Latest ArticlesThe battery energy density can be improved by raising the operating voltage, however, which may lead to rapid capacity decay due to the continuous electrolyte decomposition and the thickening of electrode electrolyte interphases. To address these challenges, we proposed tripropyl phosphate (TPP) as an additive−regulating Li+ solvation structure to construct a stable LiF–rich electrode carbonate−based electrolyte interphases for sustaining 4.6 V Li||LiCoO2 batteries. This optimized interphases could help reduce the resistance and achieve better rate performance and cycling stability. As expected, the Li||LiCoO2 battery retained 79.4% capacity after 100 cycles at 0.5 C, while the Li||Li symmetric cell also kept a stable plating/stripping process over 450 h at the current density of 1.0 mA/cm2 with a deposited amount of 0.5 mAh/cm2.
The homochiral compounds play an important role in human health and pharmaceutical industry. Currently, the chromatographic enantioseparation has become one of the most effective and practical approach to obtain pure enantiomers. Herein, the exploration of advanced materials, using as chromatographic chiral stationary phases for racemic separation, has attracted great attention. Thanks to their high enantioselectivity and controllable synthesis, the emerging chiral metal-organic frameworks (CMOFs) have been widely studied as the stationary phase in chromatographic technology. In this review, we will summarize the principles of synthetic strategies and mechanism of chiral microenvironment. In particular, the recent progress and research hotspot of CMOFs regarding as the chiral stationary phases in gas chromatography (GC), high-performance liquid chromatography (HPLC), and capillary electrochromatography (CEC), are elucidated systematically according to the published work. Last but not the least, we also highlight the challenges and perspectives of rational design of CMOFs, as well as their corresponding racemic separation. We envision that the review will provide a further understanding of CMOFs and facilitate the development of chromatographic enantioselective applications.
Water pollution caused by Hg(II) and Ag(I) poses deleterious effects to environmental safety. Adsorption is one of the promising methods to decontaminate aqueous metal ions. Herein, polyhydroxyl-capped poly(amidoamine) (PAMAM) dendrimer/silica composites (G1-OH and G2-OH) were prepared for decontaminating aqueous Hg(II) and Ag(I). The maximum adsorption capacity of G1-OH and G2-OH for Hg(II) are 0.45 and 0.76 mmol/g, while that for Ag(I) are 0.66 and 0.81 mmol/g. The optimum solution pH for the adsorption of Hg(II) and Ag(I) are both 6. The adsorption for Hg(II) and Ag(I) can reach equilibrium at 150 and 120 min, respectively. Pseudo-second-order model can be used to describe the adsorption kinetic process and the rate-controlling step is film diffusion process. Adsorption isotherm indicates the adsorption can be promoted by increasing concentration and temperature, and the adsorption process could be described by Langmuir model with chemical mechanism. G1-OH and G2-OH exhibit excellent adsorption selectivity and they can 100% adsorb Hg(II) or Ag(I) with the coexisting of Fe(III), Co(II), Cu(II) or Ni(II). Adsorption mechanism confirms C-N, OH and CONH groups play critical role for the adsorption of the two ions. The work may provide efficient adsorbents for the decontamination of aqueous Hg(II) and Ag(I) with practical value.
Constructing synergistic active sites and optimizing the cooperative adsorption energies for hydrogen and hydroxyl based intermediates are two essential strategies to improve the sluggish kinetics of hydrogen evolution reaction (HER) in alkaline medium. However, it is still in its infancy to simultaneously achieve these goals, especially for designing a well-defined carrier with multiple hydroxyl adsorption sites. Herein, the Ni(HCO3)2 nanoplates (NHC) with horizontal interfaces sites of Ni-terminated NiO, NiOOH, NiCOO, and Ni(OH)2 were employed as the hydroxyl adsorption active sites, which could anchor Pt particles with hydrogen adsorption active sites, constructing the synergistic active sites (NHC-Pt) for HER catalysis. Evidenced by X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS), the NHC could affect the chemical state and electronic structure of Pt particles by forming bond of Pt-O which could reduce the reaction energy barriers, facilitate the adsorption of hydrogen and establishment of H–H bond. Furthermore, density functional theory (DFT) theoretical calculation revealed that the related process of hydroxide was the rate-determining step. It is demonstrated the hydroxyl group presents the lowest energy barrier for desorption in the process of HER when the gradual desorption process could be described as a migration from Ni(HCO3)2·OH directly or via other Ni-based systems formed after partial decomposition of nickel hydrocarbonate to Ni(OH)2···OH with following desorption. As a result, the NHC-Pt hierarchical nanostructure demonstrated superior activity towards HER in a pH-universal solution. This enhancement can be attributed to the optimized electronic structure of Pt, the migration of hydroxyl group on NHC substrates, and the synergistic effects between the NHC carrier and Pt particles.
Silicon based (Si-based) materials are considered to be the most promising anode materials for lithium-ion batteries (LIBs) due to their high specific capacity. However, the issues of poor electrical conductivity and volume expansion during cycling have not been effectively addressed. The optimum remedy is to select specific materials to establish an exceptional conductive and volume buffer structure to assist the Si materials to develop its excellent lithium storage properties. Here, Si particles were encapsulated into porous carbon fibers containing ultrafine Co particles (CP) to obtained Si-x@CP-y film. Among them, the addition of Si particles and the void structure was precisely regulated to achieve a superior electrode with a high specific capacity. Subsequently, the two-dimensional conductive material reduced graphene oxide (rGO) nanosheets were further incorporated to obtain Si-2@CP-2@rGO films with core@multi-shell structure. The final electrode was equipped with one-, two-, and three-dimensional electronic pathways to allow rapid electron transport, and featured with multi-layer buffer structure and reserved pores that could effectively mitigate volume changes. As expected, the free-standing Si-2@CP-2@rGO electrode delivered a high specific capacity of 1221.2 mAh/g after 100 cycles at 0.1 A/g in a half cell, and the assembled full cell showed 249.0 mAh/g after 200 cycles at 0.2 A/g, which fulfilled the lightweight requirement for new energy storage devices.
In recent years, host-guest interactions of macrocycles have emerged as a promising approach to effectively enhance pure organic room-temperature phosphorescence by inhibiting the nonradiative relaxation while isolating the effects of oxygen and water molecules. In this work, a supramolecular assembly Q[8]-BCPI was constructed by 6-bromoisoquinoline derivative (BCPI) and cucurbit[8]uril (Q[8]). The assembly produced intense green room temperature phosphorescence (RTP) emission and enabled supramolecular recognition and detection of l-tryptophan (L-Trp) and l-tyrosine (L-Tyr). Moreover, the Q[8]-BCPI assembly showed good biocompatibility and low biotoxicity, and had a good staining effect on HeLa cells.
Temperature plays a crucial role in regulating polymorphism in supramolecular polymers. Understanding the mechanism behind temperature-dependent supramolecular polymorphism is crucial as it provides an opportunity to tailor polymorphs for specific properties and applications. In this study, we present our findings on a naphthalimide-substituted benzene-1,3,5-tricarboxamide derivative, R-Nap-1, which exhibits two distinct polymerization pathways at varying temperatures. At 313 K, polymerization results in the formation of an M-chiral polymorph, whereas at 253 K, a P-chiral polymorph is formed. Both polymorphs are notably stable, remaining unchanged for over six months under ambient conditions. Theoretical calculations and experimental investigations allowed us to elucidate the mechanisms underlying these polymorphic transformations. The formation of the M-chiral polymorph at 313 K is attributed to the nucleation and growth of R-Nap-1 monomers once their concentration surpasses a critical threshold. Conversely, at lower temperatures (e.g., 253 K), the monomers undergo facile transformation into dimers due to a lower energy barrier and reduced Gibbs energy compared to the monomeric state. Subsequently, these dimers undergo nucleation-elongation to form the P-chiral polymorph when their concentration exceeds the critical polymerization concentration. The stability and lack of interconversion between the two polymorphs can be attributed to their close thermodynamic stabilities, as evidenced by variable-temperature CD spectra and DFT calculations. These findings highlight the importance of accurate temperature control in supramolecular polymerization processes, making a significant contribution to the understanding of supramolecular polymorphism, thus advancing the field of supramolecular chemistry.
Artificial synapses are essential building blocks for neuromorphic electronics. Here, solid polymer electrolyte-gated artificial synapses (EGASs) were fabricated using ITO fibers as channels, which possess an ultra-high sensitivity of 5 mV and a long-term memory time exceeding 3 min. Notably, digitally printed ITO-fiber arrays exhibit an ultra-high transmittance of approximately 99.67%. Biological synaptic plasticity, such as excitatory postsynaptic current, paired-pulse facilitation, spike frequency-dependent plasticity, and synaptic potentiation and depression, were successfully mimicked using the EGASs. Based on the synaptic properties of the EGASs, an artificial neural network was constructed to perform supervised learning using the Fashion-MNIST dataset, achieving high pattern recognition rate (82.39%) due to the linear and symmetric synaptic plasticity. This work provides insights into high-sensitivity artificial synapses for future neuromorphic computing.
Carbon-based materials with single-atom (SA) transition metals coordinated with nitrogen (M-Nx) have attracted extensive attention due to their superior electrochemical CO2 reduction reaction (CO2RR) performance. However, the uncontrolled recombination of metal atoms during the typical high-temperature synthesis process in M-Nx causes deterioration of CO2RR activity. Herein, by using electrospinning, we propose a novel strategy for constructing a highly active and selective SA Fe-modified N-doped porous carbon fiber membrane catalyst (Fe-N-CF). This carbon membrane has an interconnected three-dimensional structure and a hierarchical porous structure, which can not only confine Fe to be single atom as active centers, but also provide a diffusion channel for CO2 molecules. Relying on its special structure and stable mechanical properties, Fe-N-CF is directly used for CO2RR, which presents an excellent selectivity (CO Faradaic efficiency of 97%) and stability. DFT calculations reveals that the synthesized Fe-N4-C can significantly reduce the energy barrier for intermediate COOH* formation and CO desorption. This work highlights the specific advantages of using electrospinning method to prepare the optimal SA catalysts.
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