Latest ArticlesPyrite-type sulfides (PTS) exhibit promising intrinsic activities for oxygen reduction and evolution reactions (ORR/OER). However, their poor electrical conductivities may limit the charge transfer rate to inevitably lower activity. Here, yolk-shell structured cobalt-pyrite nanospheres (CoS2 YSS) are prepared and modified with amino groups as nucleation sites for coupling highly-conductive needle-like nitrogen-doped carbon via a facile solvothermal method (CoS2 YSS@NC). The as-marked CoS2 YSS@NC-0.5 shows a gap between yolk and shell, and an obvious exterior layer of grafted NC, which can provide an integrated structure, an interior place, and three exposed surfaces on CoS2. CoS2 YSS@NC-0.5 reveals higher ORR activity (half-wave potential of 0.88 V) and methanol resistance than commercial Pt/C. Due to in-situ formation of highly-active CoOOH, CoS2 YSS@NC-0.5 shows a better overpotential (244 mV at 10 mA/cm2) and Tafel slope (135 mV/dec) than RuO2. Zinc-air battery with CoS2 YSS@NC-0.5 air-cathode exhibits good open circuit potential (1.44 V), specific capacity (772.5 mAh/g) and cycling stability. Needle-like NC layer coated on the yolk-shell structure of CoS2 effectively lowers the charge transfer resistance to obtain extraordinary ORR/OER activities. It indicates that the integration of highly-conductive carbon onto pyrite-type sulfides is an effective strategy to acquire durable bifunctional ORR/OER catalysts.
Herein, the degradation of florfenicol (FLO) over zero-valent iron (ZVI) enhanced by SiC was systematically investigated. It was found that 5 g/L of ZVI/SiC (1:3) at pH 3.0 could completely degrade 20 mg/L of FLO within 1 h, with a Kobs value of 0.0873 min−1, 12.5 times greater than that of pure ZVI (0.0069 min−1). Vibrating sample magnetometer (VSM) characterizations revealed that the use of SiC supporter reduces the magnetic intensity of ZVI, which mitigates iron particle agglomeration, increases Brunauer-Emmett-Teller (BET) surface area, and enhances FLO degradation efficiency. Furthermore, ZVI/SiC exhibits a much lower hydrogen evolution potential (HEP) and significantly higher corrosion currents compared to pure ZVI. FLO was proposed to undergo degradation via reductive dechlorination, involving a hydrogenolysis mechanism that entails the cleavage of the σ bond. This study provides new insights into the reduction hydrogenation mechanism of ZVI.
The kinetic of low-temperature carrier and lattice of lead-halide perovskite is yet to be fully understood. In this work, we investigate the steady-state photoluminescences (PLs) of CsPbI3 at the environmental temperature (Te) ranging from 20 K to 300 K, and observed anomalous behaviors at cryogenic temperatures: The carrier temperature (Tc) of pure CsPbI3 exhibits a negative correlation with Te, accompanied by an expansion in Urbach tails of absorption spectra (Abs.) and excessive red-shifts at peak energy of PLs. These phenomena are also observed in those samples containing a certain amount of Cs4PbI6, but to a lesser extent and occurs at lower temperatures. It is attributed to the intensified hot phonon bottleneck effect (HPB) in CsPbI3 at cryogenic Te, which hinders the energy transfer from hot carriers, via longitudinal optics (LO) phonons to longitudinal acoustic (LA) phonons, to the ambient. For samples under continuous-wave laser excitation, in specific, the barrier induced by the enhanced HPB at low Te prevents the effective thermalization among carriers, LO and LA phonons, which, therefore, form thermally isolated ensembles with different temperatures. At cryogenic Te range, the elevated temperatures of carrier and LO phonon expand the high-energy side of PLs and the low-energy tail of Abs., respectively. For those samples in which the CsPbI3 is mixed with Cs4PbI6, the interfacial LO-LO interaction across them provides a bypass for heat dissipation, mitigating the heat accumulation in LO-phonons of CsPbI3. The results suggest that a strong HPB effect may break the thermal equilibrium among different branches of phonons in the lattice under certain extreme conditions.
The photocatalytic conversion of biomass into high-value chemicals, coupled with simultaneous hydrogen (H2) evolution, leveraging the electrons and holes generated by solar energy, holds great promise for addressing energy demands. In this study, we constructed a dual functional photocatalytic system formed by NiS loaded on Ni doped two-dimensional (2D) CdS nanosheet (NiS/Ni-CdSNS) heterostructure for visible-light-driven H2 evolution and ethanol oxidation to acetaldehyde. Remarkably, the 2D NiS/Ni-CdSNS exhibited significant activity and selectivity in both photocatalytic H2 evolution and ethanol oxidation, achieving yields of 7.98 mmol g−1 h−1 for H2 and 7.33 mmol g−1 h−1 for acetaldehyde. The heterogeneous interface of the composite facilitated efficient charge separation, while NiS provided abundant sites for proton reduction, thereby promoting the overall dual-functional photocatalytic activity. Density functional theory calculations further reveal that both Ni doping and NiS loading can reduce the reaction energy barrier of ethanol oxidation of free radicals, and NiS/Ni-CdSNS composite materials exhibit stronger ethanol C-H activation ability to generate key intermediate •CH(OH)CH3 on the surface. This work serves as a valuable guide for the rational design of efficient dual functional photocatalytic systems that combine H2 evolution with the selective conversion of organic compounds into high-value chemicals.
Disgusting deposits (e.g., scale and crude oil) in daily life and industrial production are always serious problems, posing great threats to the safety and economic development. However, most of developed coatings can only conquer one part of these deposits such as superhydrophobic coatings possess anti-scaling capacity but would adhere crude oil. To integrate scale resistance with oil repellence, we herein report a robust superamphiphobic (SAB) coating simultaneously reducing pollution of scale and oil for extended period of time (two weeks with over 98% reduction). Compared with single role of superhydrophobic and amphiphilic surfaces, the SAB coating can not only inhibit interfacial nucleation of scale but also reduce the adhesion of formed scale and polluted oil. The durability of the SAB coating is evaluated via mechanical tests (sandpaper abrasion, tape stripping and sand falling) and chemical corrosion (corrosive liquid immersing), revealed by sustainable high contact angles and low contact angle hysteresis of water and oil. The universality of this strategy can be further confirmed by adding different particles like kaolin, Al2O3, and SiO2, resisting multiple types of scale (i.e., CaSO4, BaSO4 and MgCO3) and oil (i.e., glycerol, glycol, and mineral oil). Therefore, this study provides an ideal avenue for resisting scale and oil, which may be used for conquering the complexity of application environments (e.g., oil production and transportation).
The development of large-scale cell cultivation and non-invasive cell harvesting is highly desired in various fields, including biological regeneration and pharmaceutical research. When using traditional microcarriers for cell culture, trypsinization is often necessary during cell collection, leading to partial cells damage. In this work, we developed a thermoresponsive glass microcarrier modified with poly(γ-propargyl-ʟ-glutamate) (PPLG) and poly(N-isopropylacrylamide) (PNIPAM). We utilized these microcarriers for three-dimensional cell culture and enzyme-free cell harvesting, and the results indicated that the prepared microcarriers exhibited excellent non-invasive cell culture performance.
A highly efficient and concise bromocyclization has been successfully achieved, in which tryptamine/tryptophol derivates can be transformed to valuable HPI/TFI scaffolds with economic and green manners. Moreover, a controllable cascade transformation of bromocyclization and aromatic bromination has also been smoothly achieved to form dibrominated HPIs and TFIs. Production could be successfully scaled up under both the batch process and a continuous flow fashion. The most remarkable peculiarity of our process over all previous methods is that the generated water is the major waste. Notably, successful application of this new protocol has been demonstrated by the pharmaceutical and natural products syntheses.
Anode free lithium metal batteries (AF-LMBs) have conspicuous advantages both in energy density and the compatibility of battery manufacturing process. However, the limited cycle life of AF-LMBs is a crucial factor hindering its practical application. Fluorinated or nitride artificial inorganic solid electrolyte interphase (SEI) has been found as an effective method to prolong the lifespan of AF-LMBs. Herein, by investigating the impact of nano-sized inorganic gradient layers (LiF or Li3N) on initial Li deposition behavior, we notice that the Li+ diffusion barrier and the deposition morphology are highly depended on the thickness of inorganic layers. Thicker protective layers cause larger overpotential as well as more aggregated Li+ distribution. This study reveals that the ideal SEI should be synthesized thin and uniformly enough and uncontrollable artificial SEI can cause damage to the lifespan of AF-LMBs.
The external stimulus response strategy has been evolved rapidly in the field of olefin polymerization. In this work, we modularly synthesized three types of double stimulus responsive α-diimine palladium catalysts, combining redox regulation and other regulation together, such as light, Lewis acid and alkali cations. The catalytic activities and the molecular weight of polyethylene products can be regulated for 4 times in ethylene polymerization. These palladium complexes were also used for the copolymerization reaction of ethylene and polar monomers, such as methyl 10-undecylenate and methyl acrylate, effectively regulating the catalytic activities, the molecular weight and polar monomer incorporation of the prepared copolymers. The research on these dual-regulated palladium complexes makes full use of prepared catalysts and provides new inspirations for regulating olefin polymerization.
Fe-based Fenton agents can generate highly reactive and toxic hydroxyl radicals (·OH) in the tumor microenvironment (TME) for chemodynamic therapy (CDT) with high specificity. However, the low pH environment and insufficient endogenous hydrogen peroxide (H2O2) of the highly efficient Fenton reaction limits its practical application in clinic. Here, a Cu(Ⅱ)-doped mesoporous silica nanoagent (Cu-MSN) with excellent dispersity was successfully developed. After loaded with doxorubicin (DOX) and ascorbate (AA), Cu-MSN@DA was coated with active targeting ligand folic acid (FA), dimethyl maleic an-hydride (DMMA) and carboxymethyl chitosan (CMC) to obtain an active transporting nanoagent (FCDC@Cu-MSN@DA) with tunable charge-reversal property, which is more adaptable to the pH value of TME than Fe-based Fenton agents, and can self-supply exogenous H2O2 by ascorbate to produce more toxic ·OH to trigger the apoptosis of cancer cells. Meanwhile, the high level of glutathione (GSH) in TME can reduce Cu(Ⅱ) to Cu(Ⅰ) by Fenton-like reaction, increasing the generation rate of ·OH and relieving tumor antioxidant ability. The supply of exogenous H2O2 significantly enhanced the synergistic effect of CDT by oxidative damage. Together with DOX-induced cell apoptosis, this novel nanoagent FCDC@Cu-MSN@DA can achieve maximum therapeutic efficacy, creating a new model of safe and effective tumor treatment with high specificity.
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