Graphene is highly desirable as an electromagnetic wave absorber because of its high dielectric loss and low density. Nevertheless, pure graphene is found to be non-magnetic and contributes to microwave energy absorption mostly because of its dielectric loss, and the electromagnetic parameters of pure graphene, which are out of balance, result in a bad impedance matching characteristic. In this paper, we report a facile solvothermal route to synthesize laminated magnetic graphene. The results show that there have been significant changes in the electromagnetic properties of magnetic graphene when compared with pure graphene. Especially the dielectric Cole-Cole semicircle suggests that there are Debye relaxation processes in the laminated magnetic graphene, which prove beneficial to enhance the dielectric loss. We also proposed an electromagnetic complementary theory to explain how laminated magnetic graphene, with the combined advantages of graphene and magnetic particles, helps to improve the standard of impedance matching for electromagnetic wave absorbing materials. Besides, microwave absorption properties indicate that the reflection loss of the as-prepared composite is below À10 dB (90% absorption) at 10.4-13.2 GHz with a coating layer thickness of 2.0 mm. This further confirms that the nanoscale surface modification of magnetic particles on graphene makes graphenebased composites have a certain research value in electromagnetic wave absorption.

A carbon-bridge effect was adopted to explain the electromagnetic wave absorbing property related to the cross-linked framework structure of RGO–SCI composites.

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N-doped ordered mesoporous carbon−Co composites (Co-N-OMC) with 2D hexagonal structure, uniform pore size (4.4 nm), high surface area (550 m 2 g −1 ), and medium pore volume (0.61 cm 3 g −1 ) were successfully fabricated through facile one-step template method. We employed resol as the carbon precursor, triblock copolymer as the template agent, and cobaltous acetate and urea as additives. XPS analysis revealed that nitrogen was successfully doped in ordered mesoporous carbon and existed in the form of pyridine-like and quaternary-N nitrogen atoms. More importantly, metallic Co nanoparticles with uniform diameter around 15 nm highly dispersed in carbon matrix without adding any dispersion agent, which was probably due to the confinement effect of mesoporous structure. It was unambiguously demonstrated by HRTEM analysis that there were layered graphitic sheets present around Co particles, resulting from in situ catalytic graphitization of amorphrous carbon by Co species. Pt catalyst deposited on Co-N-OMC composite showed an excellent electrocatalytic activity for both methanol oxidation and oxygen reduction reaction, which was probably due to its suitable pore structure, improved degree of graphitization, presence of nitrogen, and high dispersion of Pt nanoparticles.

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Conductive hydrogels have potential applications in shielding electromagnetic (EM) radiation interference in deformable and wearable electronic devices, but usually suffer from poor environmental stability and stretching-induced shielding performance degradation. Although organohydrogels can improve the environmental stability of materials, their development is at the expense of reducing electrical conductivity and thus weakening EM interference shielding ability. Here, a MXene organohydrogel is prepared which is composed of MXene network for electron conduction, binary solvent channels for ion conduction, and abundant solvent-polymer-MXene interfaces for EM wave scattering. This organohydrogel possesses excellent anti-drying ability, low-temperature tolerance, stretchability, shape adaptability, adhesion and rapid self-healing ability. Two effective strategies have been proposed to solve the problems of current organohydrogel shielding materials. By reasonably controlling the MXene content and the glycerol-water ratio in the gel, MXene organohydrogel can exhibit exceptionally enhanced EM interference shielding performances compared to MXene hydrogel due to the increased physical cross-linking density of the gel. Moreover, MXene organohydrogel shows attractive stretching-enhanced interference effectiveness, caused by the connection and parallel arrangement of MXene nanosheets. This well-designed MXene organohydrogel has potential applications in shielding EM interference in deformable and wearable electronic devices.

In this current contribution, we provide a detailed investigation into the photochemistry and the free radical photoinitiating reactivity of LED light-sensitive photoinitiators (PIs). This series was designed on the basis of a judicious association of a carbazole-coumarin fused subunit and an O-acyl-α-oxooxime branch, which integrates an N−O photocleavable bond. Within this molecular framework, several substitution changes affecting specifically two distinctive sites of the oxime group have been proposed to rationalize some relevant structure−reactivity relationships. We show that the photobleaching rates of the oxime esters (OXEs) are clearly influenced by an ethyl-to-isopropyl substitution effect on the oxime methine carbon whereas the photoinitiating efficiency is mainly driven by a O-benzyl-to-O-acetyl substitution change. Of particular interest, we show that the photoinitiating efficiencies of these OXEs largely depart from their respective absorption spectra in such manner that their photopolymerization performance can be amplified by more than 2 orders of magnitude between 365 and 425 nm LED irradiation. This effect clearly outperforms the photoinitiating efficiency of the commercially available Irgacure OXE-02 oxime ester used as a reference. In the proposed mechanism that accounts for this original wavelength-dependent photopolymerization property, we highlighted the role of an imine-based transient species whose reactivity toward the acrylate monomer can be phototriggered promoting thereby an alternative competing reaction sequence.

The effects of alkaline-earth metal cation (AMC: Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ ) substitution on the photoelectrochemical properties of phase-pure LaFeO3 (LFO) thin-films are elucidated by X-ray Photoemission Spectroscopy (XPS), X-ray Diffraction (XRD), diffuse reflectance and electrochemical impedance spectroscopy (EIS). XRD confirms the formation of single-phase cubic LFO thin films, with a rather complex dependence on the nature of the AMC and extent of substitution. Interestingly, subtle trends in lattice constant variations observed in XRD are closely correlated with shifts in the binding energies of Fe 2p3/2 and O 1s orbitals associated with the perovskite lattice. We establish a scaling factor between these two photoemission peaks, unveiling key correlation between Fe oxidation state and Fe-O covalency. Diffuse reflectance shows that optical transitions are little affected by AMC substitution below 10%, which are dominated by a direct bandgap transition close to 2.72 eV. Differential capacitance data obtained from EIS confirm the p-type characteristic of pristine LFO thin-films, revealing the presence of sub-bandgap electronic state (A-states) close to the valence band edge. The density of A-states is decreased upon AMC substitution, while the overall capacitance increases (increase in dopant level) and the apparent flat-band potential shifts towards more positive potentials. This behaviour is consistent with the change in the valence band photoemission edge. In addition, capacitance data of cation-substituted films show the emergence of deeper states centred around 0.6 eV above the valence band edge (B-states). Photoelectrochemical responses towards the hydrogen evolution and oxygen reduction reactions in alkaline solutions show a complex dependence on alkaline-earth metal incorporation, reaching incident-photon-to-current conversion efficiency close to 20% in oxygen saturated solutions. We rationalise the photoresponses of the LFO films in terms of the effect sub-bandgap states on majority carrier mobility, charge transfer and recombination kinetics.