Latest ArticlesThe high specific capacity and low negative electrochemical potential of lithium metal anodes (LMAs), may allow the energy density threshold of Li metal batteries (LMBs) to be pushed higher. However, the existing detrimental issues, such as dendritic growth and volume expansion, have hindered the practical implementation of LMBs. Introducing three-dimensional frameworks (e.g., copper and nickel foam), have been regarded as one of the fundamental strategies to reduce the local current density, aiming to extend the Sand' time. Nevertheless, the local environment far from the skeleton is almost the same as the typical plane Li, due to macroporous space of metal foam. Herein, we built a double-layered 3D current collector of Li alloy anchored on the metal foam, with micropores interconnected macropores, via a viable thermal infiltration and cooling strategy. Due to the excellent electronic and ionic conductivity coupled with favorable lithiophilicity, the Li alloy can effectively reduce the nucleation barrier and enhance the Li+ transportation rate, while the metal foam can role as the primary promotor to enlarge the surface area and buffer the dimensional variation. Synergistically, the Li composite anode with hierarchical structure of primary and secondary scaffolds realized the even deposition behavior and minimum volume expansion, outputting preeminent prolonged cycling performances under high rate.
The application of photothermal therapy (PTT) is greatly limited by the low accumulation of photothermal agents, uneven photothermal distribution, and heat endurance of cancer cells. Worse still, despite PTT enhances immunogenicity, the anti-tumor immune efficacy is still unsatisfactory due to the inefficient immunogenic cell death (ICD) induction and poor infiltration of immune cells. To solve the above problems of PTT, we developed hyaluronic acid (HA) modified hollow copper sulfide nanoparticles encapsulating diethyldithiocarbamate (DDTC) to construct a breast tumor targeting and near infrared (NIR) photo-responsive drug delivery system (D-HCuS@HA), which further combined with losartan to improve the accumulation and penetration in the tumor site. Upon irradiation, D-HCuS@HA realized enhanced PTT and released cytotoxic Cu(DDTC)2 to eliminate heat endurance tumor cells, thereby enhancing anti-tumor effect and inducing effective ICD. Moreover, the combination with losartan could remodel the tumor microenvironment, allowing more T cells to infiltrate into the tumor, and significantly inhibiting the occurrence and development of metastatic tumors. In vitro/vivo results revealed the great potential of D-HCuS@HA combined with losartan, which provides a new paradigm for anti-tumor and anti-metastases.
It is well-established that high carbonization temperature will trigger the enzyme-like activity of carbon-based materials. However, the catalytic mechanism is still ambiguous, which hinders the further rational design of nanomaterials as enzyme mimics. Hereby, N, S-rich carbonized wool nanosheets (CWs) were synthesized at different pyrolysis temperatures. As expected, only CWs treated with high-temperature possess intrinsic oxidase- and peroxidase-like activities. Meanwhile, density functional theory (DFT) calculations demonstrate that graphitic nitrogen and the co-existence of nitrogen and sulfur in the carbon matrix serve as the active sites for the enzyme-like process. More importantly, combining theoretical calculations and experimental observations, the high-temperature triggered catalytic mechanism can be ascribed to the fact that an appropriate high-temperature maximizes the graphitization degree to a certain extent, at which most of the catalytic active sites are well retained rather than evaporating. Moreover, coupling with excellent photothermal conversion efficiency and catalytic performance, CWs can be applied to photothermal-catalytic cancer therapy under near-infrared region (NIR) light irradiation. We believe this work will contribute to understanding the catalytic mechanism of carbon-based nanozymes and promote the development of new biomedical and pharmaceutical applications.
Molecular structure of organic semiconductor plays a critical role in determining the performance and functionality of organic electronic devices, by optimizing the electrical, optical and physicochemical properties. Substituted alkyl chains are fundamental units in tailering the solubility and assemblability, among which the asymmetric properties have been reported as key element for controlling the packing motifs and intrinsic charge transport. Here, we expanded the scope of molecular asymmetry dependent sensing features based on a new series of naphthalene diimides (NDI)-based derivatives substituted with a same branching alkyl chain but various linear-shaped alkyl chains (Cn-). A clear molecular stacking change, from head-to-head bilayer to head-to-tail monolayer packing model, is observed based on the features of anisotropic molecular interactions with the change in the chain length. Most importantly, a unique LUMO level shift of 0.17 eV is validated for NDI-PhC4, providing a record sensitivity up to 150% to 0.01 ppb ammonia, due to the desired molecular reactivity and device amplification properties. These results indicate that asymmetric side-chain engineering opens a route for breath healthcare.
Silyl cobalt species are putative intermediates in cobalt-catalyzed transformations of hydrosilanes. However, their reactivity has remained poorly understood. Reported here is the investigation on four-coordinate disilyl Co(Ⅱ) complexes with N-hetereocyclic carbene ligation. The reactions of [(ICy)2Co(vtms)] (ICy = 1, 3-dicyclohexylimidazol-2-ylidene, vtms = vinyltrimethylsilane) with primary and secondary hydrosilanes (3 equiv.) furnish the four-coordinate disilyl complexes [trans-(ICy)2Co(SiHRRʹ)2] (SiHRRʹ = SiH2Mes, 1; SiH2Ph, 2; SiH2Cy, 3; SiHPh2, 4; SiHEt2, 5) in moderate to good yields. The structures of 1, 2 and 4 were established by single-crystal X-ray diffraction. Solution magnetic susceptibility measurement and EPR spectroscopy indicate their low-spin nature (S = 1/2). Reactivity studies on 4 led to the establishment of the conversions of 4 to the disilyl dihydride Co(Ⅲ) complex [K(THF)][(ICy)2Co(H)2(SiHPh2)2]n (6) and the fluorosilyl Co(Ⅱ) complex [(ICy)2Co(THF)(SiFPh2)][BF4] (7) when 4 was treated with excess amount of K and AgBF4, respectively, in THF. These conversions hint at the high activity of low-valent and high-valent disilyl cobalt species [trans-(ICy)2Co(SiHPh2)2]1− and [trans-(ICy)2Co(SiHPh2)2]2+. Complex 4 is reactive toward terminal alkynes, but inert toward alkenes and internal alkynes. The reactions of 4 with terminal alkynes CyCCH and Me3SiCCH (3 equiv.) yield the Co(Ⅱ) complexes [(ICy)2Co(CCCy)2] (8) and [(ICy)2Co(CCSiMe3)((SiMe3)CCH2)] (9), respectively, along with H2SiPh2 and alkynylsilanes RCCSiHPh2 (R = Cy, SiMe3), whereas the reaction with 4-CF3C6H4CCH (3 equiv.) produce [(ICy)2Co(CCAr)((Ar)CCH(SiHPh2)CCHAr)] (Ar = 4-CF3C6H4) (10) and H2SiPh2. These reactions are proposed to involve σ-bond metathesis reactions between alkyne C(sp)-H bonds and Co-Si bonds in 4. Complexes 6–10 have been characterized by NMR spectroscopy, X-ray diffraction study, and elemental analysis.
Electrochemical oxidation is an effective method to degrade persistent organic pollutants. However, due to the limited catalytic activity of traditional thin film electrodes, the anodic oxidation process is slow and usually requires high energy consumption. Herein, Ti/SnO2-Sb electrode with regulated surface structure was reported to enhance the performance for electrochemical oxidation of persistent organic pollutants. The electrode deposited with SnO2-Sb nanoneedles (Ti/N-SnO2-Sb) showed higher oxidation activity. Its kinetic constant for perfluorooctanoic acid (PFOA) oxidation was 2.0 h−1 and the total organic carbon removal rate was 81.7% (4 h) at a relatively low current density of 6 mA/cm2. Compared with Ti/SnO2-Sb thin film and nanoparticles, Ti/N-SnO2-Sb significantly improved the electrochemical active area and •OH yield, and simultaneously reduced the electron transfer resistance, which enabled it to oxidize PFOA more rapidly even at a lower potential. This work provides a new strategy for promoting the electrochemical oxidation performance.
Luminescent materials that can be reversibly switched by electric field stimulation are attractive since the potential application for optoelectronic devices. Here we report a triplet-triplet annihilation upconversion (TTA-UC) system with electrophoretic response which is developed as the electrophoretic ink. The TTA-UC system consists of an ionic derivative of 9, 10-diphenyl anthracene (DPA) as the annihilator and Pt(Ⅱ) octaethylporphyrin (PtOEP) as the sensitizer. Upon applying an electric field, migration and enrichment of positively charged DPA derivatives towards the cathode results in a 20% enhancement of TTA-UC. A quasi-solid film for electrically writing is made using the electrophoretic TTA system as the ink and a platinum electrode as a pen. The prototype of TTA-UC ink demonstrates unique luminescence functions upon electrically writing and erasing, providing a promising strategy to develop electronic devices for display, information storage and encryption.
Vanadium flow batteries (VFBs) have drawn considerable attention as an emerging technology for large-scale energy storage systems (ESSs). One of the pivotal challenges is the availability of eligible ion exchange membranes (ICMs) that provide high ion selectivity, proton conductivity, and stability under rigorous condition. Herein, a 'side-chain-type' strategy has been employed to fabricate highly stable phenolphthalein-based cardo poly(arylene ether ketone)s (PAEKs) membrane with low area resistance (0.058 Ω cm2), in which flexible alkyl spacers effectively alleviated inductive withdrawing effect from terminal ion exchange groups thus enabling a stable backbone. The assembled VFBs based on PAEKs bearing pendent alkyl chain terminated with quaternary ammonium (Q-PPhEK) demonstrated an energy efficiency above 80% over 700 cycles at 160 mA/cm2. Such a remarkable results revealed that the side-chain-type strategy contributed to enhancing the ICMs stability in strong oxidizing environment, meanwhile, more interesting backbones would be woken with this design engaging in stable ICMs for VFBs.
A new continuous-flow process for the enzymatic synthesis of optically pure γ-lactones, which are used as flavors and fragrances in the food and cosmetic industries, was developed in a three-dimensional microfluidic reactor. The microchannels (175 mm in length, 0.9 mm in depth, and 1.72 mL in volume) were carved precisely inside a single borosilicate glass (90 mm × 75 mm × 12 mm) with ultrafast femtosecond laser micromachining. The flow field analysis and reaction simulation showed that the mixing of substrates and enzymes was enhanced, allowing the adjustment of residence time in a wide window. SmCRV4, a carbonyl reductase with excellent catalytic activity and enantioselectivity toward γ/δ-keto acids, was employed for the asymmetric synthesis of various chiral lactones. 30 mmol/L (R)-γ-decalactone (3g) can be obtained in 26 s with a space-time yield (STY) up to 16,877 g L−1 d−1, which is 14.4 times higher than the highest STY of batch reaction reported previously. This continuous-flow process was applied to the synthesis of 6 chiral lactones. In addition, the scaled-up synthesis of 3g was carried out in 6 cascade microreactors continuously for 6 h, demonstrating the feasibility and stability of the 3D continuous-flow process in enzymatic synthesis of optically pure compounds.
The innovation in polymer design to rival conventional polyethylene glycol (PEG) is an important approach to achieving a more sustainable society. Here, cyclic PEG-like polycarbonates having high molecular weight (4.4–49.5 kg/mol) were enabled through zwitterionic ring-opening polymerization (ZROP) of macrocyclic carbonates (MCs) mediated by N-heterocyclic carbene (NHC). The thermodynamic behavior of polymerization depends on the ring size of monomers. During this process, the ZROP of 11-membered MC was driven by the change of enthalpy (ΔHp) which differed from the ZROP of 14-membered MC driven by the entropic change (ΔSp). Cyclic polycarbonates depicted improved thermostability (Td5% ≥ 204 ℃) and higher glass transition temperatures (Tg > ‒40 ℃) in comparison to their linear analogues (Td5% ≤ 185 ℃, Tg ~‒50 ℃). In addition, the mechanism of ZROP of MC was addressed through computational study. A distinct mechanism of polymerization distinguishable from the well-known NHC-mediated ZROP of cyclic esters was revealed, where the zwitterion from nucleophilic addition to MC, i.e. tetrahedral intermediate, cannot be ring-opened probably due to the delocalization of negative charge on the carbonate group, but serves as an active center for the polymerization. In comparison to PEG, the attained polymer demonstrated comparable hydrophilic and biocompatible properties, as revealed by the results of contact angle and in vitro cytotoxicity studies, suggesting that cyclic polycarbonate hold the promise as the alternative of PEG.
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