Latest ArticlesExploring highly efficient and non-noble-metal-based electrocatalysts for oxygen evolution reaction (OER) is of great importance not only for water splitting but also for rechargeable metal-air batteries and fuel cells. Herein, we describe a simple strategy to prepare hierarchical Ni@Mn-doped NiO hybrids using flower-like Ni-Mn layered double hydroxides (NiMn-LDHs) as a precursor. After calcination at 400 ℃ for an hour under N2 atmosphere, the flower-like NiMn-LDHs transform to porous microspheres consisting of nanoparticles, in which Ni cores are encapsulated by Mn-doped NiO shells (denoted as Ni@Mn-NiO-400). Benefiting to this unique porous, core-shell structures and element doping, the as-prepared Ni@Mn-NiO-400 hybrid shows a low overpotential of 178 mV at the current density of 10 mA/cm2 and Tafel slope of 52.7 mV/dec in 1 mol/L KOH solution. More significantly, the Ni@Mn-NiO-400 hybrid also demonstrates superior stability of 98.6% after 50 h continuously testing, much higher than pristine NiMn-LDHs and commercial IrO2 catalyst. In addition, theoretical simulation shows that Ni core and Mn doping greatly affect the electronic states and electronic structure of NiO. As a result, Ni@Mn-doped NiO hybrid possesses an optimal adsorption activity towards oxygen species than NiO and undoped Ni@NiO hybrid. Considering the compositional and structural flexibility of LDHs, this work may offer a simple method to prepare other non-noble metal-based electrocatalysts for OER.
Available online An efficient method for the synthesis of multi-substituted cyclic imides was developed with cyanoesters and diaryliodonium salts. This method proceeds through a cascade of N-arylation-acylation and rearrangement to give target heterocycles in good yields (up to 99%). This method has the major advantages of a broad substrate scope, excellent functional group compatibility. The strategy was also extended to the fused cyclic imides, such as malonimides, succinimides and glutarimides.
A stimuli-responsive supramolecular polymer network (G-(CN)2⊂BXDSP5) with aggregation-induced emission (AIE) properties has been efficiently constructed by host–guest interactions between pillar[5]arene derivative BXDSP5 and a homoditopic guest G-(CN)2, which shows not only excellent fluorescence properties due to the AIE effect but also desirable ion-sensing abilities in both solution and solid states, holding great potential in the applicable fluorescence detection for Fe3+. The resultant G-(CN)2⊂BXDSP5 can be transformed into supramolecular polymer gel at high concentration via multiple noncovalent interactions, showing multi-stimuli-responsiveness in response to temperature change, mechanical force, and competitive agent. Meanwhile, the xerogel of supramolecular polymer material has been successfully used to remove Fe3+ from water with high adsorption efficiency. In addition, an ion-responsive film based on supramolecular polymer has also been developed, which can serve as a practical and convenient fluorescence test kit for detecting Fe3+.
The oxygen reduction reaction (ORR), an important process in Zn-air batteries (ZABs), shows sluggish reaction kinetics, which significantly impairs the further improvement of battery performance. Thus, rationally designing cathodic catalysts for ZABs has drawn sufficient attention. We herein synthesize and characterize Fe/N/F-tridoped CNTs (FeNFCs) by annealing the postsynthesized trifluoroacetic anhydride-modified Fe-MIL-88B-NH2 nanocrystals with melamine at high temperature in a N2 atmosphere. Benefiting from the Fe/N/F element doping, high specific surface area, and CNT structure, the FeNFC800 catalyst prepared at 800 ℃ exhibits a preferable half-wave potential of 0.829 V vs. RHE. The Zn-air battery equipped with FeNFC800 shows a high open-circuit voltage of 1.47 V, a gratifying peak power density of 196 mW/cm2, and extraordinary long-term stability, outperforming the benchmark 20% Pt/C.
By developing gem–difluoromethylene allenes as viable partners, regiocontrolled Rh(Ⅲ)-catalyzed redox-neutral C–C coupling/C–N cyclization has been realized to build the pyridin-2(1H)-one motifs with the embedment of a Z-configured monofluoroalkene functionality, in which either (hetero)aromatic or vinylic amides were found to be compatible. Integrated experimental and computational mechanistic studies revealed that a tandem regioselective allene 1,2-insertion/β-H elimination/hydrogen transfer/oxidative addition/cyclization/cis-β-F elimination involving an unconventional Rh(Ⅲ)-Rh(Ⅰ)-Rh(Ⅲ) catalytic cycle accounts for the established transformation. Through further FMO analysis and IGMH maps, a non-covalent weak interaction network between the gem–difluoromethylene part and the OPiv moiety was rationally defined for the unconventional and specific regioselectivity control.
Protein self-labeling tags achieve selective fusion and labeling of target proteins through genetic coding technology, but require exogenous fluorescent probes with fluorogenicity for protein tag binding to have the performance of wash-free fluorescence imaging in live cells. In this paper, we reported a fluorogenic probe 1 capable of ratiometric fluorescence recognition of SNAP-tag proteins. In this probe, the O6-benzylguanine derivative of 3–hydroxy-1,8-naphthalimide underwent a selective covalent linkage reaction with SNAP-tag protein. The hydroxyl group on the naphthalimide fluorophore formed a hydrogen bond with the functional group near the protein cavity. The excited state proton transfer occurred after illumination, to obtain the ratio fluorescence signal from blue emission to red emission, realizing the wash-free fluorescence imaging of the target proteins.
The design of adhesive materials with strong adhesion capacity at low temperatures is a great challenge. Herein, we report a low-molecular-weight supramolecular adhesive that exhibits good adhesion performance to various surfaces at low temperatures (from −18 ℃ to −80 ℃). Moreover, this supramolecular adhesive has good adhesion ability in the presence of water.
Molybdenum disulfide (MoS2) has attracted great attention in hydrogen peroxide (H2O2) activation as a Fenton-like catalyst and cocatalyst, but the distinct mechanism of generating •OH remains unclear. In this paper, the metallic 1T phase and semiconducting 2H phase of MoS2 nanosheets were prepared and applied in MoS2/H2O2 and MoS2/Fe2+/H2O2 systems with and without light irradiation. Compared with 2H-MoS2, 1T-MoS2 exhibited superior removal rates in degrading organic pollutants in the two systems under light irradiation. However, the phase had little effect on activating H2O2 in the MoS2/H2O2 system under dark conditions. This is because it was difficult for the surface •OHads generated in the MoS2/H2O2 system to diffuse into solution, while the •OHfree radicals were mainly responsible for degrading organic pollutants. When introducing light irradiation, external energy may accelerate the desorption of •OHads into •OHfree. Interestingly, the conversion between Mo4+ and Mo5+ triggered the decomposition of H2O2 in the Fenton-like reaction, while the cycle of Mo4+/Mo6+ promoted the regeneration of Fe3+ when employing 1T-MoS2 as a cocatalyst. Meanwhile, the 1T-MoS2 catalysts exhibited excellent stability and ability to degrade various organics in the two systems. This work offers deeper insight into the MoS2-based Fenton-like and cocatalytic mechanisms.
A novel palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with phenols or arylboronic acids is described, which provides a facile approach to access indolo[2,1-a]isoquinoline scaffolds. This method employs benzene-1,3,5-triyl triformate (TFBen) as the CO surrogate for the incorporation of a carbonyl group into indolo[2,1-a]isoquinoline scaffolds, and a variety of carbonyl-containing indolo[2,1-a]isoquinoline derivatives are prepared in good yields.
Information-carrying capacity has become an important factor in the development of encryption and anti-counterfeiting. Herein, a hydrogen-bonded organic framework (HOF-PyTTA) was developed as novel anti-counterfeiting ink without rare metals and a smartphone-based APP was written for encryption and anti-counterfeiting. We found that the fluorescence of HOF-PyTTA can be quenched by Fe3+ ions and recovered by the addition of ascorbic acid. And the fluorescence of HOF-PyTTA can be enhanced by the increasing concentrations of ethanol. Based on these stimulus-response properties, four anti-counterfeiting models with gradually increased security were studied. Mode one was printed by HOFs ink and decrypted by UV light. Mode two was based on HOF-PyTTA and CsPbBr3 inks (or HOF-PyTTA-Fe3+) which are used to separately print the genuine and pirated information. A decryption reagent was applied to get the genuine information. Furthermore, we successfully construct a dynamic information encryption anti-counterfeiting model using a fluorescence array in combination with an information encryption anti-counterfeiting APP. The circular array is printed by several concentrations of HOF-PyTTA ink and different RGB thresholds are set with the help of the information encryption anti-counterfeiting APP, to obtain distinct encrypted anti-counterfeiting information, thus accomplishing a high information-carrying capacity.
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