‐rGO catalyzed C−H olefination was proposed. More information can be found in the Communication by X. Liu, W. Zhang et al. on page 17659. [ABSTRACT FROM AUTHOR]