Latest ArticlesElectrochromic devices (ECDs) have exhibited promising applications in the fields of energy-saving intelligent buildings and next-generation displays because of their simple structure, low power consumption, and multicolor displays. W18O49/polyaniline (PANI) hybrid films are prepared and assembled to ECDs. Compared with pure PANI and W18O49 films, the hybrid film exhibits superior electrochemical and electrochromic performance, including high optical modulation (70.2%), large areal capacity (79.6 mF/cm2), and good capacitance retention. The excellent electrochemical and electrochromic performance is ascribed to the formation of the donor (PANI)-acceptor (W18O49) pair, the porous structure in the nanowires, and the large surface area, which enhance electron delocalization of the W18O49/PANI, improve the ion diffusion rate, and increase the charge storage sites. Furthermore, benefitting from the outstanding optical, electrical, and multifunctional properties, the W18O49/PANI hybrid film-based ECD platform is expected to play an important role in electrochromism and energy storage.
Silver selenide thin film is one of the best candidates for thermoelectric devices. In the previous report, we demonstrated that high-performanced [201] oriented β-Ag2Se thin films can be prepared by direct metal surface element reaction (DMSER) solution selenization in a really short time at room temperature. However, the underlying mechanism of the fast reaction process were not discussed in depth. Herein, based on hard soft acid base (HASB) theory and strong oxidation, we further explored the possible reaction mechanism of the in-situ growth of β-Ag2Se thin films as the function of the reaction time. The time-dependent experimental results showed that the formation of the β-Ag2Se on elemental Ag precursor (~690 nm thick) in Se/Na2S precursor solution is in a growth driven mode with no obvious orientation or growth rate selections to the elemental Ag precursors. Our investigations provide a prerequisite for the further preparation of thermoelectric materials with excellent properties.
The abuse of antibiotics has brought great harm to the human living environment and health, so it is extremely significant to develop an efficient and simple method to detect trace antibiotic residues in various wastewaters. Herein, a new two-dimensional (2D) Cd-based metal−organic framework (Cd-MOF, namely LCU-111) and its mixed matrix membranes (MMMs) is sifted as luminescence sensors for efficient monitoring antibiotic nitrofurazone (NFZ) in various aqueous systems and applied as visible fingerprint identifying. The LCU-111 has good selectivity, sensibility, reproducibility and anti-interference for luminescent quenching NFZ with low detection limits (LODs) of 0.4567, 0.3649 and 0.8071 ppm in aqueous solution, HEPES biological buffer, and real urban Tuhai River water, respectively. Interestingly, the luminescent test papers and MMMs allow the NFZ sensing easier and more rapid by naked eyes, only with a low LOD of 0.8117 ppm for MMMs sensor. Notably, by combining multiple experiments with density functional theory (DFT) calculations, the photo-induced electron transfer (PET) quenching mechanism is further elucidated. More importantly, potential practical applications of LCU-111 for latent fingerprint visualization provide lifelike evidences for effective identification of individuals, which can be applied in criminal investigation.
Fluorescent materials that respond to multiple stimuli have broad applications ranging from sensing and bioimaging to information encryption. Herein, we report the design and synthesis of a single-fluorophore-based amphiphile DCSO, which shows temperature-, solvent-, humidity-, and radiation-dependent fluorescence. DCSO consists of a dicyanostilbene (DCS) group as a rigid hydrophobic core with oligo(ethylene glycol) (OEG) chains at both ends as a flexible hydrophilic periphery. The DCS group acts as a highly efficient fluorophore, while the OEG chain endows the molecule with thermo-responsiveness. Fluorescent colors can vary from blue to green to yellow in response to external stimuli. On the basis of light radiation, we demonstrate that this system can be applied to time-dependent information encryption, in which the correct information can only be read at a specific time under irradiation. This work further demonstrates the usefulness and application of single-fluorophore-based luminescent materials with multiple stimuli-responsive functions.
A new cooperative nickel reductive catalysis and N,N-dimethylformamide-mediated strategy for umpolung C–S radical reductive cross coupling of S-(trifluoromethyl)arylsulfonothioates with alkyl halides to produce alkyl aryl thioethers is described. This reaction features excellent selectivity, wide functionality tolerance, broad substrate scope, and facile late-stage modification of biologically relevant molecules. Mechanistic studies recognize initial generation of an amidyl radical anion via thermoinduced reduction of DMF with Sn, followed by umpolung reduction and single electron transfer of the nucleophilic sulfonyl moiety to form a sulphydryl radical and engage the Ni0/NiⅠ/NiⅢ/NiⅠ catalytic cycle.
Benzene is a volatile organic compound that can seriously harm human health, while it can serve as a precursor to produce chemicals of more complex structures in chemical industry. Capturing benzene using adsorbents is of great importance for human health, when the separation of hydrocarbons including benzene from crude oil was referred to as one of the “seven chemical separations to change the world”. In this work, we reported the efficient and selective separation of benzene from BTX and cyclohexane by hydrogen bonding self-assembly nonporous adaptive crystals AdaOH for the first time under mild and user-friendly conditions. Separation of benzene and cyclohexane (v/v = 1:1) can be achieved by AdaOH with a purity of benzene up to 96.8%. Separation of BTX (v/v; benzene:toluene:o-xylene:m-xylene:p-xylene= 1:1:1:1:1) can be achieved by AdaOH with a purity of benzene increased from 20% to 82.9%. Our results suggest that separation of benzene using the activated AdaOH as a non-porous adaptive crystal for selectively and efficiently capturing benzene can solve the challenge in separation of benzene from other chemicals such as cyclohexane in chemical industry, and can be helpful for removal of benzene that is released from the vehicles to air. The advantages of commercially availability, easy preparation, high separation efficiency and selectivity for benzene might endow this material with enormous potential for practical uses in areas like petrochemical industry.
Highly selective conversion of methane (CH4) to methanol (CH3OH) is an emerging attractive but challenging process for future development of hydrogen economy, which requires efficient catalysts. Herein, we systematically explore the catalytic properties of Pt(111) overlayer on transition metal oxides (TMOs) for CH4 conversion by first principles calculations. The Pt(111) monolayer supported by Ce-terminated CeO2(111) substrate exhibits high activity and selectivity for CH4 conversion to CH3OH, with the kinetic barrier of rate-limiting step of 1.05 eV. Intriguingly, the surface activity of Pt overlayer is governed by its d-band center relative to the energy of bonding states of adsorbed molecules, which in turn depends on the number of charge transfer between Pt(111) monolayer and underlying TMOs substrates. These results provide useful insights in the design of metal overlayers as catalysts with high-ultra performance and atomic utilization.
The solid electrolyte interphase (SEI), a passivation film covering the electrode surface, is crucial to the lifetime and efficiency of the lithium-ion (Li-ion) battery. Understanding the Li-ion diffusion mechanism within possible components in the mosaic-structured SEI is an essential step to improve the Li-ion conductivity and thus the battery performance. Here, we investigate the Li-ion diffusion mechanism within three amorphous SEI components (i.e., the inorganic inner layer, organic outer layer, and their mixture with 1:1 molar ratio) via ab initio molecular dynamic (AIMD) simulations. Our simulations show that the Li-ion diffusion coefficient in the inorganic layer is two orders of magnitude faster than that in the organic layer. Therefore, the inorganic layer makes a major contribution to the Li-ion diffusion. Furthermore, we find that the Li-ion diffusivity in the organic layer decreases slightly with the increase of the carbon chain from the methyl to ethyl owing to the steric hindrance induced by large groups. Overall, our current work unravels the Li-ion diffusion mechanism, and provides an atomic-scale insight for the understanding of the Li-ion transport in the SEI components.
In this work, taking NiSe2 as a prototype to be used as cocatalyst in photocatalytic hydrogen evolution, we demonstrate that the crystal phase of NiSe2 plays a vital role in determining the catalytic stability, rather than activity. Theoretical and experimental results indicate that the phase structure shows negligible influence to the charge transport and hydrogen adsorption capacity. When integrating with carbon nitride (CN) photocatalyst forming hybrids (m-NiSe2/CN and p-NiSe2/CN), the hybrids show comparable photocatalytic hydrogen evolution rates (3.26 µmol/h and 3.75 µmol/h). Unlike the comparable catalytic activity, we found that phase-engineered NiSe2 exhibits distinct stability, i.e., m-NiSe2 can evolve H2 steadily, but p-NiSe2 shows a significant decrease in catalytic process (~57.1% decrease in 25 h). The factor leading to different catalytic stability can be ascribed to the different surface conversion behavior during photocatalytic process, i.e., chemical structure of m-NiSe2 can be well preserved in catalytic process, but partial p-NiSe2 tends to be converted to NiOOH.
Spectroscopic study of water splitting by neutral metal clusters is crucial to understanding the microscopic mechanism of catalytic processes but has been proven to be a challenging experimental target due to the difficulty in size selection. Here, we report a size-specific infrared spectroscopic study of the reactions between neutral group 3 metals and water molecules based on threshold photoionization using a vacuum ultraviolet laser. Quantum chemical calculations were carried out to identify the structures and to assign the experimental spectra. All the M2O4H4 (M = Sc, Y, La) products are found to have the intriguing M2(μ2-O)(μ2-H)(μ2-OH)(η1-OH)2 structures, indicating that the HOH bond breaking, the MO/MH/MOH bond formation, and hydrogen production proceed efficiently in the reactions between laser-vaporized metals and water molecules. The joint experimental and theoretical results on the atomic scale demonstrate that the water splitting by neutral group 3 metals is both thermodynamically exothermic and kinetically facile in the gas phase. These findings have important implications for unravelling the structure-reactivity relationship of catalysts with isolated metal atoms/clusters dispersed on supports.
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