Latest ArticlesO3-type layered oxide cathodes have been widely investigated due to their high reversible capacities and sufficient Na+ reservoirs. However, such materials usually suffer from complex multistep phase transitions along with drastic volume changes, leading to the unsatisfied cycle performance. Herein, we report a Mg/Ti co-doped O3-type NaNi0.5Mn0.5O2, which can effectively suppress the complex multistep phase transition and realize a solid-solution reaction within a wide voltage range. It is confirmed that, the Mg/Ti co-doping is beneficial to enhance the structural stability and integrity by absorbing micro-strain and distortions. Thus, the as obtained sample delivers an outstanding cyclic performance (82.3% after 200 cycles at 1 C) in the voltage range of 2.0–4.0 V, and a high discharge capacity of 86.6 mAh/g after 100 cycles within the wide voltage range (2.0–4.5 V), which outperform the existing literatures. This co-doping strategy offers new insights into high performance O3-type cathode for sodium ion batteries.
Strand displacement reaction is a crucial component in the assembly of diverse DNA-based nanodevices, with the toehold-mediated strand displacement reaction representing the prevailing strategy. However, the single-stranded Watson-Crick sticky region that serves as the trigger for strand displacement can also cause leakage reactions by introducing crosstalk in complex DNA circuits. Here, we proposed the toeless and reversible DNA strand displacement reaction based on the Hoogsteen-bond triplex, which is compatible with most of the existing DNA circuits. We demonstrated that our proposed reaction can occur at pH 5 and can be reversed at pH 9. We also observed an approximately linear relationship between the degree of reaction and pH within the range of pH 5–6, providing the potential for precise regulation of the reaction. Meanwhile, by altering the sequence orientation, we have demonstrated that our proposed reaction can be initiated or regulated through the same toeless mechanism without the requirement for protonation in low pH conditions. Based on the proposed reaction principle, we further constructed a variety of DNA nanodevices, including two types of DNA logic gates that rely on pH 5/pH 9 changes for initiating and reversing: the AND gate and the OR gate. We also successfully constructed a DNA Walker based on our proposed reaction modes, which can move along a given track after the introduction of a programmable DNA sequence and complete a cycle after 4 steps. Our findings suggest that this innovative approach will have broad utility in the development of DNA circuits, molecular sensors, and other complex biological systems.
Catalytic enantioselective alkenylation is an efficient method to construct chiral alkene molecules, but the asymmetric alkenylation of simple alkenes catalyzed by metal-free catalysts remains an elusive challenge. Herein, we reported an asymmetric alkenylation of benzoxazinones with diarylethylenes by utilizing a B(C6F5)3/chiral phosphoric acid catalyst. A broad of benzoxazinones and diarylethylenes with electron-withdrawing and electron-donating groups were tolerated (up to 95% yield and 97.5:2.5 e.r.) in the methodology under mild reaction conditions. Moreover, the synthetic utility was confirmed by the scaled-up reaction and transformations of the products. The mechanism was preliminarily explored by control reactions, nonlinear effect experiment and DFT calculations.
A novel citric acid-modified chitosan gel (CSCA) was synthesized through a simple one-step process and was used to extract thorium ions from wastewater. The CSCA samples with varying chemical compositions were analyzed using SEM with mapping EDS, FT-IR, and static water contact angle measurements, and their adsorption behaviors were studied in detail. The results showed that the adsorption performance of CSCA improves with the increase of CA content in the sample. CSCA possesses an impressive capacity for thorium adsorption of 279.8 mg/g. Furthermore, it showed an ultra-fast adsorption rate and reached equilibrium within 30 min. In terms of recyclability, the CSCA still retained more than 86% of its initial adsorption capacity after 6 cycles of reuse. Density functional theory (DFT) analysis reveals that the good selectivity of this material towards thorium ions should be attributed to the high density of adsorption sites and strong interaction between carboxyl groups and thorium ions. This work could be beneficial in the design and synthesis of new polymer materials for extracting thorium.
The relationship mechanism between the material pore structures and cathodic iodine chemistry plays a vital role in efficient Zn-I2 batteries, but is unclear, retarding further advances. This work innovatively indicates a great contribution of ~2.5 nm pore structure of nanocarbons to efficient iodine adsorption, rapid I− ↔ I2 conversion, and polyiodide inhibition, via scrupulously designing catalysts with controllable pore sizes systematically. The I2-loading within the designed nitrogen-doped nanocarbons can reach up to as high as 60.8 wt%. The batteries based on the cathode deliver impressive performances with a large capacity of 178.8 mAh/g and long-term cycling stability more than 4000 h at 5.0 C. Notably, these is no polyiodide such as I3− and I5− detected during the charge-discharge processes from comprehensive electrochemical cyclic voltammetry, X-ray photoelectron spectroscopy, and Raman technique. This work provides a novel knowledge-guided concept for rational pore design, promising better Zn-I2 batteries, which is also hoped to benefit other advanced energy technologies, such as Li–S, Li-ion, and Al–I2 batteries.
Due to its high operational voltage and energy density, P2-type Na0.67Ni0.3Mn0.7O2 has become a leading cathode material for sodium-ion batteries (SIBs), which is an ideal option for large-scale energy storage. However, the practical application of P2-type Na0.67Ni0.3Mn0.7O2 is limited by the capacity constraints and unwanted phase transitions, presenting significant challenges to the widespread application of SIBs. To address these challenges and optimize the electrochemical properties of the P2 phase cathode material, this study proposes a Cu and Zn co-doped strategy to improve the electrochemical performance. The incorporation of Cu/Zn can stabilize the P2-phase structure against P2-O2 phase transitions, thus enhancing its electrochemical properties. The as-obtained P2-type Na0.67[Ni0.3Mn0.58Cu0.09Zn0.03]O2 cathode material shows an impressive cycling stability, maintaining 80% capacity retention after 1000 cycles at 2 C. The cyclic voltammetry (CV) tests show that the Cu2+/Cu3+ redox reaction is also involved in charge compensation during the charge/discharge process.
AIEgens can serve as an effective platform for the construction of photosensitizer-based immunogenic cell death (ICD) inducers. To date, several mitochondria or endoplasmic reticulum (ER)-targeted aggregation-induced emission (AIE) molecules have been developed and have evoked massive ICD in cells. However, due to the complex physicochemical environment in cells, these small AIE molecules cannot maintain a stable aggregate state, which not only affects the fluorescence intensity of the photosensitizer but also decreases the generation of reactive oxygen species (ROS), and thus reducing the effect of the photosensitizer to elicit ICD. AIEgen-based nanomicelles, which maintain a stable micellar structure, can prevent defects of AIE molecules in photodynamic therapy (PDT) applications. Therefore, in this study, a mitochondria-targeted AIE nanophotosensitizer was synthesized and used as a highly potent ICD inducer for vaccine preparation and tumor prevention.
The platinum-based chemotherapy is a routine strategy for the treatment of ovarian cancer, while it is prone to chemoresistance in clinical, which hinders the treatment. Therefore, it is urgently needed to elucidate the underlying mechanism of drug resistance and form the appropriate strategy. The sequencing results showed that cisplatin (DDP) resistant ovarian cancer overexpressed BTB and CNC homology 1 (BACH1), and up-regulated the “don't eat me” signal CD47. We identified that hemin, a BACH1 inhibitor, could effectively down-regulate BACH1 and simultaneously inhibit CD47. Moreover, hemin has a synergistic effect with DDP. We designed a pH-responsive nanoparticle (H/D@FA–CaP–NPs) in which folic acid (FA) ensured targeting of ovarian cancer cells, while hemin inhibited BACH1 as well as down-regulated CD47, achieving the promotion of apoptosis of tumor cells and inducing phagocytosis of tumors by macrophages. Moreover, hemin has a synergistic effect with DDP to promote apoptosis of tumor cells. Structurally, hemin and DDP was encapsulated within hydrophobic 1,2-distearoyl-sn-glycero-3-phospho-ethanolamine (DSPE) to form a tight core, and hydrophilic polyethylene glycol 2000 (PEG2000) and calcium phosphate (CaP) formed the outside shell, and FA was modified on the surface of nanoparticles. In terms of function, (a) FA enhanced the active targeting of nanoparticles to tumors; (b) NPs targeted mitochondria to induce reactive oxygen species (ROS) production; (c) hemin encapsulated in nanoparticles could specifically target BACH1, thereby down regulating CD47; (d) hemin had a synergistic effect with DDP, thus augmenting the chemotherapy. Altogether, mitochondria-targeted nanoparticles H/D@FA–CaP–NPs promoted tumor apoptosis and mobilized phagocytosis to treat tumor, providing a novel scheme for clinical treatment of cisplatin-resistant ovarian carcinoma.
The development of highly efficient catalysts in the cathodes of rechargeable Li-O2 batteries is a considerable challenge. To enhance the electrochemical performance of the Li-O2 battery, it is essential to choose a suitable catalyst material. Copper selenide (CuSe) is considered as a more promising cathode catalyst material for Li-O2 battery due to its better conductivity and rich electrochemical active sites. However, its electrochemical reaction and fundamental catalytic mechanism remain unclear till now. Herein, in-situ environmental transmission electron microscopy technique was used to study the catalysis mechanism of the CuSe nanosheets in Li-O2 batteries during discharge and charge processes. It is found that Li2O was formed and decomposed around the ultrafine-grained Cu during the discharge and charge processes, respectively, demonstrating excellent cycling. This indicate that the freshly formed ultrafine-grained Cu in the conversion reaction catalyzed the latter four-electron-transfer oxygen reduction reaction, leading to the formation of Li2O. Our study provides important understanding of the electrochemistry of the Li-O2 nanobatteries, which will aid the development of high-performance Li-O2 batteries for energy storage applications.
Sulfurized polyacrylonitrile (SPAN) is proposed as a promising cathode material for lithium sulfur batteries. However, the continuous side reactions at the electrolyte-electrode interfaces as well as the slow redox kinetics of SPAN cathode deteriorate the electrochemical performance. In this study, an electrolyte with dual-additives comprising 2-fluoropyridine (2-FP) and lithium difluorobis (oxalato) phosphate (LiDFBOP) was used to improve the performance of Li||SPAN cells. 2-FP has a lower lowest occupied molecular orbital energy than that of the solvents in the electrolyte, leading to its prior reduction. A LiF-rich film can be formed on the electrode, effectively improving the stability of the electrolyte-electrode interfaces and prolonging the life. Simultaneously, LiDFBOP could form an electrolyte-electrode interface film containing a large amount of LixPOyFz species, compensating for the kinetic deterioration caused by the lower ionic conductive of LiF formed at the electrolyte-electrode interface. Hence, an electrode-interface film with good chemical stability and high Li+ transport was established by LiF and LixPOyFz-rich species. The Li||SPAN cell with the electrolyte containing dual-additives demonstrates an excellent capacity retention of 97.5% after 200 cycles at 1.0 C, 25 ℃, comparing to 56.2% capacity retention without additives. Moreover, the rate capacities of cells with dual-additives can reach 1128.1 mAh/g at 5 C, comparing to only 813.5 mAh/g using electrolyte without additives. Our results shown that the dual-additives in electrolyte provide a promising strategy for practical application of lithium sulfur batteries with SPAN cathodes.
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