First-Principles Screening of All-Inorganic Lead-Free ABX₃ Perovskites

In order to address an all-inorganic halide lead-free perovskite for potential photovoltaic applications, we carried out first-principles calculations of bandgaps of 260 all-inorganic halide perovskites belonging to the class ABX₃, with A = Li, Na, K, Rb, Cs, B = Pb, Sn, and Ge, and X = F, Cl, Br, I. Three most common crystal symmetries were chosen, including cubic, tetragonal, and two orthorhombic phases. The bandgap exhibited increase with the decreasing of the anions radius (I, Br, Cl, F) and lowering the symmetry of the structures. With consideration of multiple factors forming perovskites, we reported three all-inorganic lead-free halides perovskites including cubic-KSnCl₃, cubic-RbSnCl₃, and trigonal-NaGeBr₃ as candidates with desirable bandgap (1.24–1.44 eV) for photovoltaic applications

Direct Visualization of the Formation about Inverse Catalyst CoO_(<i>x</i>)/Pt(111)

In nonhomogeneous catalysts, the catalyst formation process plays a critical role in determining catalytic performance. However, there is limited research on visualizing the synthesis process on the atomic scale. In this study, we successfully grew cobaltocene films on Pt(111) under ultrahigh vacuum (UHV) conditions using an ultralow temperature atomic layer deposition technique. To simulate real-world conditions, we investigated the effects of oxygen and temperature on cobaltocene (CoCp2) thin films by introducing oxygen into an ultrahigh vacuum chamber. The characterization of the formation process was conducted in detail by scanning tunneling microscopy (STM). Additionally, we elaborate on the entire process of treating Pt single crystals by using the E-beam method. Given the significance of cobaltocene adsorption in the overall process, we investigated its behavior at different exposure times. At an exposure time of 30 s, cobaltocene was observed to be dispersed on the surface as atomic clusters. With longer exposure times, the surface of Pt(111) became fully covered by cobaltocene molecules, reaching a height of about 70 pm. Subsequently, through oxidation annealing in 1 × 10–7 mbar O2 at 673 K, amorphous cobaltocene films were transformed into CoO(x) islands with crystal structures. To assess the stability of CoO(x) islands on Pt(111) at different temperatures, ab initio molecular dynamics (AIMD) and density functional theory (DFT) calculations were performed. Molecular dynamics simulations were performed on the two heterostructures at 623 and 673 K, respectively. After 2000 fs cycles, both the energy and temperature gradually stabilized following a brief oscillation, eventually reaching equilibrium

Boosting the Self-Trapped Exciton Emission in Cs₂NaYCl₆ Double Perovskite Single Crystals and Nanocrystals

Halide double perovskites have aroused substantial research interest because of their unique optical properties and intriguing flexibility for various compositional adjustments. Herein, we report the synthesis and photophysics of rare-earth element yttrium (Y)-based double perovskite single crystals (SCs) and nanocrystals (NCs). The pristine Cs2NaYCl6 bulk SCs exhibit a weak sky-blue emission with a low photoluminescence quantum yield (PLQY) of 7.68% based on the self-trapped exciton (STE), while no PL emission was observed for NCs. Excitingly, the STE emission of SCs and NCs is greatly enhanced via Sb3+ doping. The optimized Cs2NaYCl6:Sb3+ SCs and NCs exhibit high PLQYs up to 82.5% and 51.8%, respectively. Theoretical calculations and charge-carrier dynamic studies demonstrate that the giant emission enhancement after Sb3+ doping is related with the enhancement of the sensitization of the emissive STE states, the passivating of the nonradiative carrier trapping processes, and the regulation of carrier–phonon coupling

Computational Design and Experimental Validation of Enzyme Mimicking Cu-Based Metal–Organic Frameworks for the Reduction of CO₂ into C₂ Products: C–C Coupling Promoted by Ligand Modulation and the Optimal Cu–Cu Distance

While extensive research has been conducted on the conversion of CO2 to C1 products, the synthesis of C2 products still strongly depends on the Cu electrode. One main issue hindering the C2 production on Cu-based catalysts is the lack of an appropriate Cu–Cu distance to provide the ideal platform for the C–C coupling process. Herein, we identify a lab-synthesized artificial enzyme with an optimal Cu–Cu distance, named MIL-53 (Cu) (MIL= Materials of Institute Lavoisier), for CO2 conversion by using a density functional theory method. By substituting the ligands in the porous MIL-53 (Cu) nanozyme with functional groups from electron-donating NH2 to electron-withdrawing NO2, the Cu–Cu distance and charge of Cu can be significantly tuned, thus modulating the adsorption strength of CO2 that impacts the catalytic activity. MIL-53 (Cu) decorated with a COOH-ligand is found to be located at the top of a volcano-shaped plot and exhibits the highest activity and selectivity to reduce CO2 to CH3CH2OH with a limiting potential of only 0.47 eV. In addition, experiments were carried out to successfully synthesize COOH-decorated MIL-53(Cu) to prove its high catalytic performance for C2 production, which resulted in a −55.5% faradic efficiency at −1.19 V vs RHE, which is much higher than the faradic efficiency of the benchmark Cu electrode of 35.7% at −1.05 V vs RHE. Our results demonstrate that the biologically inspired enzyme engineering approach can redefine the structure–activity relationships of nanozyme catalysts and can also provide a new understanding of the catalytic mechanisms in natural enzymes toward the development of highly active and selective artificial nanozymes

Low Threshold Two-Photon-Pumped Amplified Spontaneous Emission in CH₃NH₃PbBr₃ Microdisks

Two-photon-pumped amplified spontaneous emission (ASE) of CH₃NH₃PbBr₃ microdisks (MDs) were investigated by using femtosecond laser system. Low threshold at 2.2 mJ cm^–2 was obtained. Also, emission spectral tunability from 500 to 570 nm was demonstrated by synthesis the mixed halide perovskite MDs. The spatial effect of photoluminescence (PL) properties under one-photon and two-photon excitation were also studied by means of two-photon laser scanning microscope (TPLSM) and time-resolved PL spectroscopy. It was found that the band to band emission of near-surface regions and photocarriers’ diffusion from near-surface regions to interior regions is significant for one-photon excitation. By contrast, reabsorption of emission under two-photon excitation plays a major role in the emission properties of the MDs. These results will give a more comprehensive understanding of the nonlinear effect of CH₃NH₃PbBr₃ single crystals

Paper-Fiber-Activated Triplet Excitons of Carbon Nanodots for Time-Resolved Anti-counterfeiting Signature with Artificial Intelligence Authentication

The easy-to-imitate character of a personal signature may cause significant economy loss due to the lack of speed and strength information. In this work, we report a time-resolved anti-counterfeiting signature strategy with artificial intelligence (AI) authentication based on the designed luminescent carbon nanodot (CND) ink, whose triplet excitons can be activated by the bonding between the paper fibers and the CNDs. Paper fibers can bond with the CNDs through multiple hydrogen bonds, and the activated triplet excitons release photons for about 13 s; thus, the speed and strength of the signature are recorded through recording the changes in luminescence intensity over time. The background noise from commercial paper fluorescence is completely suppressed, benefiting from the long phosphorescence lifetime of the CNDs. In addition, a reliable AI authentication method with quick response based on a convolutional neural network is developed, and 100% identification accuracy of the signature based on the CND ink is achieved, which is higher than that of the signature with commercial ink (78%). This strategy can also be expanded for painting, calligraphy identification

Additional file 1 of Mechanisms of Bushen Tiaoxue Granules against controlled ovarian hyperstimulation-induced abnormal morphology of endometrium based on network pharmacology

Additional file 1: Table S1. Composition of the BTG. Table S2. Identification of chemical components in BTG. Table S3. Affinity of ingredients with potential targets. Figure S1. The blood drug concentration of kaempferol following BTG administration. Kaempferol standard was obtained from MedChemExpress (USA) with a purity of 99.86% (HY-14590). An appropriate amount of kaempferol was added to 75% methanol to prepare a stock solution of 200 μg/mL for the mixed control solution. Upon usage, it was sequentially diluted to obtain concentration gradient solutions. Utilizing the same 50 female SD rats as employed in the in vivo experiment, two rats constituted the blank control group, while the remaining 48 rats were divided into treatment groups, each consisting of 6 rats. The treatment groups received oral gavage of BTG at 3.27 g/kg for 3 consecutive days, while the blank control group received an equivalent volume of physiological saline using the same procedure. Prior to the final dosing, the rats were fasted for 12 hours but allowed access to water. Blood samples were collected from the abdominal aorta of the rats at 8 time intervals post administration (10 min, 20 min, 30 min, 1 h, 2 h, 4 h, 8 h, 12 h) after anesthetizing the rats using 1% pentobarbital sodium. The blood samples were centrifuged at 4°C, 3500 rpm for 10 min, and the supernatant was analyzed. Following the UPLC-MS analysis method described earlier, the peak areas of the analyte and internal standard were recorded to calculate the blood drug concentrations at each time point. Figure S2. The impact of BTG administration on rat liver and kidney function. The serum levels of (A) ALT, (B) AST, (C) CREA, (D) UA, and (E) UREA in each group of rats were measured using microplate assays. The assay kits were obtained from Nanjing Jiancheng Bioengineering Institute (China)

Constructing Sensitive and Fast Lead-Free Single-Crystalline Perovskite Photodetectors

We developed a high-performance photodetector based on (CH₃NH₃)₃Sb₂I₉ (MA₃Sb₂I₉) microsingle crystals (MSCs). The MA₃Sb₂I₉ single crystals exhibit a low-trap state density of ∼10¹⁰ cm^–3 and a long carrier diffusion length reaching 3.0 μm, suggesting its great potential for optoelectronic applications. However, the centimeter single crystal (CSC)-based photodetector exhibits low responsivity (10^–6 A/W under 1 sun illumination) due to low charge-carrier collection efficiency. By constructing the MSC photodetector with efficient charge-carrier collection, the responsivity can be improved by three orders of magnitude (under 1 sun illumination) and reach 40 A/W with monochromatic light (460 nm). Furthermore, the MSC photodetectors exhibit fast response speed of <1 ms, resulting in a high gain of 108 and a gain-bandwidth product of 10⁵ Hz. These numbers are comparable to the lead-perovskite single-crystal-based photodetectors

(C₆H₅C₂H₄NH₃)₂GeI₄: A Layered Two-Dimensional Perovskite with Potential for Photovoltaic Applications

Recently, two-dimensional organic–inorganic perovskites have attracted increasing attention due to their unique photophysical properties and high stability. Here we report a lead-free, two-dimensional perovskite, (PEA)₂GeI₄ (PEA = C₆H₅(CH₂)₂NH₃⁺). Structural characterization demonstrated that this 2D perovskite structure is formed with inorganic germanium iodide planes separated by organic PEAI layers. (PEA)₂GeI₄ has a direct band gap of 2.12 eV, in agreement with 2.17 eV obtained by density functional theory (DFT) calculations, implying that it is suitable for a tandem solar cell. (PEA)₂GeI₄ luminesces at room-temperature with a moderate lifetime, exhibiting good potential for photovoltaic applications. In addition, 2D (PEA)₂GeI₄ is more stable than 3D CH₃NH₃GeI₃ in air, owing to the presence of a hydrophobic organic long chain. This work provides a direction for the development of 2D Ge-based perovskites with potential for photovoltaic applications