Latest ArticlesNative amino-directed palladium-catalyzed C(sp3)–H activation/functionalization has been developed for modification of α-amino acids and peptides. Herein a palladium(Ⅱ)-catalyzed C(sp2)–H arylation of α-amino-β-aryl esters has been disclosed, using the native amino as the directing group. A variety of chiral α-amino-β-aryl esters can be functionalized to give the corresponding ortho-substituted mono- and di-arylated products.
Partial substitution of polyoxometalate (POM) is an efficient route to modulate the catalytic property of maternal POM. In this work, a new Keggin type POM involving {Ni6} cluster, {[Ni(H2O)2(Dach)2][Ni(Dach)2]2}{[Ni6Cl(μ-OH)3(H2O)(Dach)3(WO4)(PW9O34)][Ni6(μ-OH)3(H2O)2(Dach)3(WO4)(PW9O34)]}Cl·27H2O, (1, Dach = 1,2-diaminocyclohexane) was synthesized. Compounds 1 shows excellent catalytic performance in the selective oxidation of aniline to azoxybenzene (AOB) in water. The apparently different results from that with the matrix {PW9O34} ({PW9}) suggest the successful regulation of the catalytic property of {PW9} by the introduction of the {Ni6} cluster into the skeleton. The experimental results indicate that the highlighted performance of 1 is contributed by the synergy of W and Ni sites, which are respectively responsible for the oxidation and condensation steps in the production of AOB. The good selectivity to AOB is essentially attributed to the effective modulation of the reaction rates of oxidation and condensation steps by W and Ni sites, respectively.
One of the urgent and challenging topics in diversified sustainable energy conversion is the development of high-performance, low-cost, and well durable catalysts. Cu single-atom catalysts (SACs) have become promising catalysts for diversified sustainable energy conversion due to their capability to maximize the utilization efficiency, acquire modulated electronic structure and optimized binding strength with intermediates. In this review, we have provided an interview of the recent progress achieved in the field of electrocatalysis, photocatalysis, and heterogeneous reaction based on Cu SACs. Started by this review, we have summarized some advanced synthetic strategies for the construction of Cu SACs. Subsequently, the performance-improving strategies are discussed in terms of the coordination environments of the reaction center, reaction mechanism and selectivity, based on free energy diagram and electron structure analysis. Finally, the remaining issues, challenges, and opportunities of Cu SACs are also provided, affording a perspective for future studies. This review not only offers us a deep understanding on the catalytic mechanism of Cu SACs for energy conversion, but also encourages more endeavors in prompting their practical application.
Bone metastasis, a life-threatening complication of advanced breast cancer, is often accompanied by debilitating pain (cancer-induced bone pain, CIBP) that severely impairs life quality and survival. The concurrent treatment of bone metastases and CIBP remains a clinical challenge because the therapeutic options are limited. In this study, we construct a near-infrared light-activated nano-therapeutic system to meet this conundrum. In detail, sorafenib (SRF) and photosensitizer (chlorin e6, Ce6) are encapsulated into mesoporous hydroxyapatite nanoparticles (HANPs), which are further functionalized with hyaluronic acid (HA) to obtain HA-SRF/Ce6@HANPs system. The designed nanoplatform destroys tumor cells in vitro and in vivo via the synergism of SRF (interrupting the exchange of cystine/glutamate by inhibiting SLC7A11) and photodynamic therapy (PDT, inducing reactive oxygen species generation). The decrease in tumor burden and reduction of extracellular glutamate significantly attenuate CIBP in mice model with developing bone cancer. Moreover, the combination of HA-SRF/Ce6@HANPs and PDT inhibit osteoclasts activation, promote osteoblast differentiation and accelerate bone repair. Overall, the nanoagent with good biocompatibility may provide an effective therapy method for the concurrent treatment of breast cancer bone metastasis and CIBP.
So far, a clear understanding about the relationship of variable energy band structure with the corresponding charge-discharge process of energy storage materials is still lacking. Here, using optical spectroscopy (red-green-blue (RGB) value, reflectivity, transmittance, UV–vis, XPS, UPS) to study α-Co(OH)2 electrode working in KOH electrolyte as the research object, we provide direct experimental evidence that: (1) The intercalation of OH– ions will reduce the valence/conduction band (VB and CB) and band gap energy (Eg) values; (2) The deintercalation of OH– ions corresponds with the reversion of VB, CB and Eg to the initial values; (3) The color of Co(OH)2 electrode also exhibit regular variations in RGB value during the charge-discharge process.
Rechargeable alkaline aqueous zinc batteries (RAZBs) have attracted increasing attention. However, most RAZBs are hindered by the limited availability of cathode materials. The practical electrochemical performance of most cathode materials is lower than the theoretical value due to their poor electrical conductivity and low utilization capacity. In this work, we develop a facile hydrothermal procedure to prepare highly uniform bimetallic sulfides as novel cathode materials for RAZBs. Copper-cobalt binary metallic oxides materials possess higher conductivity and larger capacity compared with their mono-metal oxides compounds due to bimetallic synergistic effects and multiple oxidation states. Furthermore, bimetallic sulfide compounds have smaller bond energy and longer bond length than their oxides, leading to less structural damage, faster kinetics of electrochemical reactions, and better stability. The as-prepared Co-Cu bimetallic sulfides show enhanced electrochemical performance due to various valences of Co and Cu as well as the existence of S. As a result, aqueous Zn/CuCo2S4 battery shows a high specific capacity of 117.4 mAh/g at 4 A/g and a good cycle life of over 8000 cycles. Based on PANa hydrogel electrolytes, a flexible Zn/CuCo2S4 battery demonstrates excellent cycling stability. This battery can also meet the requirements of electronic devices with different shapes and performs well in extreme environments, such as freezing, drilling, and hammering. This work opens new avenues to obtain high-rate and long-life cathode materials for RAZBs by utilizing the synergistic effects of bimetallic sulfides and provides a new platform for flexible energy storage devices.
Rapid analysis of metal ions and organic compounds in strong acidic solutions is of sustainable interest in multiple disciplines. However, complicated and time-consuming pretreatments are always required for MS analysis of the compounds in strong acidic solutions. Otherwise, it will result in a weak signal and cause serious damage to the mass spectrometer. Herein, a simple method inherited from nano-ESI MS was developed for rapid analysis of strong acidic solutions. Nanoliter (nL) strong acidic solution was first loaded in the nano-ESI emitter, followed by evaporation to remove the H+ and leave the analytes on the wall of the nano-ESI emitter. The evaporation process can be completed within 1 min because of the extremely tiny volume (≤1 nL) of the loaded solution. Then, the dried analytes on the wall of the nano-ESI emitter were redissolved by loading a new solvent, followed by nano-ESI MS analysis. By using this method, metal ions and organic compounds in the strong acidic solution can be detected with low sample consumption (1 nL), high speed (< 2 min/sample), high sensitivity (limit of detection = 0.2 µg/L), and high accuracy (> 90%). Proof-of-concept applications of the present method have been successfully achieved for the analysis of gastric juice (pH of the sample = 1), monitoring reaction catalyzed by strong acid (pH of the system = 0), and micro-area analysis of ores (pH of the extraction solvent = 0), showing great application potential in multiple fields.
Establishing an effective charge transfer mechanism in carbon nitride (g-C3N4) to enhance its photocatalytic activity remains a limiting nuisance. Herein, the combination design of a single Cu atom with hollow g-C3N4 nanospheres (Cu-N3 structure) has been proven to offer significant opportunities for this crucial challenge. Moreover, this structure endows two pathways for charge transfer in the reaction, namely, the N atoms in the three-dimensional planar structure are only bonded with a single Cu atom, and charge transfer occurs between the plane and the layered structure due to the bending of the interlayered g-C3N4 hollow nanospheres. Notably, Cu-N3 and hollow nanosphere structures have been certified to greatly enhance the efficiency of photogenerated carrier separation and transfer between the layers and planes by ultrafast spectral analysis. As a result, this catalyst possesses unparalleled photocatalytic efficiency. Specifically, the hydrogen production rate up to 2040 µmol h−1 g−1, which is 51 times that of pure C3N4 under visible light conditions. The photocatalytic degradation performance of tetracycline and oxidation performance of benzene is also expressed, with a degradation rate of 100%, a conversion of 97.3% and a selectivity of 99.9%. This work focuses on the structure-activity relationship to provide the possibilities for the development of potential photocatalytic materials.
Interface engineering is of great importance to improve the photocatalytic performance. Herein, in-situ formation plasmon Bi/BiOCl nanosheets assembled heterojunction microspheres are fabricated via facile reductive solvothermal approach. The aldehyde group in the DMF structure is used to exert the weak reducing property of the solvent and thus strip out the metal Bi in BiOCl. The metal Bi is anchored on surface of BiOCl firmly due to in-situ formation engineered interface, which could realize efficient charge transfer channel. The resultant Bi/BiOCl heterojunctions assemblies with narrow bandgap of 3.05 eV and mesoporous structure extend the photoresponse to visible light region and could provide sufficient surface active sites. The visible-light-driven photocatalytic degradation of high-toxic norfloxacin for Bi/BiOCl heterojunctions is up to 95.5% within 20 min, representing several times that of pristine BiOCl nanosheets and the physical mixture. It is attributed to the in-situ formation of Bi/BiOCl heterojunctions and surface plasmon resonance (SPR) effect of plasmon Bi promoting charge transfer, and the obvious photothermal effect promoting the photocatalytic reaction, which are verified by experimental and density functional theory (DFT) calculations. This strategy provides ideal perspectives for fabricating metal/semiconductor heterojunctions photocatalysts with high-performance.
Owing to the large exciton binding energy (>100 meV) of most organic materials, the process of exciton dissociation into free electrons and holes is seriously hindered, which plays a key role in the photocatalytic system. In this study, a series of chalcogen (S, Se)-substituted mesoporous covalent organic frameworks (COFs) have been synthesized for enhanced photocatalytic organic transformations. Photoelectrochemical measurements indicate that the introduction of semi-metallic Se atom and the enlargement of conjugation degree can not only reduce the exciton binding energy accelerating the charge separation, but also reduce the band gap of COFs. As a result, the COF-NUST-36 with the lowest exciton binding energy (39.5 meV) shows the highest photocatalytic performance for selective oxidation of amines (up to 98% Conv. and 97.5% Sel.). This work provides a feasible method for designing COFs with high photocatalytic activity by adjusting exciton binding energy.
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