Latest ArticlesExploring remarkable oxygen reduction reaction (ORR) electrocatalysts for regenerative fuel cells and metal-air batteries is highly essential. Herein, a novel non-noble metal-based heterogeneous electrocatalyst with rich defects were successfully synthesized by liquid-liquid interfacial precipitation (LLIP) of fullerene (C60) and ferrotetraphenylporphyrin (FeTPP) followed by one step pyrolysis. The obtained product annealed at 700 ℃ (C60/FeTPP-700), when employed as ORR electrocatalyst, revealed a positive half-wave potential (E1/2) of 0.877 V vs. reversible hydrogen electrode (RHE), which was superior to that of the commercial 25% Pt/C. Delightfully, the assembled Zn-air battery (ZAB) using C60/FeTPP-700 as an air-electrode catalyst exhibited a high power density of 153 mW/cm2, specific capacity of 668 mAh/g and long-term cycling stability for more than 250 h. Experimental results proved that the excellent electrocatalytic ORR activity of C60/FeTPP-700 would attribute to the synergistic effect between FeNx sites, Fe3C/Fe nanoparticles and the structure defects. This work provides a feasible and simple method to prepare non-noble metal-based ORR electrocatalysts for the application of energy storage and conversion.
Stable solid-electrolyte interphase (SEI) is crucial for advanced development of lithium metal batteries. However, the continuous collapse and reconstruction of SEI will deplete fresh Li and electrolytes upon cycling, leading to irreversible capacity loss. Herein, we addressed this issue by pre-formation of artificial robust hybrid interphase on a 3D layered graphene/lithium metal framework, in which is constructed by LiF associated with Li2TiF6 generated by the in-situ reaction between the surfacial lithium and titanium fluoride contained electrolytes. The as-obtained interphase can maintain the structure integrality and avoid continuous consumption of the fresh Li and electrolytes. As a consequence, the Li symmetric cells achieve high-efficiency Li deposition and stable cycling over 3600 h. When paired with LiFePO4 cathodes, the coin cells exhibit long lifespan (> 800 cycles) with almost 88.3% retention of the initial capacity.
Ultra-low dielectric loss (Df) and low dielectric constant (Dk) materials are urgently required in high-speed and large-capacity transmission, in which the wholly aromatic liquid crystal polymer (LCP) has gained attention due to its excellent dielectric properties. However, the relationship between molecular structure and dielectric properties is still not clear. In this study, two copolyesters containing phenyl or naphthyl structures are synthesized, as well as the effects of benzene and naphthalene mesogens on dielectric properties are investigated. The synthesized copolyesters containing naphthalene structure have good comprehensive properties with high thermal stability (T5% = 479 ℃ and Tg = 195–216 ℃), inherent flame retardance (LOI = 33.0–35.0 and UL-94 V-0 level at 0.8 mm), low Dk (2.9–3.0@10 GHz) and low Df (0.0027–0.0047@10 GHz). Naphthalene mesogen can reduce the dielectric loss more significantly than benzene at high frequency by reducing the density and mobility of polarizable groups, which leads to the effectively limited dipole polarization in copolyesters. Consequently, we proposed a new strategy for designing low Dk and low Df materials.
In order to balance the conductivity and flexural strength of graphite composite bipolar plates, the influence of conductive filler on the properties of graphite composite bipolar plate was comprehensively studied by using phenolic resin as binder, natural flake graphite as conductive substrate and functional carbon materials with different structures as auxiliary filler. The results show that the particle size of conductive substrate has an important influence on the conductivity enhancement of auxiliary filler. The influence of conductive particle size on auxiliary filler electrical conductivity improvement was first investigated in this research. The effects of various auxiliary filler concentrations on improving electrical conductivity and flexural strength were then examined. This research has substantial implications for the balance of electrical conductivity and flexural strength of graphite composite bipolar plates.
Obesity, characterized by the dysregulation of energy balance in adipose tissue and other metabolic organs, is frequently accompanied by chronic low-grade inflammation. As long-acting insulin sensitizers, the organically-derivatized polyoxovanadates (POVs), can extend the dosing interval of antidiabetic drugs from hourly to almost daily. In this work, the protective activity of POVs is investigated by an eight-week in vivo experiment, in which a small amount of POVs was administrated orally to a mouse model of diet-induced obesity every day. The present study shows that administration of POVs significantly decreases the body weight of mice, reduces adipose tissue accumulation, and simultaneously reduces adipose tissue inflammation. In addition, the anti-obesogenic population of iNKT cells is protected potentially by POVs, which subsequently alleviates visceral adipose tissue inflammation in high-fat-diet (HFD)-fed mice against diet-induced obesity. By contrast, the change in body weight after POV treatment is the result of a substantial reduction in fat mass, with no obvious effects on lean body mass. These findings demonstrate that supplementary of POVs would be an effective way to combat obesity and metabolic disorders while lowering metabolic inflammation.
Cisplatin is broad-spectrum chemotherapeutic agent that has been widely used for the treatment of a variety of malignant tumors including breast cancer. However, the cisplatin chemoresistance, which derives from the inactivation by glutathione (GSH) depletion, remains a scientific issue to solve. Here, we report a novel type of smart disulfide switchable nanoparticles complexing cisplatin (switch NPs-cisplatin) that is rationally designed, and engineered by synthesizing a hyaluronic acid disulfide bonded polyaspartic acid (HA-ss-Pasp) and complexing cisplatin. The results showed that the switch NPs-cisplatin had a nanoscale of particle size (150 nm), higher drug encapsulation efficiency (> 90%), and suitable drug release profile. They demonstrated evident pH responsiveness and GSH responsiveness, and targeting effect in the resistant breast cancer cells. Furthermore, they were able to block the cisplatin depletion by GSH in the resistant cancer cells, thereby circumventing the chemoresistance. Consequently, switch NPs-cisplatin displayed a remarkable killing effect in the resistant breast cancer cells in vitro, and in the resistant breast cancer-bearing mice. In conclusion, switch NPs-cisplatin could be used as a smart formulation of cisplatin for overcoming the chemoresistance of breast cancer. The present study also offers a universal drug delivery carrier platform for highly efficient but low systemic toxic chemotherapy.
High residual concentration of arsenic and fluoride is a tricky problem to be solved in the process of reinjection after geothermal water utilization. We develop a method to simultaneously remove As(Ⅴ) and F− from geothermal water using magnetic Fe3O4@MgO adsorbent, fabricated via a one-step method. The effects of pH, contact time, adsorbent dose and temperature on the removal efficiency were investigated systematically. The results show that the Fe3O4@MgO composite has a wide range of pH (2–11), ultrafast removal dynamics (As(Ⅴ): 2 min; F−: 30 min), and high removal efficiency (As(Ⅴ): 99.9%; F−: 96.6%). The adsorption kinetics follows the pseudo-second-order kinetics model, and the adsorption isotherm model fits Freundlich. The adsorption capacity of As(Ⅴ) and F− can reach 123 and 98.4 mg/g, respectively. The exchange of As(Ⅴ) and F− with Mg-hydroxyl groups hydrolysis by MgO was determined the adsorption mechanism. The Fe3O4@MgO adsorbent was capable of achieving the adsorption efficiency as high as 99.9% for As(Ⅴ) and 97.3% for F− in real geothermal water, respectively. Hence, the proposed Fe3O4@MgO composite exhibited as an excellent adsorbent for the remediation of As- and F-contaminated geothermal water.
Deep eutectic solvents (DESs) have drawn considerable attention as a new type of green solvent since they were reported. Subsequent studies have shown that DESs have the potential to be used as "designable" solvents, which means that the precursors of DESs with different structures and properties can be screened to customize DESs for specific functions. Researchers have found that during the sample preparation process involving DESs, the specific properties of some "smart" DESs can be switched by directing external driving forces, leading to a reversible phase transition of the target solution. These "smart" DESs are called switchable deep eutectic solvents (SDESs). The advent of SDES simplifies the sample pretreatment steps, reduces the use of organic solvents, and makes solvents easy to recycle, which matches the concept of green and sustainable chemistry. Compared with the number of previous experimental studies, the reviews and summaries on SDESs are rare. Therefore, this review made a summary of the concept and research progress of SDESs based on some related works in the past decade, including composition and type, characterization, switching mechanism, etc. It is expected to provide a certain reference and guidance for the subsequent in-depth research of SDESs in the analytical sample pretreatment.
Owing to its outstanding photoactivity, ferrioxalate is originally used as an actinometer and subsequent work has discovered that photochemistry of ferrioxalate is also fundamentally or technically important in atmospheric chemistry and water treatment. While the overall products generated from photolysis of ferrioxalate are known to include Fe(Ⅱ), a series of oxidizing (e.g., •OH, O2•−/HO2•−) or reducing (C2O4•−/CO2•−) radicals and H2O2, however, at the molecular level, the primary step of the photoreaction of ferrioxalate remains as an unsolved mystery due to the difficulty in examining such ultrafast processes. Benefiting from the development of time-resolved spectroscopy, this old question has been studied with increasing vigor recently, by means of such ever-more-sophisticated techniques (e.g., flash photolysis, time-resolved X-ray absorption spectroscopy (XAS), femtosecond infrared (IR) absorption spectroscopy, ultrafast photoelectron spectroscopy (PES)). There are two contrary views on the primary reaction mechanism: (1) Intramolecular electron transfer (ET) precedes the cleavage of the metal-ligand bond; (2) The dissociation of C–C or Fe–O bond occurs before intramolecular ET. Thus, this review presents a comprehensive summary about the overall reaction mechanism and molecular level mechanism of ferrioxalates. In chronological order, we have elaborated two predominant but controversial views from the perspectives of different experimental approaches. Some challenges and research opportunities in this active field are also briefly discussed.
The integrated lipopeptide (RVA)/gene complexes are fabricated with bi-directional regulation on tumor cells and micro-environment. After self-assembling and target coating modification, the poly(γ-glutamic acid) (γ-PGA)/RVA nano-vectors can sequentially respond to pH & redox stimuli, and guarantee efficient therapeutic gene delivery and control release of all-trans retinoic acid. The design provides a facile but promising strategy to treat refractory cancers.
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