Integrating nitrogen species into sp 2-hybridized carbon materials has proved an efficient means to improve their electrochemical performance. Nevertheless, an inevitable mixture of nitrogen species in carbon materials, due to the uncontrolled conversion among different nitrogen configurations involved in synthesizing nitrogen-doped carbon materials, largely retards the precise identification of electrochemically active nitrogen configurations for specific reactions. Here, we report the preparation of single pyrrolic N-doped carbon materials (SPNCMs) with a tunable nitrogen content from 0 to 4.22 at.% based on a strategy of low-temperature dehalogenation-induced and subsequent alkaline-activated pyrolysis of 3-halogenated phenol-3-aminophenol-formaldehyde (X-APF) co-condensed resins. Additionally, considering that the pseudocapacitance of SPNCMs is positively dependent on the pyrrolic nitrogen content, it could be inferred that pyrrolic nitrogen species are highly active pseudocapacitive sites for nitrogen-doped carbon materials. This work gives an ideal model for understanding the contribution of pyrrolic nitrogen species in N-doped carbon materials.

UV-triggered self-healing of single microcapsules has been a good candidate to enhance the life of polymer-based aerospace coatings because of its rapid healing process and healing chemistry based on an accurate stoichiometric ratio. However, free radical photoinitiators used in single microcapsules commonly suffer from possible deactivation due to the presence of oxygen in the space environment. Moreover, entrapment of polymeric microcapsules into coatings often involves elevated temperature or a strong solvent, probably leading to swelling or degradation of polymer shell, and ultimately the loss of active healing species into the host matrix. We herein describe the first single robust SiO2 microcapsule self-healing system based on UV-triggered cationic polymerization for potential application in aerospace coatings. On the basis of the similarity of solubility parameters of the active healing species and the SiO2 precursor, the epoxy resin and cationic photoinitiator are successfully encapsulated into a single SiO2 microcapsule via a combined interfacial/in situ polymerization. The single SiO2 microcapsule shows solvent resistance and thermal stability, especially a strong resistance for thermal cycling in a simulated space environment. In addition, the up to 89% curing efficiency of the epoxy resin in 30 min, and the obvious filling of scratches in the epoxy matrix demonstrate the excellent UV-induced healing performance of SiO2 microcapsules, attributed to a high load of healing species within the capsule (up to 87 wt %) and healing chemistry based on an accurate stoichiometric ratio of the photoinitiator and epoxy resin at 9/100. More importantly, healing chemistry based on a UV-triggered cationic polymerization mechanism is not sensitive to oxygen, extremely facilitating future embedment of this single SiO2 microcapsule in spacecraft coatings to achieve self-healing in a space environment with abundant UV radiation and oxygen.

Substitutional doping of layered transition metal dichalcogenides (TMDs) has been proved to be an effective route to alter their intrinsic properties and achieve tunable bandgap, electrical conductivity and magnetism, thus greatly broadening their applications. However, achieving valid substitutional doping of TMDs remains a great challenge to date. Herein, a distinctive molten‐salt‐assisted chemical vapor deposition (MACVD) method is developed to match the volatilization of the dopants perfectly with the growth process of monolayer MoS 2 , realizing the substitutional doping of transition metal Fe, Co, and Mn. This doping strategy effectively alters the electronic structure and phononic properties of the pristine MoS 2 . In addition, a temperature‐dependent Raman spectrum is employed to explore the effect of dopants on the lattice dynamics and first‐order temperature coefficient of monolayer MoS 2 , and this doping effect is illustrated in depth combined with the theoretical calculation. This work provides an intriguing and powerful doping strategy for TMDs through employing molten salt in the CVD system, paving the way for exploring new properties of 2D TMDs and extending their applications into spintronics, catalytic chemistry and photoelectric devices.

netic layered transition-metal oxyhalides in a low-symmetry orthorhombic structure provide a new degree of freedom to modulate magnetism, [3] increasing the attention to explore their low-dimensional properties. [4][5][6] Recently, magnetic superstructures and optical anisotropies have been explored in layered single-crystal CrOCl. [4] Additionally, the atomic structure, work function, and magnetism of VOCl have been investigated. [5] Interestingly, relatively high Néel temperatures in monolayer FeOX (X = F, Cl, Br, or I) have recently been predicted by theoretical calculations, indicating that they are robust antiferromagnets. [7] Bulk FeOCl was first synthesized by Goldsztaub in 1935 [8] and it was reported to have the highest Néel temperature of 92 K among transition-metal oxyhalides. [4,5,9,10] It has been widely studied, specifically for its structure, [8,11,12] intercalation, [13][14][15][16][17] magnetism, [6,9,12,18] phase transition, [18,19] and catalytic performance. [20][21][22][23] Over the past decade, various methods, including chemical vapor transport (CVT), [8,[11][12][13][14][15][16][17][18][19][20][21][24][25][26] chemical vapor deposition, [27] partial pyrolysis, [22,23,28] liquid exfoliation, [29] chemical exfoliation, [6] and rapid thermal annealing, have been developed to 2D van der Waals (vdW) transition-metal oxyhalides with low symmetry, novel magnetism, and good stability provide a versatile platform for conducting fundamental research and developing spintronics. Antiferromagnetic FeOCl has attracted significant interest owing to its unique semiconductor properties and relatively high Néel temperature. Herein, good-quality centimeter-scale FeOCl single crystals are controllably synthesized using the universal temperatureoscillation chemical vapor transport (TO-CVT) method. The crystal structure, bandgap, and anisotropic behavior of the 2D FeOCl are explored in detail. The absorption spectrum and electrical measurements reveal that 2D FeOCl is a semiconductor with an optical bandgap of ≈2.1 eV and a resistivity of ≈10 −1 Ω m at 295 K, and the bandgap increases with decreasing thickness. Strong in-plane optical and electrical anisotropies are observed in 2D FeOCl flakes, and the maximum resistance anisotropic ratio reaches 2.66 at 295 K. Additionally, the lattice vibration modes are studied through temperature-dependent Raman spectra and first-principles density functional calculations. A significant decrease in the Raman frequencies below the Néel temperature is observed, which results from the strong spin−phonon coupling effect in 2D FeOCl. This study provides a highquality low-symmetry vdW magnetic candidate for miniaturized spintronics.

Engineering of hollow nanostructure, represented by the carbon nanocages, has shown tremendous potential in addressing the impedance mismatch of carbonaceous microwave absorbers (MAs). However, issues with limited electric energy loss capacity caused by their localized graphitization characteristic and the isolated 0D structural layout of these reported models still need to be settled. Herein, for the first time, a controllable structure of 3D interconnected framework assembled with graphene nanocages (3DIGCs) is constructed via a self‐sacrificing in‐situ growth. The elaborate air‐filled interconnected cavities impart desirable impedance matching to absorber and facilitate multi‐scattering of microwave; while the archipelago‐like continuous framework with a remarkable electrical conductivity (≈1265.8 S m−1) boosts their electric energy loss capacity by introducing resistance loss and a synergistic reinforcing effect from dipolar polarization and interfacial polarization, in which the loss behaviors are innovatively unraveled via numerical simulation technology explicitly, further highlighting the structural advantages of 3DIGCs. As a result, 3DIGC‐750 delivers a strong reflection loss of −51.10 dB and an effective bandwidth of 4.40 GHz at only 1.45 mm, outperforming the reported carbon nanocage MAs. This work hereby provides a deep insight into employing structure engineering to develop high‐performance graphene nanocage MAs.

Fe 3 O 4 has attracted tremendous interest in vast areas of biomedicine and catalysis as well as environment engineering. However, it is highly desired to fully understand the chemical kinetic process and propose a general, surfactantfree, large-scale synthesis approach for Fe 3 O 4 spheres. Herein, we developed a facile scalable solvothermal method in the absence of surfactants to produce Fe 3 O 4 spheres with the yield of 5.1 g, which present tunable sizes from 107 to 450 nm by modulated molar ratio of Fe 3+ /COO − in the solution. Particularly, it is observed that the reactants undergo a redox process, composed of a precipitation-dissolution equilibrium combined with a coordination reaction (termed as RPC), to the final product based on the LaMer model. It is worth noting that the generation of di-carboxyl group and its coordination with iron cations determine the formation of Fe 3 O 4 spheres. This work not only offers a strategy to precisely tailor the particle size in scalable synthesis process, but also gives the insight on the role of dihydric alcohol in the formation mechanism of Fe 3 O 4 spheres in the absence of surfactants.

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A soft template-assisted redox strategy has been developed to fabricate core–satellite Fe3O4@PPy/Pd nanocomposites as efficient nanocatalysts for reduction of nitroaromatics.