化学最新文献

Challenges associated with lithium dendrite growth and the formation of dead lithium significantly limit the achievable energy density of lithium metal batteries (LMBs), particularly under high operating current densities. Our innovative design employs a state-of-the-art 2500 separator featuring a meticulously engineered cellulose acetate (CA) coating (CA@2500) to suppress dendrite nucleation and propagation. The CO functional groups in CA enhances charge transfer kinetics and triggering the decomposition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), which leads to the formation of a more robust solid electrolyte interphase (SEI) composed primarily of LiF. Moreover, the introduction of polar functional groups in the CA enhances the separator's hydrophilic properties, facilitating the uniform Li⁺ flux and creating a conductive pathway for efficient lithium migration. As a result, the CA@2500 separator exhibits a high lithium-ion transfer number (0.88) and conductivity. The lithium symmetric cell assembles with the CA@2500 separator displays a stable cycling performance over 5500 h at a current density and capacity of 10 mA cm^-2 and 10 mAh cm^-2, respectively. Additionally, LPF battery with CA@2500 separator shows an excellent capacity retention at 0.2 C with an average decay of 0.055 % per cycle. Moreover, a high capacity of 105 mAh g^-1 is maintained after 500 cycles at 5 C with an average decay of only 0.027 % per cycle. This work achieved high stability of LMBs through simplified engineering.

Designing inexpensive, high-efficiency and durable bifunctional catalysts for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) is an encouraging tactic to produce hydrogen with reduced energy expenditure. Herein, oxygen vacancy-rich cobalt hydroxide/aluminum oxyhydroxide heterostructure on nickel foam (denoted as Co(OH)₂/AlOOH/NF-100) has been fabricated using one step hydrothermal process. Theoretical calculation and experimental results indicate the electrons transfer from Co(OH)₂ to highly active AlOOH results in the interfacial charge redistribution and optimization of electronic structure. Abundant oxygen vacancies in the heterostructure could improve the conductivity and simultaneously serve as the active sites for catalytic reaction. Consequently, the optimal Co(OH)₂/AlOOH/NF-100 demonstrates excellent electrocatalytic performance for HER (62.9 mV@10 mA cm^-2) and UOR (1.36 V@10 mA cm^-2) due to the synergy between heterointerface and oxygen vacancies. Additionally, the in situ electrochemical impedance spectrum (EIS) for UOR suggests that the heterostructured catalyst exhibits rapid reaction kinetics, mass transfer and current response. Importantly, the urea-assisted electrolysis composed of the Co(OH)₂/AlOOH/NF-100 manifests a low cell voltage (1.48 V @ 10 mA cm^-2) in 1 M KOH containing 0.5 M urea. This work presents a promising avenue to the development of HER/UOR bifunctional electrocatalysts.

Easy and effective usage of computational resources is crucial for scientific calculations. Following our recent work of machine-learning (ML) assisted scheduling optimization [J. Comput. Chem. 2023, 44, 1174], we further propose (1) the improved ML models for the better predictions of computational loads, and as such, more elaborate load-balancing calculations can be expected; (2) the idea of coded computation, that is, the integration of gradient coding, in order to introduce fault tolerance during the distributed calculations; and (3) their applications together with re-normalized exciton model with time-dependent density functional theory (REM-TDDFT) for calculating the excited states. Illustrated benchmark calculations include P38 protein, and solvent model with one or several excitable centers. The results show that the improved ML-assisted coded calculations can further improve the load-balancing and cluster utilization, owing primarily profit in fault tolerance that aims at the automated quantum chemical calculations for both ground and excited states.

Recently tetraspanin CD151 has been identified as an important biological target involved in metastatic processes which include cell adhesion, tumor progression processes, and so forth in different types of cancers, such as breast cancer and glioblastoma. This in Silico study considered 1603 compounds from the Food and Drug Administration database, after performing an ADMET analysis; we selected 853 ligands, which were used for docking analysis. The most promising ligands were selected from docking studies, based on two criteria: (a) showed lowest affinity to the CD151 protein and (b) they interact with the QRD motif, located in the second extracellular loop. Furthermore, we investigate the stability of the protein-ligand complexes through MD simulations as well as free energy MM-PBSA calculations. From these results, loperamide and glipizide were identified as the best evaluated drugs. We suggest an in vitro analysis is needed to confirm our in silico prediction studies.

Development of organic nonlinear optical materials has become progressively more important due to their emerging applications in new-generation photonic devices. A novel series of chromophores based on innovative thiophene and furan-fused cyclopentadienyl bridge with various powerful donor and acceptor moieties were designed and theoretically investigated for applications in nonlinear optics. To unravel the structure-property relationship between this new push-pull conjugated systems and their nonlinear optical property, multiple methods, including density of states analysis, coupled perturbed Kohn-Sham (CPKS) method, sum-over-states (SOS) model, the two-level model (TSM), hyperpolarizability density analysis, and the (hyper)polarizability contribution decomposition, were performed to comprehensively investigated the nonlinear optical and electronic properties of this new π-system. Due to excellent charge transfer ability of new bridge and distinctive structure of donor and acceptor, the designed chromophores exhibit deep HOMO levels, low excitation energy, high dipole moment difference and large hyperpolarizability, indicating the appealing air-stable property and remarkable electrooptic performance of them. Importantly, THQ-CS-A3 and PA-CS-A3 shows outstanding NLO response properties with β_tot value of 6953.9 × 10^-30 and 5066.0 × 10^-30 esu in AN, respectively. The influence of the push-pull strength, the heterocycle and the π-conjugation of new bridge on the nonlinear optical properties of this novel powerful systems are clarified. This new series of chromophores exhibit remarkable electro-optical Pockels and optical rectification effect. More interestingly, PA-CS-A3 and THQ-CS-A2 also show appealing SHG effect. This study will help people understand the nature of nonlinear optical properties of innovative heteroarene-fused based cyclopentadienyl chromophores and offer guidance for the rational design of chromophores with outstanding electrooptic (EO) performance in the future.

Chlorine is an important chemical which has long been produced in chlor-alkali process using dimensionally stable anodes (DSA). However, some serious drawbacks of DSA inspire the development of alternative anodes for chlorine evolution reaction (CER). In this study, we focused on the graphene- and carbon nanotube-supported platinum tetra-phenyl porphyrins as electrocatalysts for CER, which have been theoretically investigated based on density functional theory. Our results reveal that the supported substrates possess potential CER electrocatalytic activity with very low thermodynamic overpotentials (0.012-0.028 V) via Cl* pathway instead of ClO*. The electronic structures analyses showed that electron transfer from the support to the adsorbed chlorine via the Pt center leads to strong Pt-Cl interactions. Furthermore, the supported electrocatalysts exhibited excellent selectivity toward CER because of high overpotentials and reaction barriers of oxygen evolution process. Therefore, our results may pave the way for designing CER electrocatalyst utilizing emerging carbon nanomaterials.

The two-dimensional (2D) monolayer material MoSi₂N₄ was successfully synthesized in 2020[Hong et al., Science 369, 670, (2020)], exhibiting a plethora of new phenomena and unusual properties, with good stability at room temperature. However, MA₂Z₄ family monolayer materials involve primarily transition metal substitutions for M atoms. In order to address the research gap on lanthanide and actinide MA₂Z₄ materials, this work conducts electronic structure calculations on novel 2D MSi₂N₄ (M = La, Eu) monolayer materials by employing first-principles methods and CASTEP. High carrier mobility is discovered in the indirect bandgap semiconductor 2D LaSi₂N₄ monolayer (~5400 cm² V^-1 s^-1) and in the spin (spin-down channel) carrier mobility of the half-metallic ferromagnetic EuSi₂N₄ monolayer (~2800 cm² V^-1 s^-1). EuSi₂N₄ monolayer supplements research on spin carrier mobility in half-metallic ferromagnetic monolayer materials at room temperature and possesses a magnetic moment of 5 μ_B, which should not be underestimated. Furthermore, due to the unique electronic band structure of EuSi₂N₄ monolayer (with the spin-up channel exhibiting metallic properties and the spin-down channel exhibiting semiconductor properties), it demonstrates a 100% spin polarization rate, presenting significant potential applications in fields such as magnetic storage, magnetic sensing, and spintronics.

Using embedding methods, compounds with similar properties will be closely located in latent space, and these embedding vectors can be used to find other compounds with similar properties based on the distance between compounds. However, they often require computational resources and programming skills. Here we develop Dr.Emb Appyter, a user-friendly web-based chemical compound search platform for drug discovery without any technical barriers. It uses embedding vectors to identify compounds similar to a given query in the embedding space. Dr.Emb Appyter provides various types of embedding methods, such as fingerprinting, SMILES, and transcriptional response-based methods, and embeds numerous compounds using them. The Faiss-based search system efficiently finds the closest compounds of query in the library. Additionally, Dr.Emb Appyter offers information on the top compounds; visualizes the results with 3D scatter plots, heatmaps, and UpSet plots; and analyses the results using a drug-set enrichment analysis. Dr.Emb Appyter is freely available at https://dremb.korea.ac.kr.

Sensitive monitoring of human 8-oxyguanine DNA glycosylase (hOGG1) activity in living cells is helpful to understand its function in damage repair and evaluate its role in disease diagnosis. Herein, a functional DNA-Zn²⁺ coordination nanospheres was proposed for sensitive imaging of hOGG1 in living cells. The nanospheres were constructed through the coordination-driven self-assembly of the entropy driven reaction (EDR) -deoxyribozyme (DNAzyme) system with Zn²⁺, where DNAzyme was designed to split structure and assembled into the EDR system. When the nanospheres entered the cell, the competitive coordination between phosphate in the cell and Zn²⁺ leaded to the disintegration of the nanospheres, releasing DNA and some Zn²⁺. The released Zn²⁺ acted as a cofactor of DNAzyme. In the presence of hOGG1, the EDR was completed, accompanied by fluorescence recovery and the generation of a complete DNAzyme. With the assistance of Zn²⁺, DNAzyme continuously cleaved substrates to produce plenty of fluorescence signals, thus achieving sensitive imaging of hOGG1 activity. The nanospheres successfully achieved sensitive imaging of hOGG1 in human cervical cancer cells (HeLa), human non-small cell lung cancer cells and human normal colonic epithelial cells, and assayed changes in hOGG1 activity in HeLa cells. This nanospheres may provide a new tool for intracellular hOGG1 imaging and related biomedical studies.

The practical applications of lithium sulfur batteries (LSBs) are hindered by notorious shuttle effect and sluggish conversion kinetics of intermediate polysulfides. Herein, Mo₂C-Co heterogeneous particles decorated two-dimensional (2D) carbon nanosheets grown on hollow carbon microtubes (CCC@MCC) are synthesized. Three-dimensional (3D) carbon framework with Mo₂C-Co heterogeneous particles combines the conductivity, adsorption and catalysis, effectively trapping and accelerating the conversion of polysulfides. As evidenced experimentally, the hetero-structured Mo₂C-Co with high Li⁺ diffusion coefficient enables uniform precipitation and complete oxidation of Li₂S. Meanwhile, CCC@MCC is found to have multiple application possibilities for lithium-sulfur batteries. As an interlayer, the cells deliver an excellent capacity of 881.1 mAh/g at 2C and still retain 438.2 mAh/g after 500 cycles under the low temperature of 0 ℃. As a sulfur carrier, the cell with a sulfur loading of 7.0 mg cm^-2 exhibits a high area capacity of 5.3 mAh cm^-2. This work provides an effective strategy to prepare heterostructured material and imaginatively exploit the application potential of it.