Latest ArticlesThe development of low-cost and high-performance ZnO Schottky photodetectors (PDs) has drawn intensive attention, but still a challenge due to their poor conductivity and low light utilization efficiency. Here, we introduce Ti3C2TX into ZnO films to fabricate Schottky UV PDs via facile spin-coated method. The fabricated ZnO/Ti3C2TX/ZnO compound film shows outstanding performance on photocurrent, responsivity, noise equivalent power (NEP), normalized detection rate (D*), and linear dynamic region (LDR), compared with the original ZnO device. The photocurrent is significantly increased by 466%, and the responsivity is improved by one order of magnitude. In addition, it exhibits relatively low NEP (5.99 × 10−11 W), strong D* (2.53 × 109 Jones), and high LDR (28 dB). The superior performance is ascribed to the enhanced conductivity and light absorption of ZnO film after introduction of Ti3C2TX modification layer, leading to simultaneously faster electron transfer, lower the radiation recombination of electron and holes on the ZnO/Ti3C2TX/ZnO compound film. This work provides a facile way to develop low-cost and high-performance ZnO Schottky PDs.
Free-standing electrodes are promising candidates for flexible rechargeable batteries, toward the application of flexible energy storage devices, due to their merits of additive-free, lightweight, and high energy density. Herein, we report a free-standing SnNb2O6@CSN flexible film with SnNb2O6 encapsulated in 3D carbon skeleton nanofibers by electrospinning and carbonization processes as flexible anode for sodium-ion batteries (SIBs). The 3D carbon skeleton nanofibers serve as ion/electron transport pathway to improve the electrochemical reaction kinetics and meanwhile alleviate the volume changes of SnNb2O6 during charge-discharge processes. The as-constructed half-cell (SnNb2O6@CSN‖Na) exhibits excellent cycling stability of 99.2 mAh/g at 0.5 A/g after 950 cycles (coulombic efficiency of ~100%) and a high rate performance of 108.6 mAh/g at 10 A/g. In addition, the pouch cell can light up the LEDs at different bending angles (0°, 90°, 180°). This research shows a promising anode material for flexible energy storage electronics.
Localized high-concentration electrolytes (LHCE) have shown good compatibility with high-voltage lithium (Li)-metal batteries, but their practicality is yet to be proved in terms of cost and safety. Here we develop a hybrid-LHCE with favorable integrated properties by combining the merits of two representative diluents, fluorobenzene (FB) and 1, 1, 2, 2-tetrafluoroethyl-2, 2, 2-trifluoroethyl ether (TFE). Specifically, the extremely cheap and lightweight FB significantly reduces the cost and density of electrolyte, while the fire-retardant TFE circumvents the flammable nature of FB and thus greatly improves the safety of electrolyte. Moreover, the FB–TFE mixture enhances the thermodynamic stability of hybrid-LHCE and renders a controllable defluorination of FB, contributing to the formation of a thin and durable inorganic-rich solid electrolyte interphase (SEI) with rapid ion-transport kinetics. Benefiting from the designed hybrid-LHCE, a Li|NCM523 battery demonstrates excellent cycling performance (215 cycles, 91% capacity retention) under challenging conditions of thin Li-anode (30 µm) and high cathode loading (3.5 mAh/cm2).
Non-centrosymmetric chalcogenides are attracting considerable attention as highly promising infrared nonlinear optical (IR-NLO) candidates, but it is challenging to simultaneously achieve sufficient second-harmonic-generation coefficient (deff > 0.5 × AgGaS2) and large energy gap (Eg > 3.5 eV). In this work, a novel ternary chalcogenide, Cs5Ga9S16 with an ultra-wide Eg of 4.05 eV, has been successfully obtained. This sulfide belongs to the monoclinic space group Pn (No. 7) with a novel 3D anionic [Ga9S16]5– framework that is formed by super-polyhedral [Ga9S23] units through corner-sharing S atoms. Such a unique crystal structure displays desirable characteristics which indicate a promising IR-NLO candidate: favourable phase-matching feature, sufficient deff (0.7 × AgGaS2), ultrahigh laser-induced damage threshold (31.6 × AgGaS2) and broad transparent region (0.27−14.96 µm). In addition, systematic theoretical studies and structural analysis suggest that the desirable IR-NLO performances can be attributed to the super-polyhedral building blocks. This finding may provide useful insight into the understanding and designing other high-performance IR-NLO candidates with super-polyhedral-built structures.
78Li2S-22P2S5 are sulfide electrolytes with high lithium-ion conductivity and wide electrochemical windows in the Li2S-P2S5 system, making them attractive solid electrolytes for ASSLBs. However, the role and potential of 78Li2S-22P2S5 solid electrolytes over a wide temperature range are still not fully understood. Therefore, we constructed solid-state batteries with NCM622 as the positive electrode and 78Li2S-22P2S5 glass-ceramics as the electrolyte to investigate in depth the differences in battery performance over a wide temperature range and their intrinsic mechanisms. The in-situ impedance and relaxation time distribution (DRT) demonstrated the electrochemical stability of the electrolyte over a wide temperature range, while the in-situ stacking pressure observed a large volume change during cycling at 60 ℃, leading to local solid-solid contact failure and poor cycling stability. This study provides insight into the advantages and problems of 78Li2S-22P2S5 in the wide temperature range as well as a basis for the construction of ASSLBs with high energy density and long cycle life.
With the quick development of sustainable energy sources, aqueous zinc-ion batteries (AZIBs) have become a highly potential energy storage technology. It is a crucial step to construct desired electrode materials for improving the total performance of AZIBs. In recent years, considerable efforts have focused on the modification of vanadium-based cathode materials. In this review, we summarized defect engineering strategies of vanadium-based cathodes, including oxygen defects, cation vacancies and heterogeneous doping. Then, we discussed the effect of various defects on the electrochemical performance of electrode materials. Finally, we proposed the future challenges and development directions of V-based cathode materials.
The cooperative effect plays a significant role in understanding the intermolecular donor-acceptor interactions of hydrogen bonds (H-bonds, D-H···A). Here, using the coupled-cluster singles and doubles with perturbative triple excitations (CCSD(T)) method of high-precision ab initio calculations, we show that the intermolecular H-bonded systems with different D and A atoms reproduce the structural changes predicted by the well-known cooperative effect upon intermolecular compression. That is, with decreasing intermolecular distance, the D-H bond length first increases and then decreases, while the H···A distance decreases. On the contrary, when D and A are the same, as the intermolecular distance decreases, the D-H bond length decreases without increasing. This obvious difference means that the cooperative effect may not be generally characterized by intermolecular compression. Interestingly, further analyses of many intermolecular systems confirm that this failure has boundaries, i.e., cooperative systems at their respective equilibrium positions have a smaller core-valence bifurcation (CVB) index (< 0.022) and stronger binding energies (> 0.25 eV), showing a clear linear inverse relationship related to H-bond strength. These findings provide an important reference for the comprehensive understanding of H-bonds and its calculation methods.
The influence of 1H-benzo[f]indole (Bd) and its derivatives on room temperature phosphorescence (RTP) has raised great concern since they were found to significantly affect RTP of the extensively studied carbazole (Cz) derivatives. However, the role of Bd itself existing in Cz-based or other doping systems was still unclear. In order to clarify its intrinsic phosphorescent property, Bd was introduced as a guest into different organic matrixes including substituted Cz derivatives and polymers. The phosphorescence located in 560–620 nm was confirmed to be derived from Bd itself, which can be detected whatever Bd was doped in the crystal or amorphous state of Cz derivatives. The suitable energy gap between Cz derivatives and Bd is the key to achieve ultralong RTP of Bd. Additionally, when doped in polymers with plenty of hydrogen bonds, RTP of Bd with lifetime over 280 ms was easily obtained. Among them, Bd@PHEMA (poly(hydroxyethyl methacrylate) exhibited superior phosphorescence, with yellow afterglow lasting for over 2.5 s. Therefore, this work demonstrated that a new organic RTP phosphor, Bd, is discovered, and ultralong RTP of Bd can be achieved not only doped in Cz derivatives but also in polymers as the hosts.
Synthetic antigen-encoding mRNA plays an increasingly significant role in tumor vaccine technology owing to its antigen-specific immune-activation. However, its immune efficacy is challenged by inferior delivery efficiency and demand for suitable adjuvants. Here, we develop a novel mRNA nanovaccine based on a multifunctional nanocapsule, which is a dual-adjuvant formulation composed of cytosine-phosphate-guanine motifs loaded tetrahedral framework nucleic acid (CpG-tFNA) and an immunopeptide murine β-defensin 2 (mDF2β). This mRNA nanovaccine successfully achieves intracellular delivery, antigen expression and presentation of dendritic cells, and proliferation of antigen-specific T cells. In a tumor prophylactic vaccination model, it exerts an excellent inhibitory effect on lymphoma occurrence through cellular immunity. This mRNA nanovaccine has promising prophylactic applications in tumors and many other diseases.
Ternary composites of reduced graphene oxide (GR)-CdS-Pd have been successfully synthesized via solvothermal and photodeposition methods for photocatalytic selective conversion of benzyl alcohol (BA) coupled with hydrogen (H2) production, which exhibit significantly improved photoactivity and selectivity than bare CdS. Mechanistic studies unveil that the cooperative effect of the close interface contact and matched energy level alignment between electrical conducting GR nanosheets (NSs) and CdS nanoparticles (NPs) in GR-CdS-Pd composite not only benefits the separation and transfer of photogenerated carriers but also improves the photocorrosion resistance of CdS. The photodeposited Pd NPs further promote the photogenerated charge separation and accelerate the formation of intermediate products (α-hydroxybenzyl radicals), thereby contributing to enhanced conversion of BA. This work would facilitate the rational design of GR as cocatalyst to construct an efficient and stable CdS-based composite photocatalyst for cooperative coupling of fine chemical synthesis and H2 evolution.