查看更多>>摘要：Fe-N-C catalysts are widely considered as promising non-precious-metal candidates for electrocatalytic oxygen reduction reaction(ORR).Yet despite their high catalytic activity through rational modulation,challenges remain in their low site density and unsatisfactory mass transfer structure.Herein,we present a structural engineering approach employing a soft-template coating strategy to fabricate a hollow and hierarchically porous N-doped carbon framework anchored with atomically dispersed Fe sites(FeNC-h)as an efficient ORR catalyst.The combination of hierarchical porosity and high exterior surface area is proven crucial for exposing more active sites,which gives rise to a remarkable ORR performance with a half-wave potential of 0.902 V in 0.1 M KOH and 0.814 V in 0.1 M HClO4,significantly outperforming its counterpart with solid structure and dominance of micropores(FeNC-s).The mass transfer property is revealed by in-situ electrochemical impedance spectroscopy(EIS)measurement.The distribution of relaxation time(DRT)analysis is further introduced to deconvolve the kinetic and mass transport pro-cesses,which demonstrates an alleviated mass transport resistance for FeNC-h,validating the effective-ness of structural engineering.This work not only provides an effective structural engineering approach but also contributes to the comprehensive mass transfer evaluation on advanced electrocatalyst for energy conversion applications.
查看更多>>摘要：The interfacial nonradiative recombination loss caused by the deep traps and mismatched band align-ment restrained the commercial viability of perovskite solar cells(PSCs).Herein,we have constructed fer-rocene carboxylic acid(FcA)and octafluoropentyl-ferrocenyl-carboxylate(OFFcA)interstitial conductive mediums to modulate the integral heterointerface properties and the photovoltaic performances of PSCs.By comparing the passivation strengths of the two molecules,we found that the synergistic effects among Fc/Fc+redox shuttle,C=O group,and F substituents realize the optimal elimination of interfacial trap sources.Electron-withdrawing F groups reinforce the capacity of the Fc/Fc+redox shuttle for the healing of metallic Pb defects and provide extensive anchoring sites to stabilize the organic components.Additionally,the homogeneity of the OFFcA layer as well as the humidity stability of perovskite film are facilitated through the introduction of F substituents,which reduce the contact resistance and improve the interfacial charge transfer.The champion OFFcA-modified device delivers an exceptional PCE of 23.62％,exceeding those of the control(PCE=22.32％)and FcA-modified(PCE=23.06％)devices.Moreover,the unencapsulated OFFcA-modified device retains 82.7％of the primary efficiency at 60％RH for more than 50 d and only loses less than 10％of the primary efficiency when stored in a glove box for more than 2000 h.
查看更多>>摘要：Phenyl-C61-butyric acid methyl ester(PCBM)serves as a common electron transport layer(ETL)in inverted p-i-n structure perovskite solar cells(IPSCs),yet energy barriers and insufficient passivation at the PCBM-perovskite interface hinder device effectiveness and durability.In this study,we present a series of novel Fullerene Phenylacid Ester Derivatives(FPEDs:FPP,FTPP,FDPP)incorporated into PCBM.Our investigations illustrate that FPEDs effectively act to passivate the perovskite surface by form-ing robust interactions with uncoordinated Pb2+ions via the phosphine oxide groups present in their molecular structures,thereby enhancing the stability of the devices.Moreover,these additives elevate the energy level of the lowest unoccupied molecular orbital(LUMO)of ETL,diminish the electron injec-tion barrier,and enhance the efficiency of interlayer electron transport.Incorporating FPEDs enhances ETL coverage on the perovskite layer,reducing leakage current significantly.Notably,Devices with PCBM/FTPP achieved a peak PCE of 23.62％and showed superior stability,maintaining 96.8％of the initial PCE after 500 h,while control devices retained merely 80.7％over the same period.
查看更多>>摘要：Two-dimensional transition metal carbides(MXenes)have been demonstrated to be promising supports for single-atom catalysts(SACs)to enable efficient oxygen evolution reaction(OER).However,the rational design of MXene-based SACs depends on an experimental trial-and-error approach.A theoretical guidance principle is highly expected for the efficient evaluation of MXene-based SACs.Herein,high-throughput screening was performed through first-principles calculations and machine learning tech-niques.Ti3C2(OH)x,V3C2(OH)x,Zr3C2(OH)x,Nb3C2(OH)x,Hf3C2(OH)x,Ta3C2(OH)x,and W3C2(OH)x were screened out based on their excellent stability.Zn,Pd,Ag,Cd,Au,and Hg were proposed to be promising single atoms anchored in MXenes based on cohesive energy analysis.Hf3C2(OH)x with a Pd single atom delivers a theoretical overpotential of 81 mV.Both moderate electron-deficient state and high covalency of metal-carbon bonds were critical features for the high OER reactivity.This principle is expected to be a promising approach to the rational design of OER catalysts for metal-air batteries,fuel cells,and other OER-based energy storage devices.
查看更多>>摘要：Current aqueous battery electrolytes,including conventional hydrogel electrolytes,exhibit unsatisfactory water retention capabilities.The sustained water loss will lead to subsequent polarization and increased internal resistance,ultimately resulting in battery failure.Herein,a double network(DN)organohydrogel electrolyte based on dimethyl sulfoxide(DMSO)/H2O binary solvent was proposed.Through directionally reconstructing hydrogen bonds and reducing active H2O molecules,the water retention ability and cath-ode/anode interfaces were synergistic enhanced.As a result,the synthesized DN organohydrogel demon-strates exceptional water retention capabilities,retaining approximately 75％of its original weight even after the exposure to air for 20 days.The Zn||MnO2 battery delivers an outstanding specific capacity of 275 mA h g-1 at 1 C,impressive rate performance with 85 mA h g-1 at 30 C,and excellent cyclic stability(95％retention after 6000 cycles at 5 C).Zn||Zn symmetric battery can cycle more than 5000 h at 1 mA cm-2 and 1 mA h cm-2 without short circuiting.This study will encourage the further development of functional organohydrogel electrolytes for advanced energy storage devices.
查看更多>>摘要：Silicon is considered to be one of the most promising anode materials for lithium-ion batteries(LIBs),but its application is limited by the large volume expansion during alloying and dealloying.The constructing of a high-performance solid electrolyte interface(SEI)film on the surface of the anode material is consid-ered to be one of the effective strategies to mitigate volume expansion of silicon-based anode.In this study,an intermittent discharge strategy which helps to improve the utilization efficiency of electrolyte additive of lithium difluorobisoxalate phosphate(LiDFBOP)is proposed to construct a highly conductive and dense SEI film.The results of electrochemical and physical characterization and theoretical calcula-tions show that the intermittent discharge in the voltage range from open circuit voltage(OCV)to 1.8 V facilitates the diffusion of the soluble products,creates the conditions for the repeated direct contact between Si@C anode and LiDFBOP additive,increases the decomposition of LiDFBOP additive,and thus produces a uniform,dense and inorganics-rich(Li2C2O4,LiF and LixPOyFz)SEI film.Subsequently,this SEI film helps to ensure the even intercalation/de-intercalation of Li+in the SEI film and the homogeneous diffusion of Li+inside the Si particles,decreasing the internal stresses and anisotropic phase transitions,maintaining the integrity of Si particles,inhibiting the volume expansion and thus improving the electro-chemical performance of cells.This study not only improves the utilization efficiency of expensive addi-tives through a simply and low-cost method,but also enriches the strategy to improve the electrochemical performance of Si@C anode through interfacial engineering.
查看更多>>摘要：Sustainable nitrogen fixation driven by renewable energy sources under mild conditions has been widely sought to replace the industrial Haber-Bosch process.The fixation of nitrogen in the form of NOx-and NH4 into aqueous solutions using electricity-driven gas-liquid discharge plasma is considered a promising prescription.In this paper,a scalable bubble discharge excited by nanosecond pulse power is employed for nitrogen fixation in the liquid phase.The nitrogen fixation performance and the mechanisms are ana-lyzed by varying the power supply parameters,working gas flow rate and composition.The results show that an increase in voltage and frequency can result in an enhanced NO3 yield.Increases in the gas flow rate can result in inadequate activation of the working gas,which together with more inefficient mass transfer efficiencies can reduce the yield.The addition of O2 effectively elevates NO3-production while simultaneously inhibiting NH4+production.The addition of H2O vapor increases the production of OH and H,thereby promoting the generation of reactive nitrogen and enhancing the yield of nitrogen fixa-tion.However,the excessive addition of O2 and H2O vapor results in negative effect on the yield of nitro-gen fixation,due to the significant weakening of the discharge intensity.The optimal nitrogen fixation yield was up to 16.5 μmol/min,while the optimal energy consumption was approximately 21.3 MJ/mol in this study.Finally,the mechanism related to nitrogen fixation is discussed through the optical emission spectral(OES)information in conjunction with the simulation of energy loss paths in the plasma by BOLSIG+.The work advances knowledge of the effect of parameter variations on nitrogen fixation by gas-liquid discharge for higher yield and energy production.
查看更多>>摘要：Additives in the electrolytes of Li-S batteries aim to increase overall capacity,improve Li+ion conductiv-ity,enhance cyclability,and mitigate the shuttle effect,which is one of the major issues of this system.Here,the use of water as an additive in the commonly used electrolyte,1.0 M LiTFSI/1.0％(w/w)LiN03 and a 1∶1 mixture of 1,3-dioxolane(DOL)and 1,2-dimethoxyethane(DME)was investigated.We used C02Mn0.5Al0.5O4(CMA)as an electrocatalyst anchored on an activated carbon(AC)electrode with added sulfur via a melt-diffusion process.The structural analysis of CMA via Rietveld refinement showed inter-atomic spaces that can promote ionic conductivity,facilitating Li+ion migration.Electrochemical tests determined 1600 ppm as the optimal water concentration,significantly reducing the shuttle effect.Post-mortem XPS analysis focused on the lithium metal anode revealed the formation of Li2O layers in dry samples and LiOH in wet samples.Better capacity was observed in wet samples,which can be attrib-uted to the superior ionic conductivity of LiOH at the electrode/electrolyte interface,surpassing that of Li2O by 12 times.Finally,Operando FTIR experiments provided real-time insights into electrolyte degra-dation and SEI formation,elucidating the activity mechanisms of water and Li2CO3 over the cycles.This work presents results that could aid future advancements in Li-S battery technology,offering possibilities to mitigate its challenges with inexpensive and scalable additives.
Mengfang LiangXiaodong ShaoJi Yoon ChoiYoung Dok Kim...
714-720页
查看更多>>摘要：Utilizing sunlight to convert CO2 into chemical fuels could address the greenhouse effect and fossil fuel crisis.Heterojunction structure catalysts with oxygen vacancy are attractive in the field of photocatalytic CO2 conversion.Herein,a modified TiO2/In2O3(R-P25/In2O3-x)type Ⅱ heterojunction composite with oxy-gen vacancies is designed for photocatalytic CO2 reduction,which exhibits excellent CO2 reduction activ-ity,with a C2 selectivity of 56.66％(in terms of Reiectron).In situ Fourier-transform infrared spectroscopy(DRIFTS)and time-resolved photoluminescence(TR-PL)spectroscopy are used to reveal the intermediate formation of the photocatalytic mechanism and photogenerated electron lifetime,respectively.The experimental characterizations reveal that the R-P25/In2O3-x composite shows a remarkable behavior for coupling C-C bonds.Besides,efficient charge separation contributes to the improved CO2 conversion performance of photocatalysts.This work introduces a type Ⅱ heterojunction composite photocatalyst,which promotes understanding the CO2 reduction mechanisms on heterojunction composites and is valu-able for the development of photocatalysts.
查看更多>>摘要：In this work,nickel foam supported CeO2-modified CoBDC(BDC stands for terephthalic acid linker)metal-organic frameworks(NF/CoBDC@CeO2)are prepared by hydrothermal and subsequent impregna-tion methods,which can be further transformed to NF/CoOOH@CeO2 by reconstruction during the elec-trocatalytic test.The obtained NF/CoOOH@CeO2 exhibits excellent performance in electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF)because the introduction of CeO2 can optimize the elec-tronic structure of the heterointerface and accelerate the accumulation of*OH.It requires only a potential of 1.290 VRHE to provide a current density of 50 mA cm-2 in 1.0 M KOH+50 mM HMF,which is 222 mV lower than that required in 1.0 M KOH(1.512 VRHE).In addition,density-functional theory calculation results demonstrate that CeO2 biases the electrons to the CoOOH side at the heterointerface and pro-motes the adsorption of*OH and*HMF on the catalyst surface,which lower the reaction energy barrier and facilitate the electrocatalytic oxidation process.
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