The fundamental role of halide anions in the seed-mediated synthesis of anisotropic noble metal nanostructures has been a subject of debate within the nanomaterials community. Herein, we systematically investigate the roles of chloride, bromide and iodide anions in mediating the growth of anisotropic Au nanostructures. A high-purity surfactant solution of hexadecyltrimethylammonium bromide (CTABr) is used to reliably probe the role of each halide anion without interference from impurities. Our investigation reveals that bromide anions are required for the formation of Au nanorods, while the controlled combination of both bromide and iodide anions are necessary for the production of high-quality Au nanoprisms. Chloride anions, however, are ineffective at promoting anisotropic architectures and are detrimental to nanorod and/or nanoprism growth at high concentrations. We examine the seed structure and propose a growth model based on facet-selective adsorption on low-index Au facets to rationalize the nanostructures obtained by these methods. Our approach provides a facile synthesis of anisotropic Au nanostructures by way of a single growth solution and yields the desired morphologies with high purity. These results demonstrate that appropriate combinations of halide anions provide a versatile paradigm for manipulating the morphological distribution of Au nanostructures.

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Poor stability has long been one of the key issues that hinder the practical applications of lead-based halide perovskites. In this paper, the photoluminescence (PL) quantum yield (QY) of bromide-based perovskites can be increased from 2.5% to 71.54% by introducing water, and the PL QY of a sample in aqueous solution decreases minimally over 1 year. The enhanced stability and PL QY can be attributed to the water-induced methylamino lead bromide perovskite (MAPbBr 3)@PbBr(OH). We note that this strategy is universal to MAPbBr 3 , formamidine lead bromide perovskite (FAPbBr 3), inorganic lead bromide perovskite (CsPbBr 3), etc. Light-emitting devices (LEDs) are fabricated by using the as-prepared perovskite as phosphors on a 365 nm UV chip. The luminance intensity of the LED is 9549 cd/m 2 when the driven current is 200 mA, and blemishes on the surface of glass are clearly observed under the illumination of the LEDs. This work provides a new strategy for highly stable and efficient perovskites.

Water-soluble red afterglow imaging agents based on ecofriendly nanomaterials have potential application in timegated afterglow bioimaging due to their larger penetration depth and nondurable excitation. Herein, red afterglow imaging agents consisted of Rhodamine B (RhB) and carbon nanodots (CNDs) have been designed and demonstrated. In these agents, CNDs act as energy donors, and RhB acts as an energy acceptor. Both of them are confined into a hydrophilic silica shell to form a CNDs-RhB@silica nanocomposite. The phosphorescence emission spectrum of the CNDs and the absorption spectrum of the RhB match well, and efficient energy transfer from the CNDs to the RhB via Forster resonant energy transfer process can be achieved, with a transfer efficiency can reach 99.2%. Thus, the as-prepared nanocomposite can emit a red afterglow in aqueous solution, and the afterglow spectrum of CNDs-RhB@silica nanocomposite can extend to the first near-infrared window (NIR-I). The luminescence lifetime and afterglow quantum yield (QY) of the CNDs-RhB@silica can reach 0.91 s and 3.56%, respectively, which are the best results in red afterglow region. Time-gated in vivo afterglow imaging has been demonstrated by using the CNDs-RhB@silica as afterglow agents.

Solid-state dielectric film capacitors with high-energy-storage density will further promote advanced electronic devices and electrical power systems toward miniaturization, lightweight, and integration. In this study, the influence of interface and thickness on energy storage properties of SrTiO (STO) films grown on LaSrMnO (LSMO) electrode are systematically studied. The cross-sectional high resolution transmission electron microscopy reveals an ion interdiffusion layer and oxygen vacancies at the STO/LSMO interface. The capacitors show good frequency stability and increased dielectric constant with increasing STO thickness (410-710 nm). The breakdown strength (E) increases with decreasing STO thickness and reaches 6.8 MV/cm. Interestingly, the E under positive field is enhanced significantly and an ultrahigh energy density up to 307 J/cm with a high efficiency of 89% is realized. The enhanced E may be related to the modulation of local electric field and redistribution of oxygen vacancies at the STO/LSMO interface. Our results should be helpful for potential strategies to design devices with ultrahigh energy density.

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quantum yield (PL QY) of 93.3%; the highest yield to date among the blue-emitting CDs. [21] Sun and co-workers developed a CD synthesis technique using multicolored emission through controlled graphitization and surface functionalization. [1] They found the CD emission band to be tunable from 430 nm to 630 nm, which covers the blue and red region.Despite such large progress achieved for CD synthesis, plenty of barriers still exist to CD commercialization. Typically, CDs with great performance are primarily prepared through solvothermal routes, meaning at least several hours are needed to prepare CDs at milligram levels. [1,3,4,6,[19][20][21][22][23] Nevertheless, expensive precursors and complex purification processes will no doubt enlarge the construction costs and increase the preparation time. [3][4][5][6] In another way, CDs suffer from aggregation-causedquenching (ACQ) due to π-π stacking in the solid state, which has shown to greatly hinder the application of CDs in light-emitting fields. [24][25][26][27][28] To overcome this deficiency, efforts have been targeted to develop solid CDs with efficient fluorescence by way of CD monomer separation from direct contact, including CD implantation inside polymer matrices and combining them with inorganic salts as composites. [29][30][31][32][33][34][35][36][37][38] Although this effectively prevents the ACQ of CDs in solid state by the dispersal of CDs into various matrices, only CDs at lower loading fractions (i.e., <0.2 wt%) have the ability to achieve high PL QY. [39] While most white LEDs (WLEDs) are created using the one-step synthesis of white light-emitting CDs, the down-conversion fluorescent powders usually suffer from low luminous efficiency or color instability. [40][41][42] Therefore, it is paramount to develop solid CDs with high fluorescence efficiency and stability in facile, low cost, and high-output ways in order to satisfy scale-up industrial production and application.In this study, we report a facile one-step microwave-assisted heating method to prepare solid CDs with strong green emissions. Here, citric acid, urea, and sodium hydroxide (NaOH) have been used as precursors. The CDs were also made to be resistant to self-quenching by in situ embedding the CD into the crystal matrix of NaOH, so that the PL QY could reach 75.9% in the solid state. To the best of our knowledge, this is the highest value attained for solid CDs having green emission. [8,32,[35][36][37][38] Moreover, powdered CD (CDPs) would also have the potential to be prepared on a much larger scale in several minutes It still remains a challenge to synthesize solid-state carbon dots (CDs) with high emission efficiency; a hurdle that has hindered the application of CDs in many fields. In this work, efficient fluorescent CDs have been prepared through a one-step microwave-assisted heating method. Experimental data show strong green emissions produced from the CD powders (CDPs), carrying an unprecedented 75.9% quantum yield due to both spatial confinement and defect reduction with the ...

Brain-inspired computing architectures attempt to emulate the computations performed in the neurons and the synapses in the human brain. Memristors with continuously tunable resistances are ideal building blocks for artificial synapses. Through investigating the memristor behaviors in a LaSrMnO/BaTiO/LaSrMnO multiferroic tunnel junction, it was found that the ferroelectric domain dynamics characteristics are influenced by the relative magnetization alignment of the electrodes, and the interfacial spin polarization is manipulated continuously by ferroelectric domain reversal, enriching our understanding of the magnetoelectric coupling fundamentally. This creates a functionality that not only the resistance of the memristor but also the synaptic plasticity form can be further manipulated, as demonstrated by the spike-timing-dependent plasticity investigations. Density functional theory calculations are carried out to describe the obtained magnetoelectric coupling, which is probably related to the Mn-Ti intermixing at the interfaces. The multiple and controllable plasticity characteristic in a single artificial synapse, to resemble the synaptic morphological alteration property in a biological synapse, will be conducive to the development of artificial intelligence.