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.
Metal-organic frameworks (MOFs) combined with specific ligands are highly adaptable smart materials that can respond to external and physiological stimuli. In this study, we introduced a pyridinyl zwitterionic ligand with light/pH dual response into magnetic MOF composite (Fe3O4@ZW-MOF) for enrichment of phosphorylated peptides for the first time. The introduction of the developed ligand gives MOF material dual response properties. Light stimulation affects the generation/disappearance of free radicals of the pyridine derivative, resulting in a change in the charge gradient of the zwitterion, and zwitterion can also regulate the pH of the solution by adding acid or base. Therefore, the reversible capture and release of phosphorylated peptides can be easily achieved by adjusting light and pH. The established phosphorylated peptide enrichment platform exhibits high sensitivity (detection limit of 1 fmol), high selectivity (β-casein: BSA, 1:1000), and good reusability (7 cycles). In addition, the method was applied to the enrichment of phosphorylated peptides in complex systems (non-fat milk and human serum), demonstrating the feasibility of this method for phosphoproteom analysis. In conclusion, the synthesized Fe3O4@ZW-MOF is a promising MOF material, which provides the possibility to advance the application of responsive MOFs materials in proteomics.
Utilizing CO2 for the production of bulky and valuable chemicals presents an attractive solution to address environmental and fossil energy crises. Among the various approaches, direct carboxylation of alcohols with CO2 stands out as an eco-friendly process capable of efficiently producing carboxylic acids in a sustainable manner. However, the high dissociation energy of the C-O bond poses a significant challenge in this process. Over the past few decades, several strategies have been developed to activate alcohols and establish efficient catalytic systems for carboxylation with CO2. Nevertheless, the sporadic nature of reported approaches makes it difficult to determine the most effective one. This perspective aims to provide an overview of the current state-of-the-art catalytic protocols for carboxylating alcohols with CO2, encompassing esterification, halogenation, and photocatalysis, while considering their respective advantages and limitations. We aim to discern the most promising avenues for future development in this field. The insights presented in this perspective will contribute to the advancement of efficient and sustainable carboxylation methods using CO2, leading to the production of valuable chemicals in future.
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.
Cobalt-based phosphides show excellent hydrogen evolution reaction (HER) performance, however, improving the intrinsic activity and stability of it in alkaline electrolyte still remains a challenge. Herein, CoRuOH/Co2P/CF with heterojunction structure was developed by means of molten salt and rapid hydrolysis (30 s). The OH− from rapid surface hydrolysis of Co2P as a hydrogen adsorption site can facilitate the formation of thin CoRuOH layer as a water dissociation site, which may bring out better synergistic effect for alkaline HER. Moreover, the covering of CoRuOH can improve the stability of Co2P for HER. When drives at 100 mA/cm2, it only requires overpotential of 81 mV in 1.0 mol/L KOH (25 ℃). Even at higher current density (1000 mA/cm2), CoRuOH/Co2P/CF can also operate stability for at least 100 h. When coupling with NiFe-LDH/IF in a two-electrode system, the voltage of NiFe-LDH/IF(+) || CoRuOH/Co2P/CF(−) at 1000 mA/cm2 is merely 1.77 V with 100 h, demonstrating great potential for water splitting. The implementation of this work provides a new strategy and reference for the further improvement of transition metal phosphides as HER electrocatalysts.
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.
Herein, we report the migratory hydroarylation of unactivated alkenes with aryl iodides using native and weakly coordinating amide directors under mild conditions. Synergistic coordination of the monodentate directing group and the ligand enable the highly regioselective migratory hydroarylation via a chain walking process to form the thermodynamically stable five-membered nickelacyle intermediate. The protocol provides a variety of valuable α-aryl-substituted alkylamine products, and exhibited good functional group tolerance. The modification of bioactive compounds such as fenofibrate and indomethacin further highlights the synthetic value of this protocol.
A nonsymmetrical PNN pincer ligand [6-(Bu2PNH)C5H4N-2-(3-Mes)C3H2N2] and its corresponding cobalt-N2 complex were synthesized and characterized. By the stoichiometric reaction of the PNN ligand lithium salt with CoCl2, the complex 3, (PNN)CoCl, was obtained. Then, reduction of 3 with NaBHEt3 under a dinitrogen atmosphere yielded complex 5, (PNN)Co(Ⅰ)(η1-N2). Single-crystal X-ray analysis, IR spectrum, and DFT calculations revealed that the dinitrogen in 5 was only weakly reduced by the cobalt center. The reactions of 5 with carbon monoxide and 2, 6-dimethylphenyl isocyanide gave carbonyl and isocyanide complexes 6 and 7 with the release of N2, respectively. Furthermore, these cobalt complexes, especially complex 5, demonstrated the capacity to convert dinitrogen to N(TMS)3 with moderate efficiency.
TiO2-based films are one of the most attractive photocatalysts owing to their highly cost-effective properties. Nevertheless, most TiO2-based photocatalytic films for dye degradation are in the form of robust films (without flexibility), TiO2 coatings on carbon matrix (with leakage risk), or surface-covered TiO2 hybrids (not favorite to contact with external molecules). Therefore, the development of durable and highly efficient TiO2 photocatalytic films for dye degradation is still needed. Here, we fabricated soft photocatalytic hybrid membranes (TANFs) from TiO2 nanotubes (TiNT) and aramid nanofiber (ANF) by a facile vacuum filtration process. The similar morphology and dimension of TiNT and ANF enable them intricately intertwine with each other in the membrane network. Under an appropriate mixing ratio, the TANF exhibited significantly improved optical and mechanical properties. When used for dye degradation, the membrane showed excellent photocatalytic performance and could keep stable activity and integrated state for repeated usage.
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