Latest ArticlesAprotic Li-CO2 batteries have attracted growing interest due to their high theoretical energy density and its ability to use green house gas CO2 for energy storage. However, the poor ability of activating CO2 in organic electrolyte often leads to the premature termination of CO2 reduction reaction (CO2RR) directly. Here in this work, cetyl trimethyl ammonium bromide (CTAB) was introduced into a dimethyl sulfoxide (DMSO) based Li-CO2 battery for the first time to enhance the CO2RR. Significantly improved electrochemical performances, including reduced discharge over-potential and increased discharge capacity, can be achieved with the addition of CTAB. Ab initio molecular dynamics (AIMD) simulations show that quaternary ammonium group CTA+ can accelerate CO2 reduction process by forming more stable contact ion pair (CIP) with CO2-, reducing the energy barrier for CO2RR, thus improving the CO2 reduction process. In addition, adding CTA+ is also favorable for the solution-phase growth of discharge products because of the improved migration ability of stable CTA+-CO2- CIP in the electrolyte, which is beneficial for improving the utilization ratio of cathode. This work could facilitate the development of CO2RR by providing a novel understanding of CO2RR mechanism in organic system.
The catalytic elimination of nitrogen-containing volatile organic compounds (NVOCs) still encounters bottlenecks in NOx formation and low N2 selectivity. Here, a series of Cu-promoted Ce-Zr mixed oxide catalysts were synthesized using a simple precipitation approach, and n-butylamine was adopted as the probe pollutant to evaluate their catalytic performance. The CeCu10%ZrOx catalyst exhibited the best catalytic activity, with 100% n-butylamine conversion and 90% N2 selectivity at 250 ℃. Concurrently, this sample also displayed good water resistance. A detailed characterization of the catalyst was performed through a series of experimental studies and theoretical calculations. The addition of Cu increased the redox property and promoted the production of oxygen vacancies, all of which were favorable for the greatest n-butylamine selective catalytic oxidation performance. The changes of oxygen vacancies over CeCu10%ZrOx in reaction process were studied by in situ Raman spectra. Moreover, in situ diffuse reflectance infrared Fourier transform spectra (DRIFTs) and theoretical calculations were employed to explore the reaction mechanism of n-butylamine selective oxidation. The high activity and selectivity of this catalyst confirm the practical feasibility of the selective oxidation of n-butylamine to CO2 and N2, and the exploration of the reaction mechanism provides new insights into the further design of catalysts.
Uncontrollable hemorrhage remains staple trouble in surgical procedures and a leading cause after major trauma. The bleeding issue may trigger various pathologic scenarios that can lead to tissue morbidities and mortalities, and currently available on-site hemostatic agents are confined to a narrow therapeutic index and may carry the risk of immunogenicity. Inspired by the crucial role of platelets in the process of thrombus, a platelet-mimetic plateletsome with wound targeting and blood coagulation properties is developed for hemorrhage control. Plateletsome is formulated by integrating platelet membranes with functionalized synthetic liposomes and exhibits superior wound targeting and effective hemostasis properties. It presents less blood loss and shorter hemostasis time than the platelet membrane vehicles or the conventional liposomes in the mouse tail transection model. The strong homing of the biomimetic plateletsome to the thrombus was also confirmed, demonstrating the potential of this engineered cell membrane vesicle as a biomimetic hemostat for bleeding treatment.
Owing to the exorbitant overpotential and serious carrier recombination of graphitic carbon nitride (g-C3N4), noble metal (NM) is usually served as the H2 evolution co-catalyst. Although the NM (such as Pt) nanoparticles can reduce the H2 evolution overpotential, the weak van der Waals interaction between Pt and g-C3N4 makes against the charge transfer. Herein, the solvothermal method is developed to achieve semi-chemical interaction between Pt and g-C3N4 nanotube (Pt-CNNT) for fast charge transfer. Moreover, the generated in-plane homojunction of CNNT can accelerate charge separation and restrain recombination. Meanwhile, the metallic Pt is an excellent H2 evolution co-catalyst. Photo/electrochemical tests verify that the semi-chemical interaction can improve photogenerated charge separation and transferability of CNNT. As a result, the photocatalytic H2 evolution turnover frequency (TOF) of Pt-CNNT under visible light irradiation reaches up to 918 h−1, which is one of the highest in the g-C3N4-based photocatalysts. This work provides a new idea to improve the charge transfer for efficient photocatalytic H2 evolution.
A gold nanoparticle (AuNP) aggregation-induced colorimetric aptasensing method for quantitative detection of sulfadimethoxine (SDM) with a smartphone was developed. AuNPs were complexed with aptamers which protected AuNPs from aggregating in high-concentration salt solutions. In the presence of SDM, SDM bound with the aptamer on the surface of AuNPs with higher affinity, which competitively desorbed the aptamer from the AuNP surface and resulted in AuNPs aggregation, accompanied with a color change from red to purple-blue. The R, G and B values of images taken by a smartphone camera were analyzed with an app on the smartphone, and were utilized for quantitative analysis of SDM. Under the optimized conditions, the colorimetric aptasensing method using a smartphone showed high sensitivity for SDM, with the limit of detection of 0.023 ppm, lower than the allowed maximum SDM residue limit. This study provides a simple, fast, and easy to read method for on-site quantitative biochemical and cellular analysis.
The photocatalytic reduction of CO2 to energy-rich chemicals is highly appealing for alleviation of energy crisis and environment pollution. The introduction of different active sites is a key factor to determine the reaction activity and selectivity. Here, we demonstrate the metal ion-dependent performance for photocatalytic CO2 reduction by anchoring transition metal ions (Co2+ and Ni2+) in an amine-functionalized boron imidazolate framework (BIF-43). As a result, Ni@BIF-43 realized a high selectivity of 90.2% for the CO2-to-CO, while Co@BIF-43 achieved more efficient conversion with a high CO production rate of 2036.0 µmol g−1 h−1. Significantly, precise control of isolated metal site on a well-defined structure through coordination-assisted strategies enables us to better understand the specific effects of different metal-ion species on photoreduction of CO2 as well as the catalytic mechanism.
Medical cotton dressing is cheap and widely used in diversified fields, but in the application of promoting wound healing, the continuous research of multifunctional medical cotton dressing is still of great significance. Here, we developed a fresh type of antibacterial cotton dressing through a succinct strategy based on chemically anchoring polyhexamethylene biguanide (PHMB). Intriguingly, after PHMB modification, the cotton dressing exhibited outstanding antibacterial performance which could maintain > 99.99% antibacterial rate after several treatments, including washing 50 times, repeated use 10 times, UV irradiation for 7 days, cationic dyes dying, and conditioned under 90 ℃ water bath for 2 h. In addition, the water contact angle of cotton dressing increased dramatically from 0° to 111°, which could facilitate bacterial adhesion, thus further enhance the antibacterial efficiency, and easily remove the bacterial debris. Apart from that, the developed cotton dressing showed good cytocompatibility, promoted blood clotting and expression of platelets, and promoted the wound healing process in the infection intervened skin wound model. Taken together, this antibacterial cotton dressing with desirable blood clotting, sustained protection against bacterial infection and bacterial removal features shows the potential to be a candidate for infected skin wound healing.
Waste utilization is not only the protection of the environment and the practice of green chemistry, but also one of the ways to develop new materials. Herein, we report two biomass carbon dots which prepared from bee pollen waste by one-step hydrothermal method. The new two carbon dots were used in sensing, cell imaging and plant growth regulation. The differences in the structure and properties of the two carbon dots were evaluated by TEM, XPS, TG and various spectroscopic methods. Both two carbon dots contain abundant functional groups, polyatomic doping, excellent water solubility and stable photoluminescence. Due to these good properties, we have demonstrated its versatile applications in Fe3+ sensing, cell imaging and plant growth regulation. It shows sensitive and specific Fe3+ responsiveness and good biocompatibility. This research provides a green and simple method for the recycling and reuse of bee pollen waste, and also provides a reference for the application of biomass carbon dots.
In this work, we developed a novel photoelectrochemical (PEC) sensor based on n-p organic semiconductor heterojunction for sensitive detecting MCF-7 cancer cells. BTA-C4Ph and PM6 were designed as photoactive materials to form n-p heterojunction, which greatly enhanced the photoelectric conversion efficiency. Antibody-modified magnetic nanoparticles were utilized to capture and separate MCF-7 cells from samples. Detection of MCF-7 is ascribed to the loading of MCF-7 onto BTA-C4Ph-PM6 modified electrode that resulted in the decrease of photocurrent intensity. The PEC immunosensor displayed a linear concentration ranging from 50 cell/mL to 1 × 104 cell/mL with a limit of detection (LOD) of 41 cell/mL (S/N = 3) for MCF-7. Additionally, the senor also exhibited good stability, excellent selectivity and prominent reproducibility. Furthermore, the sensor was successfully applied to detect MCF-7 in whole blood. This work illustrates that n-p heterojunction of organic semiconductor may find wide applications for the preparation of different photoelectrochemical sensors.
The first example of stereoconvergent 1, 3-dipolar cycloaddition of nitrile oxides and nitrile imines with E/Z isomeric mixture of electron-deficient olefins is reported, delivering isoxazolines and pyrazolines bearing two vicinal stereogenic tertiary and trifluoromethylated quaternary carbon centers with perfect regio- and diastereoselectivities. The possibility of concerted cycloaddition/epimerization sequence under basic condition to form the thermodynamically stable diastereomers is excluded through some control experiments and DFT calculations, and a stepwise mechanism is proposed.
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