Hydrothermal Growth of Centimeter-Scale CuO Plates: Planar Chromium(III) Oligomer as a Facet-Directing Agent

In this work, a simple hydrothermal method was developed to synthesize CuO plates in centimeter scale for the first time. Plates of up to 20 μm thickness and several square millimeters in area have been prepared. The unusual size was obtained under ultrahigh-concentration NaOH and a planar chromium­(III) oligomer, which served as a new kind of inorganic facet-directing agent. The obtained CuO plates were glossy black, free-standing, and crack-free. The chromium­(III) oligomer offered ideal chemically active sites for adsorbing and confining Cu²⁺ ions. They could be adsorbed on the surface of Cu­(OH)₄^2– clusters via hydrogen-bonding interaction, which thus modified the growth orientation. The as-synthesized centimeter-scale CuO plates could possibly serve as substrates and electronic materials with potential applications

Crystal Shape Tailoring in Perovskite Structure Rare-Earth Ferrites REFeO₃ (RE = La, Pr, Sm, Dy, Er, and Y) and Shape-Dependent Magnetic Properties of YFeO₃

Controllable growth of perovskite oxide with tailored shapes is challenging but promising for shape-dependent physical and chemical property studies and probable applications. In this article, we report a general method for tailoring the crystal shape of perovskite structure rare-earth ferrite (REFeO₃) crystals in hydrothermal conditions. By adjusting the ratio of KOH to urea, various shapes of REFeO₃ crystals can be prepared, such as LaFeO₃ truncated cubes, PrFeO₃ perpendicular cross prisms, SmFeO₃ crossed bars with trustum, DyFeO₃ double pyramids on cubes, ErFeO₃ distorted octahedrons, and YFeO₃ long bars and thick hexagonal elongated plates. Detailed shape tailoring conditions for each phase of the crystals have been discussed clearly. The structure-dependent shape growing mechanism for each REFeO₃ is generally discussed by consideration of the variance of reduced unit cell parameters in reference to the ideal cubic ABO₃ perovskite structure. DyFeO₃ was taken as an example to elucidate the crystal shape formation mechanism based on the Bravais–Friedel–Donnay–Harker theory. The magnetic property of the YFeO₃ crystal shows shape dependence: elongated bars have the highest saturated magnetization, while the lowest coercive field, while the tailored polyhedrons are vice versa. This paper not only builds a general technique for tailoring the crystal shape to various shapes of REFeO₃ crystals but also provides many crystals for further study and application of anisotropy either in physical or in chemical properties

MOESM1 of Chiral polymer modified nanoparticles selectively induce autophagy of cancer cells for tumor ablation

Additional file 1: Figure S1. Stability in different solutions as indicated of l-PAV-AuNPs and d-PAV-AuNPs. (a) Photos and (b) UV–Vis-NIR of l-PAV-AuNPs or d-PAV-AuNPs in different solutions including saline, PBS, cell medium, fetal bovine serum and dilution of whole blood of the mice for 3 days. Figure S2. The toxicity study of l/d-PAV-AuNPs. (a) Dose- and chirality-dependent cytotoxicity of l/d-PAV-AuNPs in MDA-MB-231 cells, 3T3 fibroblasts and HBL-100 cells respectively. (b) Apoptosis rates of the MDA-MB-231 cells, 3T3 fibroblasts and HBL-100 cells treated with PAV-AuNPs, respectively. FCM analysis was tested via Annexin V-FITC and PI as probes. (c) Expression levels of LC3 in MDA-MB-231 cells, 3T3 fibroblasts and HBL-100 cells with PAV-AuNPs treatment, separately. GAPDH was used as a loading control. Figure S3. Biodistribution of PAV-AuNPs in vivo. The in vivo biodistribution of PAV-AuNPs was analyzed by testing the Au content in main organs (liver, kidneys, spleen, heart, and lung) of mice at 1 and 30 days post intravenous injection, separately. * and ** present p < 0.05 and p < 0.01, respectively

Ultrafast Imaging of Carrier Transport across Grain Boundaries in Hybrid Perovskite Thin Films

For optoelectronic devices based on polycrystalline semiconducting thin films, carrier transport across grain boundaries is an important process in defining efficiency. Here we employ transient absorption microscopy (TAM) to directly measure carrier transport within and across the boundaries in hybrid organic–inorganic perovskite thin films for solar cell applications with 50 nm spatial precision and 300 fs temporal resolution. By selectively imaging sub-bandgap states, our results show that lateral carrier transport is slowed down by these states at the grain boundaries. However, the long carrier lifetimes allow for efficient transport across the grain boundaries. The carrier diffusion constant is reduced by about a factor of 2 for micron-sized grain samples by the grain boundaries. For grain sizes on the order of ∼200 nm, carrier transport over multiple grains has been observed within a time window of 5 ns. These observations explain both the shortened photoluminescence lifetimes at the boundaries as well as the seemingly benign nature of the grain boundaries in carrier generation

Eliminating Nanocrystal Surface Light Loss and Ion Migration to Achieve Bright Mixed-Halide Blue Perovskite LEDs

Blue light-emittin g diodes (LEDs) are important components for perovskite electroluminescence applications, which still suffer from insufficient luminescence efficiency and poor stability. In Cl/Br mixed perovskite NCs, surficial defects cause severe light failure and ion migration, the in-depth mechanism of which is also not clear. To gain insights into these issues, we employ the ligand post-addition approach for mixed Cl/Br NCs by using octylammonium hydrobromide (OctBr) ligands, which effectively decrease surficial light loss and block ion migration pathways. The passivated CsPbCl1.5Br1.5 NCs exhibit exceptional blue emission with 95% PLQY, and the electroluminescence spectra of LEDs are located at the initial positions at the initial states. The treated NC blue devices show a negligible color shift as the voltage increases, which proves that electric-field-driven ion migration is drastically suppressed. In addition, OctBr-treated CsPbCl1.5Br1.5 and CsPbClBr2 NC LEDs show high external quantum efficiencies of 2.42 and 3.05% for emission peaks at 456 and 480 nm, respectively. Our work identified the nature of NC surface defects and provided a surficial modification approach to develop high-performance and color-stable blue mixed-halide perovskite LEDs

δ‑MnO₂–Mn₃O₄ Nanocomposite for Photochemical Water Oxidation: Active Structure Stabilized in the Interface

Pure phase manganese oxides have been widely studied as water oxidation catalysts, but further improvement of their activities is much challenging. Herein, we report an effective method to improve the water oxidation activity by fabricating a nanocomposite of Mn₃O₄ and δ-MnO₂ with an active interface. The nanocomposite was achieved by a partial reduction approach which induced an in situ growth of Mn₃O₄ nanoparticles from the surface of δ-MnO₂ nanosheets. The optimum composition was determined to be 38% Mn₃O₄ and 62% δ-MnO₂ as confirmed by X-ray photoelectron spectra (XPS) and X-ray absorption spectra (XAS). The δ-MnO₂–Mn₃O₄ nanocomposite is a highly active water oxidation catalyst with a turnover frequency (TOF) of 0.93 s^–1, which is much higher than the individual components of δ-MnO₂ and Mn₃O₄. We consider that the enhanced water oxidation activity could be explained by the active interface between two components. At the phase interface, weak Mn–O bonds are introduced by lattice disorder in the transition of hausmannite phase to birnessite phase, which provides active sites for water oxidation catalysis. Our study illustrates a new view to improve water oxidation activity of manganese oxides

Shape Control of Ternary Sulfide Nanocrystals

Synthesis of semiconductor nanocrystals with a definite shape is the foundation of their anisotropy properties investigation; however, it is more challenging in ternary metal sulfides than that of noble metal and binary sulfides. In this paper, we report a solvent polarity control strategy to prepare a family of ternary sulfide (Ag₃SbS₃) semiconductor nanocrystals with tunable polyhedral shapes. The crystal growth speed along different directions was confined by the capping effect of the polarity of solvents that was defined by reaction temperature. Crystal shape of Ag₃SbS₃ nanocrystals could be tailored as a sphere, hexagonal plate, and prism. A shape-controllable growth mechanism was analyzed based on the Bravais–Friedel–Donnay–Harker theory by taking crystal structure characteristics and the polarity of solvents into consideration. The semiconductor nanocrystals show a near value of the band gaps for different shaped samples and facet-dependent photocatalytic water-splitting activities, which may result from the discrimination of the terminal surface structure and binding energy of Sb and S for the three different shaped nanocrystals. Thus, we provide a new crystal shape tunable strategy for ternary sulfide nanocrystal synthesis, which is important for optimizing properties and applications of sulfide semiconductor nanocrystals

MOESM3 of Tumor-infiltrating CD4+ T cells in patients with gastric cancer

Additional file 3: Figure S3. Effects of PD-1+ and Tim-3+ inhibition on IFN-Îł induction. (A) Flow cytometry results; (B) IFN-Îł induction on CD4+ cells

Pressure-Engineered Ti₃C₂T_x MXene with Enhanced Conductivity and Accelerated Reaction Kinetics of Lithium Storage

We studied the structure–function relationship of compressed Ti3C2Tx MXene using high-pressure in situ synchrotron radiation, impedance spectroscopy, Hall effect measurements, and first-principles calculations. With increasing pressure, the conductivity of Ti3C2Tx MXene increases along with its continued lattice shrinkage. A pressure range of 0.4–2.2 GPa exhibits a sharp decrease in resistance, which decreases by more than one order of magnitude from 3.3 × 104 to 1.4 × 103 Ω. A pressure range of 2.2–6.6 GPa exhibits a steady resistance with a slight decrease of 0.2%. As the pressure drops to atmospheric conditions, the resistance increases slightly to 4.2 × 103 Ω. This is accompanied by a transformation of the semiconductor into metal. An irreversible increase in conductivity is observed owing to an increase in the electron concentration and a decrease in the grain-boundary potential barrier. Furthermore, abundant Ti3C2Tx undergoing prepressure treatments (0.4, 2.0, and 4.0 GPa) was first prepared using a double-anvil hydraulic press. The recycled samples retain an accordion-like layered structure with slight lattice shrinkage while the voids between the sheets contract considerably, increasing the density. Correspondingly, electrochemical results show a pressure threshold of 2.0 GPa based on the rapid quenching from the hydraulic press. This weakens the electric polarization in redox reactions and increases the ionic transport rate for the formation of a Ti3C2Tx anode owing to pressure improving the conductivity and interlaminar densification. Our study shows a new, simple, and universal way to regulate various MXenes and also promotes the application of MXene-based materials in energy storage and related fields

Cation Segregation of A‑Site Deficiency Perovskite La_0.85FeO_3−δ Nanoparticles toward High-Performance Cathode Catalysts for Rechargeable Li‑O₂ Battery

Cation segregation of perovskite oxide is crucial to develop high-performance catalysts. Herein, we achieved the exsolution of α-Fe₂O₃ from parent La_0.85FeO_3−δ by a simple heat treatment. Compared to α-Fe₂O₃ and La_0.85FeO_3−δ, α-Fe₂O₃-LaFeO_3–<i>x</i> achieved a significant improvement of lithium-oxygen battery performance in terms of discharge specific capacity and cycling stability. The promotion can be attributed to the interaction between α-Fe₂O₃ and LaFeO_3–<i>x</i>. During the cycling test, α-Fe₂O₃-LaFeO_3–<i>x</i> can be stably cycled for 108 cycles at a limited discharge capacity of 500 mAh g^–1 at a current density of 100 mA g^–1, which is remarkably longer than those of La_0.85FeO_3−δ (51 cycles), α-Fe₂O₃ (21 cycles), and mechanical mixing of LaFeO₃ and α-Fe₂O₃ (26 cycles). In general, these results suggest a promising method to develop efficient lithium-oxygen battery catalysts via segregation