查看更多>>摘要：Poly(ethylene oxide)(PEO)and Li6.75La3Zr1.75Tao.25012(LLZTO)-based composite polymer electrolytes(CPEs)are considered one of the most promising solid electrolyte systems.However,agglomeration of LLZTO within PEO and lack of Li+channels result in poor electrochemical properties.Herein,a functional supramolecular combination(CD-TFSI)consisting of active β-cyclodextrin(CD)supramolecular with self-assembled LiTFSI salt is selected as an interface modifier to coat LLZTO fillers.Benefiting from vast H-bonds formed between β-CD and PEO matrix and/or LLZTO,homogeneous dispersion and tight interface contact are obtained.Moreover,6Li NMR spectra confirm a new Li+transmission pathway from PEO matrix to LLZTO ceramic then to PEO matrix in the as-prepared PEO/LLZTO@CD-TFSI CPEs due to the typical cavity structure of β-CD.As a proof,the conductivity is increased from 5.3 × 10-4 S cm-1 to 8.7 × 10-4 S cm-1 at 60 ℃,the Li+transference number is enhanced from 0.38 to 0.48,and the electrochemical stability window is extended to 5.1 V versus Li/Li+.Li‖ LiFePO4 CR2032 coin full cells and pouch cells prove the practical application of the as-prepared PEO/LLZTO@CD-TFSI CPEs.This work offers a new strategy of interface modifying LLZTO fillers with functional supramolecular combination to optimize PEO/LLZTO CPEs for solid lithium batteries.
查看更多>>摘要：Oxygen vacancies enable modulating surface reconstruction of transition metal oxides containing metal-oxygen polyhedrons into metallic oxyhydroxide for oxygen evolution reaction(OER),while revealing reconstructing mechanism is stuck by the requirement to precisely control exact sites of these vacancies.Herein,oxygen vacancies are localized only within MoO4 tetrahedrons rather than CoO6 octahedrons in CoMoO4 catalyst,guaranteeing coherent reconstruction of CoO6 octahedrons into pure CoOOH with tunable activities for OER.Meanwhile,distorted tetrahedron accelerates the dissolution of Mo atoms into alkaline electrolyte,triggering spontaneous transition of partial CoMoO4 into Co(OH)2.CoO6 octahedrons in both CoMoO4 and Co(OH)2 can transform pure CoOOH completely at lower potential,resulting in excess intrinsic activity whose summit is identified by overpotential at 10 mA cm-2 with 22.9％reduction and Tafel slope with 65.3％reduction.Well-defined manipulation over the distorted polyhedrons offers one versatile knob to precisely modulate electronic structure of oxide catalysts with outstanding OER performance.
查看更多>>摘要：We report the dielectric constant of 1 M LiPF6 in EC:EMC 3∶7 w/w(ethylene carbonate/ethyl methyl carbonate)in addition to neat EC:EMC 3∶7 w/w.Using three Debye relaxations,the static permittivity value,or dielectric constant,is extrapolated to 18.5,which is compared to 18.7 for the neat solvent mixture.The EC solvent is found to strongly coordinate with the Li+cations of the salt,which results in a loss of dielectric contribution to the electrolyte.However,the small amplitude and large uncertainty in relaxation frequency for EMC cloud definitive identification of the Li+solvation shell.Importantly,the loss of the free EC permittivity contribution due to Li+solvation is almost completely balanced by the positive contribution of the associated LiPF6 salt,demonstrating that a significant quantity of dipolar ion pairs exists in 1 M LiPF6 in EC:EMC 3∶7.
查看更多>>摘要：CO2 electrochemical reduction reaction(CO2RR)to formate is a hopeful pathway for reducing CO2 and producing high-value chemicals,which needs highly selective catalysts with ultra-broad potential windows to meet the industrial demands.Herein,the nanorod-like bimetallic ln2O3/Bi2O3 catalysts were successfully synthesized by pyrolysis of bimetallic InBi-MOF precursors.The abundant oxygen vacancies generated from the lattice mismatch of Bi2O3 and ln2O3 reduced the activation energy of CO2 to *CO2·-and improved the selectivity of *CO2·-to formate simultaneously.Meanwhile,the carbon skeleton derived from the pyrolysis of organic framework of InBi-MOF provided a conductive network to accelerate the electrons transmission.The catalyst exhibited an ultra-broad applied potential window of 1200 mV(from-0.4 to-1.6 V vs RHE),relativistic high Faradaic efficiency of formate(99.92％)and satisfactory stability after 30 h.The in situ FT-IR experiment and DFT calculation verified that the abundant oxygen vacancies on the surface of catalysts can easily absorb CO2 molecules,and oxygen vacancy path is dominant pathway.This work provides a convenient method to construct high-performance bimetallic catalysts for the industrial application of CO2RR.
查看更多>>摘要：Piezoelectric ceramic and polymeric separators have been proposed to effectively regulate Li deposition and suppress dendrite growth,but such separators still fail to satisfactorily support durable operation of lithium metal batteries owing to the fragile ceramic layer or low-piezoelectricity polymer as employed.Herein,by combining PVDF-HFP and ferroelectric BaTiO3,we develop a homogeneous,single-layer composite separator with strong piezoelectric effects to inhibit dendrite growth while maintaining high mechanical strength.As squeezed by local protrusion,the polarized PVDF-HFP/BaTiO3 composite separator generates a local voltage to suppress the local-intensified electric field and further deconcentrate regional lithium-ion flux to retard lithium deposition on the protrusion,hence enabling a smoother and more compact lithium deposition morphology than the unpoled composite separator and the pure PVDF-HFP separator,especially at high rates.Remarkably,the homogeneous incorporation of BaTiO3 highly improves the piezoelectric performances of the separator with residual polarization of 0.086 pC cm-2 after polarization treatment,four times that of the pure PVDF-HFP separator,and simultaneously increases the transference number of lithium-ion from 0.45 to 0.57.Beneficial from the prominent piezoelectric mechanism,the polarized PVDF-HFP/BaTiO3 composite separator enables stable cyclic performances of Li||LiFePO4 cells for 400 cycles at 2 C(1 C=170 mA g-1)with a capacity retention above 99％,and for 600 cycles at 5 C with a capacity retention over 85％.
查看更多>>摘要：Ultraviolet position-sensitive detectors(PSDs)are expected to undergo harsh environments,such as high temperatures,for a wide variety of applications in military,civilian,and aerospace.However,no report on relevant PSDs operating at high temperatures can be found up to now.Herein,we design a new 2D/3D graphitic carbon nitride(g-C3N4)/gallium nitride(GaN)hybrid heterojunction to construct the ultraviolet high-temperature-resistant PSD.The g-C3N4/GaN PSD exhibits a high position sensitivity of 355 mV mm-1,a rise/fall response time of 1.7/2.3 ms,and a nonlinearity of 0.5％at room temperature.The ultralow formation energy of-0.917 eV atom-1 has been obtained via the thermodynamic phase stability calculations,which endows g-C3N4 with robust stability against heat.By merits of the strong built-in electric field of the 2D/3D hybrid heterojunction and robust thermo-stability of g-C3N4,the g-C3N4/GaN PSD delivers an excellent position sensitivity and angle detection nonlinearity of 315 mV mm-1 and 1.4％,respectively,with high repeatability at a high temperature up to 700 K,outperforming most of the other counterparts and even commercial silicon-based devices.This work unveils the high-temperature PSD,and pioneers a new path to constructing g-C3N4-based harsh-environment-tolerant optoelectronic devices.
查看更多>>摘要：In situ surface-enhanced Raman scattering(SERS)is a widely used operando analytical technique,while facing numerous complex factors in applications under aqueous environment,such as low detection sensitivity,poor anti-interference capability,etc.,resulting in unreliable detectability.To address these issues,herein a new hydrophobic SERS strategy has been attempted.By comprehensively designing and researching a SERS-active structure of superhydrophobic ZnO/Ag nanowires,we demonstrate that hydrophobicity can not only draw analytes from water onto substrate,but also adjust"hottest spot"from the bottom of the nanowires to the top.As a result,the structure can simultaneously concentrate the dispersed molecules in water and the enhanced electric field in structure into a same zone,while perfecting its own anti-interference ability.The underwater in situ analytical enhancement factor of this platform is as high as 1.67 × 1011,and the operando limited of detection for metronidazole(MNZ)reaches to 10-9 M.Most importantly,we also successfully generalized this structure to various real in situ detection scenarios,including on-site detection of MNZ in corrosive urine,real-time warning of wrong dose of MNZ during intravenous therapy,in situ monitoring of MNZ in flowing wastewater with particulate interference,etc.,demonstrating the great application potential of this hydrophobic platform.This work realizes a synergistic promotion for in situ SERS performance under aqueous environment,and also provides a novel view for improving other in situ analytical techniques.
查看更多>>摘要：Zero-dimensional(0D)hybrid metal halides,which consist of organic cations and isolated inorganic metal halide anions,have emerged as phosphors with efficient broadband emissions.However,these materials generally have too wide bandgaps and thus cannot be excited by blue light,which hinders their applications for efficient white light-emitting diodes(WLEDs).The key to achieving a blue-light-excitable 0D hybrid metal halide phosphor is to reduce the fundamental bandgap by rational chemical design.In this work,we report two designed hybrid copper(I)iodides,(Ph3MeP)2Cu4I6 and(Cy3MeP)2Cu4I6,as blue-light-excitable yellow phosphors with ultrabroadband emission.In these compounds,the[Cu4I6]2-anion forms an I6 octahedron centered on a cationic Cu4 tetrahedron.The strong cation-cation bonding within the unique cationic Cu4 tetrahedra enables significantly lowered conduction band minimums and thus narrowed bandgaps,as compared to other reported hybrid copper(I)iodides.The ultrabroadband emission is attributed to the coexistence of free and self-trapped excitons.The WLED using the[Cu4I6]2-anion-based single phosphor shows warm white light emission,with a high luminous efficiency of 65 Im W-1 and a high color rendering index of 88.This work provides strategies to design narrow-bandgap 0D hybrid metal halides and presents two first examples of blue-light-excitable 0D hybrid metal halide phosphors for efficient WLEDs.
查看更多>>摘要：Herein,we demonstrate the synthesis of bifunctional nickel cobalt selenide@nickel telluride(NixCo12.xSe@NiTe)core-shell heterostructures via an electrodeposition approach for overall urea electrolysis and supercapacitors.The 3D vertically orientated NiTe dendritic frameworks induce the homogeneous nucleation of 2D NixCo12.xSe nanosheet arrays along similar crystal directions and bring a strong interfacial binding between the integrated active components.In particular,the optimized Ni6Co6Se@NiTe with an interface coupling effect works in concert to tune the intrinsic activity.It only needs a low overpotential of 1.33 V to yield a current density of 10 mA cm-2 for alkaline urea electrolysis.Meanwhile,the full urea catalysis driven only by Ni6Co6Se@NiTe achieves 10 mA cm-2 at a potential of 1.38 V and can approach a constant level of the current response for 40 h.Besides,the integrated Ni6Co6Se@NiTe electrode delivers an enhanced specific capacity(223 mA h g-1 at 1 A g-1)with a high cycling stability.Consequently,a hybrid asymmetric supercapacitor(HASC)device based on Ni6Co6Se@NiTe exhibits a favorable rate capability and reaches a high energy density of 67.7 Wh kg-1 and a power density of 724.8 W kg-1 with an exceptional capacity retention of 92.4％after sequential 12 000 cycles at 5 A g-1.
查看更多>>摘要：In this work,we open an avenue toward rational design of potential efficient catalysts for sustainable ammonia synthesis through composition engineering strategy by exploiting the synergistic effects among the active sites as exemplified by diatomic metals anchored graphdiyne via the combination of hierarchical high-throughput screening,first-principles calculations,and molecular dynamics simulations.Totally 43 highly efficient catalysts feature ultralow onset potentials(|Uonset|≤ 0.40 V)with Rh-Hf and Rh-Ta showing negligible onset potentials of 0 and-0.04 V,respectively.Extremely high catalytic activities of Rh-Hf and Rh-Ta can be ascribed to the synergistic effects.When forming heteronuclears,the combinations of relatively weak(such as Rh)and relatively strong(such as Hf or Ta)components usually lead to the optimal strengths of adsorption Gibbs free energies of reaction intermediates.The origin can be ascribed to the mediate d-band centers of Rh-Hf and Rh-Ta,which lead to the optimal adsorption strengths of intermediates,thereby bringing the high catalytic activities.Our work provides a new and general strategy toward the architecture of highly efficient catalysts not only for electrocatalytic nitrogen reduction reaction(eNRR)but also for other important reactions.We expect that our work will boost both experimental and theoretical efforts in this direction.
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