Latest ArticlesThe integration of lanthanide (Ln) ions and polyoxoniobates (PONbs) is challenging, and the known Ln-substituted PONbs are still scarce. This work introduces high-nuclear iso-Ln-oxo clusters into the PONb system. The first series of high-nuclear Ln-oxo clusters encapsulated heterometallic polyoxoniobates H9[Na(H2O)4][Cu(en)2]10{Ln6(μ3-OH)6(SiNb18O54)3}·18H2O (1-Ln, en = ethylenediamine, Ln = Dy, Gd, Tb, Ho, Er, Tm, Yb, Lu) based on flower-like {Ln6(μ3-OH)6(SiNb18O54)3} ({Ln6Si3Nb54}) clusters have been successfully synthesized via one-pot hydrothermal synthesis strategy. The flower-like polyoxoanion {Ln6Si3Nb54} is consisted of three heteropolyoxoniobate {SiNb18O54} clusters and one unique planar equilateral triangle-shaped {Ln6(μ3-OH)6} cluster, which presents the highest nuclear iso-Ln-oxo cluster in PONb chemistry. In {Ln6(μ3-OH)6} cluster, each pair of μ3-OH groups link three Dy3+ ions to form a small approximate equilateral triangle-shaped {Dy3(OH)2} cluster. Furthermore, the three {Dy3(OH)2} clusters comprise a bigger approximate equilateral triangle-shaped {Dy6(μ3-OH)6} cluster. The reported hexanuclear {Ln6} cluster skeletons are mostly octahedral, however, such equilateral triangle-shaped skeleton of the hexanuclear Ln-oxo cluster is first observed. The 1-Dy exhibits good water vapor adsorption capacity and ferromagnetic properties.
Interphase strain engineering provides a unique methodology to significantly modify the lattice structure across a single film, enabling the emergence and manipulation of novel functionalities that are inaccessible in the context of traditional strain engineering methods. In this work, by using the interphase strain, we achieve a ferromagnetic state with enhanced Curie temperature and a room-temperature polar state in EuO secondary phase-tunned EuTiO3 thin films. A combination of atomic-scale electron microscopy and synchrotron X-ray spectroscopy unravels the underlying mechanisms of the ferroelectric and ferromagnetic properties enhancement. Wherein, the EuO secondary phase is found to be able to dramatically distort the TiO6 octahedra, which favors the non-centrosymmetric polar state, weakens antiferromagnetic Eu-Ti-Eu interactions, and enhances ferromagnetic Eu-O-Eu interactions. Our work demonstrates the feasibility and effectiveness of interphase strain engineering in simultaneously promoting ferroelectric and ferromagnetic performance, which would provide new thinking on the property regulation of numerous strongly correlated functional materials.
Metal-organic frameworks (MOFs) as promising electrodes for supercapacitors are attracting increasing research interest. Herein, we report an effective strategy to improve the electrochemical performance of Ni-MOF for supercapacitor by introducing a secondary Co ion. The Co substitution of Ni in Ni-MOF can improve the intrinsic reactivity and stability. As a result, the bimetallic Co/Ni-MOF-1:15 with an optimal Co/Ni ratio delivers high specific capacitance (359 F/g at 0.5 A/g), good rate performance (81.5% retention at 5 A/g) and cycling stability (81% retention after 5000 cycles). These results demonstrate that the bimetallic synergistic strategy is an effective way to improve the pseudocapacitive performance of MOFs.
A photoactive polyoxometalate-based metal−organic framework (POMOF), NiW-DPNDI, was synthesized by combination of Ni(Ⅱ) ions, [ZnW12O40]6‒ anions, and N, N'-bis(4-pyridylmethyl)naphthalene diimide (DPNDI) molecules into one single framework. NiW-DPNDI displays a three-dimensional structure by the strong anion⋯π interactions between the trapped [ZnW12O40]6‒ anions and the electron-deficient naphthalenic ring centroids and the π−π stacking interactions between DPNDI moieties. NiW-DPNDI displayed a highly efficient hole-electron separation and ordered electron transfer under irradiation, thus ensuing its excellent photocatalysis in oxidation of styrene to produce benzaldehyde. In addition, it gave a high efficiency for styrene oxide under thermocatalytic conditions. Because the carbonic anhydrase (CA)-mimicking Ni sites and the negative electron-enriched [ZnW12O40]6‒ anions are well aligned in the pores, it can promote the cycloaddition of CO2 with epoxides under mild conditions.
Owing to the further requirement for electric vehicle market, it is appropriate to lower the cost and improve the energy density of lithium-ion batteries by adopting the Co-free and Ni-rich layered cathodes. However, their practical application is severely limited by structural instability and slow kinetics. Herein, ultrahigh-nickel cobalt-free LiNi0.9Mn0.1O2 cathode is elaborate designed via in-situ trace substitution of tungsten by a wet co-precipitation method following by high-temperature sintering. It is revealed that the in-situ doping strategy of high valence W6+ can effectively improve the structure stability by reducing irreversible phase transition and suppressing the formation of microcracks. Moreover, the transformed fine particles determined by W-doping can facilitate the kinetic characteristics by shortening Li+ diffusion paths. As expected, 0.3 mol% W-doped LiNi0.9Mn0.1O2 cathode exhibits a high specific capacity of 143.5 mAh/g after 200 cycles at high rate of 5 C in the wide potential range of 2.8-4.5 V, representing a potential next-generation cathode with low-cost, high energy-density and fast-charging capabilities.
Lithium batteries have been widely used in all over the world for its high energy density, long-term cycle stability. While the resources of lithium metal and transition metal are limited, which restrict their applications in the grid energy storage. Dual ion sodium batteries (DISBs) possess higher energy density, especially owning high power density for its higher operating voltage (> 4.5 V). Nevertheless, the poor oxidation tolerance of carbonate electrolyte and the co-intercalation of solvents accompanied with anions are main obstacles to make the DISBs commercialization. Herein, a physical barrier (artificial SEI film) is pre-constructed in the Na||graphite batteries to solve these thorny problems. With the CSMG (covered SEI on modified graphite), batteries deliver higher capacity 40 mAh/g even under the current density of 300 mA/g and the capacity retention maintains very well after 100 cycles at a high operating voltage. Moreover, the function mechanism was revealed by in-situ XRD, demonstrating that the pre-constructed SEI can effectively suppress the irreversible phase transition and exfoliation of graphite, resulting from the co-intercalation of anions. Additionally, the work voltage windows of carbonate electrolyte are significantly broadened by establishing electrode/electrolyte interphase. This method opens up an avenue for the practical application of DISBs on the grid energy storage and other fields.
Zinc indium sulfide (ZnIn2S4), a novel photocatalyst, has attracted considerable attention and been extensively studied over the past few years owing to its various advantages such as nontoxicity, structural stability, easy availability, suitable band gap and fascinating photocatalytic activity. This review mainly focuses on the recent state-of-art progress of ZnIn2S4-based photocatalysts. First, we briefly introduced preparation methods of ZnIn2S4 with diverse morphological structures. Then, considering the photocatalytic activity of pristine ZnIn2S4 would be confined by rapid recombination of photo-generated electron-hole pairs and limited light absorption range, different modulation strategies such as layer and size control, doping, vacancy engineering and hetero-nanostructures were expounded in detail. Afterwards, the applications of ZnIn2S4 in various fields such as H2 production, CO2 reduction, value-added products synthesis, pollutant purification and N2 fixation are clearly summarized. In the end, we sorted out the conclusions and outlook, aiming to provide some new insights for this fascinating material.
Ultra-long room temperature phosphorescence (URTP) has been increasingly recognized in pure organic luminophor in recent years. Through a simpler molecular design and charge separation-recombination pathway, organic luminophor can achieve even better URTP properties. In this work, we achieved URTP in a system of host-guest doped benzophenone derivatives whose phosphorescence is visible to the naked eye. The differences in the wavelength lifetimes of luminescent emission correspond to different photophysical mechanisms. Through a combination of theoretical calculations and experiments, the host acts as a powerful substrate that restricts the motion of the guest and inhibits the non-radiative transitions of the guest, accompanied by a charge transfer separation-recombination process between the host and the guest, resulting in an URTP phenomenon. Transient absorption results demonstrate the existence of a charge-separated state. The design strategy via charge separation is generic and easy to implement, providing a direction for the future design of doped URTP.
The first example of TBAI/H2O cooperative electrocatalytic coupling-annulation of quinoxalin-2(1H)-ones with N-arylglycines was developed. A broad range of tetrahydroimidazo[1,5-a]quinoxalin-4(5H)-ones were obtained in good to excellent yields with exclusive chemoselectivities and excellent regioselectivities. The H-hydrogen bond served as a key factor for the electrocatalytic production of aminomethyl radical at lower oxidative potential.