We synthesized a series of carbon‐supported atomic metal‐N‐C catalysts (M‐SACs: M=Mn, Fe, Co, Ni, Cu) with similar structural and physicochemical properties to uncover their catalytic activity trends and mechanisms. The peroxymonosulfate (PMS) catalytic activity trends are Fe‐SAC>Co‐SAC>Mn‐SAC>Ni‐SAC>Cu‐SAC, and Fe‐SAC displays the best single‐site kinetic value (1.65×105 min−1 mol−1) compared to the other metal‐N‐C species. First‐principles calculations indicate that the most reasonable reaction pathway for 1O2 production is PMS→OH*→O*→1O2; M‐SACs that exhibit moderate and near‐average Gibbs free energies in each reaction step have a better catalytic activity, which is the key for the outstanding performance of Fe‐SACs. This study gives the atomic‐scale understanding of fundamental catalytic trends and mechanisms of PMS‐assisted reactive oxygen species production via M‐SACs, thus providing guidance for developing M‐SACs for catalytic organic pollutant degradation.

Pathogenic drug-resistant bacteria represent a threat to human health, for instance, the methicillin-resistant Staphylococcus aureus (MRSA). There is an ever-growing need to develop non-antibiotic strategies to fight bacteria without triggering drug resistance. Here, we design a hedgehog artificial macrophage with atomic-catalytic centers to combat MRSA by mimicking the “capture and killing” process of macrophages. The experimental studies and theoretical calculations reveal that the synthesized materials can efficiently capture and kill MRSA by the hedgehog topography and substantial generation of •O2− and HClO with its Fe2N6O catalytic centers. The synthesized artificial macrophage exhibits a low minimal inhibition concentration (8 μg/mL Fe-Art M with H2O2 (100 μM)) to combat MRSA and rapidly promote the healing of bacteria-infected wounds on rabbit skin. We suggest that the application of this hedgehog artificial macrophage with “capture and killing” capability and high ROS-catalytic activity will open up a promising pathway to develop antibacterial materials for bionic and non-antibiotic disinfection strategies.

The glass transition of poly(2,6-dimethyl-1,5-phenylene oxide) (PPO) films with thickness ranging from about 6 nm (approximately half of radius of gyration, R g ) to 330 nm (∼29 R g ) was studied by the recently developed differential alternating current chip calorimeter with sensitivity on the order of tenths of a pJ K -1 . No thickness dependence of the glass temperature T g was found for this polymer. T g s of all the films measured in the available frequency range (∼0.5 to ∼1000 Hz) can be fit by a single Vogel-Fulcher-Tammann function in the activation plot within an uncertainty of (3 K, thus showing no deviation from the common VFT behavior even for the thinnest film. There is also no detectable change in the shape or width of the step in heat capacity at T g . Finally, we found that calorimetric relaxation strength at the glass transition was proportional to the thickness of the film within an uncertainty of about 25%. Consequently, we estimate the thickness of the layer deviated from the bulky behavior to be within 1.5 nm.

Rheology experiments were performed to monitoring the kinetics of the entanglement recovery process of freeze-dried polystyrene. Complete reentanglement time requires unexpected long time, which does not monotonically reduce with the concentration of precursor solution. The entanglement recovery was treated as the complementary process of stress relaxation in Doi−Edwards model and was found to agree well with the exponential law. We clarified that freeze-drying is an effective way to achieve disentanglement for polymer chains. The correlation between recovery time and the concentration of precursor solution is in good agreement with previous results from molecular dynamics (MD) simulations.

The rheological properties of liquid polybutadiene rubber/organo-clay nanocomposite gels were investigated by rheological experiments, focusing on the effects of clay exfoliation and orientation−disorientation as well as polymer−clay interaction and temperature. Both irreversible and reversible viscosity transitions were observed in the temperature range from 26 to 136 °C in steady shear experiments on as-prepared and exfoliated samples. These transitions depend strongly on the end groups, molecular weight of the liquid rubber, and the shear field. The irreversible transition is attributed to the exfoliation of the clay, and the reversible transition can be understood as a shear-induced orientation−disorientation transition of the clay sheets. Polymer−clay interaction is confirmed to be a key controlling factor of the orientation−disorientation transition, whereas the shear field plays a critical role to induce such a transition. To our knowledge, this is the first rheological observation of the in-situ exfoliation process and the shear-induced orientation−disorientation transition of layered silicate in polymer/organo-clay nanocomposites. A tentative model was suggested on the basis of the clay exfoliation and orientation−disorientation transition, and the model is used to explain the observed unique rheological behavior.

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Developing low-cost electrocatalysts for efficient and robust oxygen evolution reaction (OER) is the key for scalable water electrolysis, for instance, NiFebased materials. Decorating NiFe catalysts with other transition metals offers a new path to boost their catalytic activities but often suffers from the low controllability of the electronic structures of the NiFe catalytic centers. Here, we report an interfacial atomsubstitution strategy to synthesize an electrocatalytic oxygen-evolving NiFeV nanofiber to boost the activity of NiFe centers. The electronic structure analyses suggest that the NiFeV nanofiber exhibits abundant high-valence Fe via a charge transfer from Fe to V. The NiFeV nanofiber supported on a carbon cloth shows a low overpotential of 181 mV at 10 mA cm À 2 , along with long-term stability (> 20 h) at 100 mA cm À 2 . The reported substitutional growth strategy offers an effective and new pathway for the design of efficient and durable non-noble metal-based OER catalysts.