查看更多>>摘要：The dissociation of water is the rate-determining step of several energy-relating reactions due to high energy barrier in homolysis of H-O bond.Herein,engineering vacancy-atom ensembles via injecting oxygen vacancy(Vo)into single facet-exposed TiO2-Pd catalyst to form Vo-Pd ensemble is proposed and implemented.The outstanding activity of as-prepared catalyst,1.5-PdTVo,toward water dissociation is established with a turnover frequency of 240 min-1 in ammonia borane hydrolysis at 298 K.Density functional theory simulation suggests that the Vo-Pd ensemble is responsible for the high intrinsic catalytic activity.Water molecules tend to be dissociated on Vo sites and ammonia borane molecules on Pd atoms.Those H atoms from water dissociation on Vo combine with H atoms from ammonia borane on Pd atoms to generate H2.This insights into engineering vacancy-atom ensembles catalysis provide a new avenue to design catalytic materials for important energy chemical reactions.
查看更多>>摘要：Fluorinated electrolytes possess good antioxidant capacity that provides high compatibility to high-voltage cathode and flame retardance;thus,they are considered as a promising solution for advanced lithium-ion batteries carrying both high-energy density and high safety.Moreover,the fluorinated electrolytes are widely used to form stable electrolyte interphase,due to their chemical reactivity with lithiated graphite or lithium.However,the influence of this reactivity on the thermal safety of batteries is seldom discussed.Herein,we demonstrate that the flame-retardant fluorinated electrolytes help to reduce the flammability,while the lithium-ion batteries with flame-retardant fluorinated electrolytes still undergo thermal runaway and disclose their different thermal runaway pathway from that of battery with conventional electrolyte.The reduction in fluorinated components(e.g.,LiPF6 and fluoroethylene carbonate(FEC))by fully lithiated graphite accounts for a significant heat release during battery thermal runaway.The 13％of total heat is sufficient to trigger the chain reactions during battery thermal runaway.This study deepens the understanding of the thermal runaway mechanism of lithium-ion batteries employing flame-retardant fluorinated electrolytes,providing guidance on the concept of electrolyte design for safer lithium-ion batteries.
查看更多>>摘要：Metal-N2 battery can be applied in both energy storage and electrochemical nitrogen reduction reaction(NRR);however,there has been only extraordinarily little study on metal-N2 battery since its electrochemical reversibility still needs further proofs.And its electrochemical performances also need to be enhanced.Herein,we investigated the discharge-charge reactions between Li anode and N2 cathode via designing an efficient catalyst of nanosized SnO2 particles dispersed on N-doped carbon nanosheets(SnO2@NC)for the Li-N2 battery,with good cyclic stability and a high specific capacity of 0.25 mA h(～500 mA h g-1)at a large current density of 1000 mA g-1.The electrochemical reversibility of both NRR in the discharge process and nitrogen extraction reaction in the charge process for Li-N2 battery is discussed.Time-of-flight secondary ion mass spectrometry results imply that the SnO2@NC can effectively promote the adsorption of N2 and the activation of NRR in the discharge process.Furthermore,ex situ X-ray photoelectron spectroscopy and Fourier transform infrared tests are performed to study the electrochemical reversibility of Li-N2 battery.It can be proved that the formation and decomposition of discharging product Li3N are electrochemical reversible during cycling in our deigned Li-N2 battery system with SnO2@NC catalyst.
查看更多>>摘要：Trifunctional Cu-mesh/Cu2O@FeO nanoarrays heterostructure is designed and fabricated by integrating Cu2O@FeO nanoarrays onto Cu-mesh(CM)via an in situ growth and phase transformation process.It is successfully applied to efficiently mitigate the antibiotic pollution,including degradation of antibiotics,inactivation of antibiotic-resistant bacteria(ARB),and damage of antibiotics resistance genes(ARGs).Under visible-light irradiation,CM/Cu2O@FeO nanoarrays exhibit a superior degradation efficiency on antibiotics(e.g.,up to 99％in 25 min for tetracycline hydrochloride,TC),due to the generated reactive oxygen species(ROS),especially the dominant ·O2-.It can fully inactivate E.coli(HB101)with initial number of～108 CFU mL-1 in 10 min,which is mainly attributed to the synergistic effects of 1D nanostructure,dissolved metal ions,and generated ROS.Meanwhile,it is able to damage ARGs after 180 min of photodegradation,including tetA(vs TC)of 3.3 log10,aphA(vs kanamycin sulfate,KAN)of 3.4 log10,and tnpA(vs ampicillin,AMP)of 4.4 log10,respectively.This work explores a green way for treating antibiotic pollution under visible light.
查看更多>>摘要：Aqueous rechargeable zinc batteries are very attractive for energy storage applications due to their low cost and high safety.However,low operating voltages limit their further development.For the first time,this work proposes a unique approach to increase the voltages of aqueous zinc batteries by using tri-functional metallic bipolar electrode with good electrochemical activity and ultrahigh electronic conductivity,which not only participates in redox reactions,but also functions as an electrical highway for charge transport.Furthermore,bipolar electrode can replace expensive ion selective membrane to separate electrolytes with different pH;thus,redox couples with higher potential in acid condition and Zn/Zn(OH)42-couple with lower potential in alkaline condition can be employed together,leading to high voltages of aqueous zinc batteries.Herein,two types of metallic bipolar electrodes of Cu and Ag are utilized based on three kinds of aqueous zinc batteries:Zn-MnO2,Zn-I2,and Zn-Br2.The voltage of aqueous Zn-MnO2 battery is raised to 1.84 V by employing one Cu bipolar electrode,which shows no capacity attenuation after 3500 cycles.Moreover,the other Ag bipolar electrode can be adopted to successfully construct Zn-I2 and Zn-Br2 batteries exhibiting much higher voltages of 2.44 and 2.67 V,which also show no obvious capacity degradation for 1000 and 800 cycles,representing decent cycle stability.Since bipolar electrode can be applied in a large family of aqueous batteries,this work offers an elaborate high-voltage concept based on tri-functional metallic bipolar electrode as a model system to open a door to explore high-voltage aqueous batteries.
查看更多>>摘要：With the increasing interest in highly concentrated electrolyte systems,correct determination of the cation transference number is important.Pulsed-field gradient NMR technique,which measures self-diffusion coefficients,is often applied on liquid electrolytes because of the wide accessibility and simple sample preparation.However,since the assumptions of this technique,that is,complete salt dissociation,all ions participating in motion,and all of them moving independently,no longer hold true in concentrated solutions,the transference numbers,thus obtained are often over-estimated.In the present work,impedance spectroscopy at a frequency range of 1 MHz to 0.1 mHz was used to examine the concentration effect on lithium-ion transference number under anion-blocking conditions TLi+abcfor two electrolytes:lithium bis(fluorosulfonyl)imide(LiFSI)in sulfolane(SL)and lithium bis(trifluorosulfonyl)imide(LiTFSI)in tetraglyme(G4).The TLi+abcof the former was almost an order of magnitude higher than that of the latter.It also appeared to increase with increasing concentration while the latter followed an opposite trend.The faster Li+transport in the SL system is attributed to the formation of a liquid structure consisting of extended chains/bridges of SL molecules and the anions,which facilitate a cation-hopping/ligand-exchanged-typed diffusion mechanism by partially decoupling the cations from the anions and solvent molecules.The G4 system,in contrast,is dominated by the formation of long-lived,stable[Li(G4)]+solvation cages that results in a sluggish Li+transport.The difference between the two transport mechanisms is discussed via comparison of the bulk ionic conductivity,viscosity,ion self-diffusion coefficients,and the Onsager transport coefficients.
查看更多>>摘要：Developing high-performance catalysts using traditional trial-and-error methods is generally time consuming and inefficient.Here,by combining machine learning techniques and first-principle calculations,we are able to discover novel graphene-supported single-atom catalysts for nitrogen reduction reaction in a rapid way.Successfully,45 promising catalysts with highly efficient catalytic performance are screened out from 1626 candidates.Furthermore,based on the optimal feature sets,new catalytic descriptors are constructed via symbolic regression,which can be directly used to predict single-atom catalysts with good accuracy and good generalizability.This study not only provides dozens of promising catalysts and new descriptors for nitrogen reduction reaction but also offers a potential way for rapid screening of new electrocatalysts.
查看更多>>摘要：Thermal energy is abundantly available in our daily life and industrial production,and especially,low-grade heat is often regarded as a byproduct.Collecting and utilizing this ignored energy by low-cost and simple technologies may become a smart countermeasure to relieve the energy crisis.Here,a unique device has been demonstrated to achieve high value-added conversion of low-grade heat by introducing redox-active organic alizarin(AZ)onto N-doped hollow carbon nanofibers(N-HCNF)surface.As-prepared N-HCNF/AZ can deliver a high specific capacitance of 514.3 F g-1(at 1 A g-1)and an outstanding rate capability of 60.3％even at 50 A g1.Meanwhile,the assembled symmetric proton capacitor can deliver a high energy density of 28.0 Wh kg-1 at 350.0 W kg-1 and a maximum power density of 35.0 kW kg-1 at 17.0 Wh kg-1.Significantly,the thermally chargeable proton capacitors can attain a surprisingly high Seebeck coefficient of 15.3 mV K-1 and a power factor of 6.02 μW g-1.Taking advantage of such high performance,a satisfying open-circuit voltage of 481.0 mV with a temperature difference of 54 K is achieved.This research provides new insights into construction of high value-added energy systems requiring high electrochemical performances.
查看更多>>摘要：The defect-free structure of Mo-based materials is a"double-edged sword",which endows the material with excellent stability,but limits its chemical versatility and application in electrochemical hydrogen evolution reaction(HER).Carbon doping engineering is an attractive strategy to effectively improve the performance of Mo-based catalyst and maintain their stability.Herein,we report a cross-linked porous carbon-doped MoO2(C-MoO2)-based catalyst Ru/C-MoO2 for electrochemical HER,which is prepared by the convenient redox solid-phase reaction(SPR)of porous RuO2/Mo2C composite precursor.Theoretical studies reveal that due to the presence of carbon atoms,the electronic structure of C-MoO2 has been properly adjusted,and the loaded small Ru nanoparticles provide a fast water dissociation rate and moderate H adsorption strength.In electrochemical studies under a pH-universal environment,Ru/C-MoO2 electrocatalyst exhibits a low overpotential at a current density of 10 mA cm-2 and has a low Tafel slope.Meanwhile,Ru/C-MoO2 has excellent stability for more than 100 h at an initial current density of 100 mA cm-2.
查看更多>>摘要：Recyclability and self-healing are two most critical factors in developing sustainable polymers to deal with environmental pollution and resource waste.In this work,a dynamic cross-linked polyimide insulation film with full closed-loop recyclability is successfully prepared,which also possesses good self-healing ability after being mechanical/electrical damaged depending on the Schiff base dynamic covalent bonds.The recycled and self-healed polyimide film still maintain its good tensile strength(σt)＞60 MPa with Young's modulus(E)＞4 GPa,high thermal stability with glass transition temperature(Tg)＞220 ℃,and outstanding insulation property with breakdown strength(E0)＞358 kV mm-1,making it a very promising low energy consumption and high temperature resistant insulation material.The strategy of using Schiff base dynamic covalent bonds for reversible repairing the structure of high Tg polyimides promotes the wider application of such sustainable and recyclable material in the field of electrical power and micro-electronics.
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