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Controlling the porous defects in MoCx-carbon hybrids has been presented as an effective strategy for enhancing electromagnetic wave (EW) absorbing ability. To homogeneously distribute MoCx hetero-units into carbon matrix with high porosity and defect is of significance but hard to achieve. Herein, an excellent temperature-induced porous defect has been successfully constructed in the metallic Co-doped MoCx carbon composite. The proper calcination temperature on the “Host-Guest” structural CoMo-based crystalline precursor has derived the homogeneously distributed metallic Co and MoCx particles with the high number of mesoporous of ~ 20 nm and interfacial defects. Owing to the brilliant synergistic effect of polarization, magnetic loss and impedance matching, the superior RLmin of -47.72 dB at 11.76 GHz at the thickness of 2.0 mm and a wide effective absorption bandwidth (EAB) of 4.58 GHz (7.44 ~ 12.02 GHz) covered the whole X-band at the thickness of 2.5 mm for η-MoC/Co@NC-800 were observed. More importantly, the excellent heat-insulating performance of the η-MoC/Co@NC-800 derived ultralight aerogel composite has been developed, which is better than commercial materials. This work provides a valuable insight to facile constructing porous defects in EW absorbing materials and heat-insulating composite materials.

In situ constructing hetero-interface, and revealing its interfacial polarization is challenging. Here, the Mo defect-induced interfacial polarization on MoC(−)/NC(+) interface was clarified, and for the first time, directly observed by hologram.

Development of a novel strategy to tackle bacterial-contaminated complex industrial wastewaters containing refractory organic pollutants is of great demand. In this study, polydopamine (PDA)-coated magnetic cellulose nanofiber (MCNF)-loaded silver nanoparticle (AgNP) (MCNF/PDA-Ag) nanocomposites were designed and applied for efficient degradation of organic dye pollutants and inactivation of

Flexible electrochromic devices (FECDs) have been regarded as an ideal stratagem for wearable displays. However, it remains a great challenge to achieve long-term stability for high-performance FECDs due to their severe electrolyte deformation/leakage under repeated bending. Herein, inspired by the rough and fluffy microstructure of cobwebs, we prepared a porous polylactic acid (PLA) network through electrospinning and nonsolvent-induced phase separation. This loosely interlaced PLA network can be well infiltrated by electrolytes and exhibits extraordinarily high transparency; in addition, its surface contains numerous tiny holes to effectively load electrolytes to mitigate deformation. Furthermore, we also introduced silver nanowires (AgNWs) as the supporting network to load and connect electrochromic materials. After assembling them with graphene (GR) electrodes, a wearable FECD with a quintuple network structure (two GR networks, two AgNW networks, and one PLA network) was successfully prepared. The resulting FECD can realize high optical modulation (more than 70%), excellent cyclic stability (retain 95% after 1000 cycles), and innovative bending resistance (retain 84.8% after 6000 bending cycles). This work not only solves the long-lasting challenge of developing FECD with high optical modulation and bending resistances but also provides an energetic paradigm for diverse soft electronics used in harsh environments.

Manipulation of long-lived triplet excitons in organic molecules is key to applications including next-generation optoelectronics, background-free bioimaging, information encryption, and photodynamic therapy. However, for organic room-temperature phosphorescence (RTP), which stems from triplet excitons, it is still difficult to simultaneously achieve efficiency and lifetime enhancement on account of weak spin-orbit coupling and rapid nonradiative transitions, especially in the red and near-infrared region. Herein, we report that a series of fluorescent naphthalimides-which did not originally show observable phosphorescence in solution, as aggregates, in polymer films, or in any other tested host material, including heavy-atom matrices at cryogenic temperatures-can now efficiently produce ultralong RTP (ϕ=0.17, τ=243 ms) in phthalimide hosts. Notably, red RTP (λRTP =628 nm) is realized at a molar ratio of less than 10 parts per billion, demonstrating an unprecedentedly low guest-to-host ratio where efficient RTP can take place in molecular solids.

Thermally activated delayed fluorescence (TADF) materials utilizing purely organic compounds have become a promising and more eco-friendly alternative to phosphorescent organometallic emitters in organic light-emitting diode (OLED) devices. However, the modulation of luminescence properties for molecules with a high degree of structural complexity remains challenging. Herein, by combining the aromatic electrophilic directing (AED) and intramolecular charge transfer (ICT) effects, two OLED emitters containing an electron donor (triphenylamine, TPA) and acceptor (benzophenone) covalently linked via a carbazole ring were synthesized and compared. The design concomitantly allows for spatial separation of origin/destination orbitals involved in the lowest singlet excited state and increased density of charge carriers in contrast to a non-conjugated linker. More conveniently, we demonstrate that increased acceptor strength by cyano-substitution results in a significant decrease of the singlet–triplet energy gap from 0.23 to 0.09 eV. The latter exhibits a TADF photoluminescence quantum yield of up to 63% with a lifetime of 7.67 μs in the OLED matrix. Notably, the OLED device using the cyano-TADF molecules as the emitting layer possesses an enhanced external quantum efficiency of 15.6%, compared to 10.3% efficiency obtained from the non-substituted version, and small efficiency roll-off, demonstrating the modulation versatility of purely organic molecule-based OLED devices.

Chiral recognition with molecular luminescence is a beneficial but challenging method due to an often lack of dramatic difference in intermolecular interactions between the chiral analyte/substrate pair versus their enantiomeric counterpart. Here we show that the difference in room-temperature phosphorescence (RTP) can be substantially augmented by employing guest-host energy-transfer systems. By covalent attachment of chiral amino compounds to a phthalimide host and a naphthalimide guest, respectively, RTP intensity difference of two orders of magnitude with a detection limit of >98% enantiomeric excess (ee) could be achieved. For example, S-enantiomeric guests in S-enantiomeric hosts produce strong red RTP afterglow while no appreciable RTP could be observed in an S/R guest-host combination. The huge spectroscopic difference in RTP results in conspicuous steady-state and delayed-emission variations, which could easily be discriminated by the naked eye. A generalized concept in solid-state RTP chiral recognition is proposed to expand the application scope of the reported method.

A new strategy was devised for estimating and screening pKa values among different carbon acids under ambient conditions by using the UV/Vis absorption spectrum of persistent radical pairs (PRPs), which are generated from an N-substituted naphthalimide (NNI) derivative in the presence of various carbanions in organic solutions. The electron paramagnetic resonance (EPR) spectroscopy was used to examine the presence of radicals. Unexpectedly, it was discovered that the UV/Vis spectrum of PRPs reveals a distinct linear relationship between the PRP absorption and the pKa value of a corresponding carbon acid, which is likely due to the energy difference among different RPRs. The finding may offer organic chemists an alternative reference to conduct carbanion-mediated reactions in various organic solutions.

Organic luminogens with persistent room-temperature phosphorescence (RTP) have found a wide range of applications. However, many RTP luminogens are prone to severe quenching in the crystalline state. Herein, we report a strategy to construct a donor-sp3 -acceptor type luminogen that exhibits aggregation-induced emission (AIE) while the donor-sp2 -acceptor counterpart structure exhibits a non-emissive solid state. Unexpectedly, it was discovered that a trace amount (0.01 %) of the structurally similar derivative, produced by a side reaction with the DMF solvent, could induce strong RTP with an absolute RTP yield up to 25.4 % and a lifetime of 48 ms, although the substance does not show RTP by itself. Single-crystal XRD-based calculations suggest that n-σ* orbital interactions as a result of structural similarity may be responsible for the strong RTP in the bicomponent system. This study provides a new insight into the design of multi-component, solid-state RTP materials from organic molecular systems.

N-Substituted naphthalimides (NNIs) have been shown to exhibit highly efficient and persistent room-temperature phosphorescence from an NNI-localized triplet excited state, when the N-substitution is a sufficiently strong donor and mediates an intramolecular charge-transfer (ICT) state upon photo-excitation. This work shows that, when the electron-donating ability of the N-substitution is further increased in the presence of a carbanion or phenoxide, spontaneous electron transfer (ET) occurs and results in radical anions, verified with electron-paramagnetic resonance (EPR) spectroscopy. However, the EPR-active anion is surprisingly persistent and impervious to nucleophilic and radical reactions under anionic conditions. The stability is thought to originate from an intramolecular spin pairing between the N-donor and the NI acceptor post ET, which is demonstrated in supramolecular chemistry.

Polyaniline materials are widely utilized as electrodes for supercapacitors because of low cost, facile synthesis, high mechanical flexibility and theoretical high specific capacitance. However, the poor cycle stability and low rate capability restrict their practical applications. Integration of polyaniline with carbon materials is an effective strategy to solve the aforementioned limitations. In this review, polyaniline electrode materials, especially in the forms of different nanostructures, are firstly summarized to demonstrate the general merits of polyaniline-carbon composites for supercapacitors. Subsequent emphasis focuses on the rational design of the composites with various carbon materials, including activated carbon, porous carbon, carbon nanotubes, carbon fibers, graphene or their hybrids. The importance of the compositions, desired architectures and synergistic interactions on the enhanced electrochemical properties is emphasized. In particular, the research trends in the configurational design of unconventional devices, such as flexible, stretchable, compressible and asymmetric supercapacitors with excellent performance at different states (bending, stretching, compressing and/or folding). The review ends with a summary and discusses the perspectives and challenging issues regarding the rational design of flexible supercapacitors in future studies, along with the current outlook for the integrated electronic devices.

Bacterial cellulose/polyaniline (BC/PANI) nanocomposites display many potential applications in various fields. However, the conductivity and mechanical properties remain a challenge. Here, we developed a novel method to prepare BC/PANI nanocomposites via the chemical grafting of PANI onto epoxy modified BC (EBC), followed by the grafting of polyacrylamide (PAM). For comparison, an in situ BC/PANI sample was also prepared. The grafting reaction between PANI and EBC and the retention of PANI on EBC were confirmed by FTIR, X-ray photoelectron spectroscopy, and elemental analysis. The cross-section morphology of BC transformed into a three-dimensional and continuous network structure with the incorporation of PANI. The effects of epoxy and PAM contents on the morphology, conductivity, and mechanical properties of PANI-g-EBC and PANI-g-EBC3/PAM nanocomposites were investigated. Compared with those of the in situ BC/PANI sample, the conductivity of PANI-g-EBC increased from 0.12 to 1.08 S/cm, while the stress ...

Room-temperature phosphorescent (RTP) materials have been widely used in sensing, imaging and display technology. The ability to predict and modulate RTP properties, such as emission color and lifetime, is particularly important for the design of rational materials. Here, we show that by incorporating three different types of acceptor moieties into a polylactide (PLA)-substituted carbazole donor, RTP with different emission colors and lifetimes (with an absolute quantum yield of up to 39.4%) could be generated. Specifically, the chemical conjugation between an n–π* type of luminophore and a π–π* one most likely results in dual RTP while the conjugation between two π–π* types of luminophores produces fluorescence-RTP (F-RTP) dual emission. The consistency between the experimental results and theoretical calculations further validates the observation. To demonstrate the versatility and application potential of these purely organic, biocompatible materials, aqueous nanoparticles were fabricated and used as high-contrast cell imaging agents, given the large Stokes shift of RTP materials.

Purely organic phosphors have important applications in imaging, sensing, informatics and illumination. Methoxy-substituted difluoroboron dibenzoylmethane (BF2dbm) complexes exhibit intense fluorescence with an almost unity quantum yield. Here we show that by simply introducing an sp3 oxygen-bridged methoxylphenyl group as a pendant to BF2dbm, the boron complex exhibits a triplet quantum yield of 0.16, a more than 100-fold increase compared to that of BF2dbm.