查看更多>>摘要：The electrochemical methanol oxidation is a crucial reaction in the conversion of renewable energy.To enable the widespread adoption of direct methanol fuel cells(DMFCs),it is essential to create and engi-neer catalysts that are both highly effective and robust for conducting the methanol oxidation reaction(MOR).In this work,trimetallic PtCoRu electrocatalysts on nitrogen-doped carbon and multi-wall carbon nanotubes(PtCoRu@NC/MWCNTs)were prepared through a two-pot synthetic strategy.The acceleration of CO oxidation to CO2 and the blocking of CO reduction on adjacent Pt active sites were attributed to the crucial role played by cobalt atoms in the as-prepared electrocatalysts.The precise control of Co atoms loading was achieved through precursor stoichiometry.Various physicochemical techniques were employed to analyze the morphology,element composition,and electronic state of the catalyst.Electrochemical investigations and theoretical calculations confirmed that the Pt1Co3Ru1@NC/MWCNTs exhibit excellent electrocatalytic performance and durability for the process of MOR.The enhanced MOR activity can be attributed to the synergistic effect between the multiple elements resulting from precisely controlled Co loading content on surface of the electrocatalyst,which facilitates efficient charge transfer.This interaction between the multiple components also modifies the electronic structures of active sites,thereby promoting the conversion of intermediates and accelerating the MOR process.Thus,achieving precise control over Co loading in PtCoRu@NC/MWCNTs would enable the development of high-performance catalysts for DMFCs.
查看更多>>摘要：To achieve high energy density in lithium batteries,the construction of lithium-ion/metal hybrid anodes is a promising strategy.In particular,because of the anisotropy of graphite,hybrid anode formed by gra-phite/Li metal has low transport kinetics and is easy to causes the growth of lithium dendrites and accu-mulation of dead Li,which seriously affects the cycle life of batteries and even causes safety problems.Here,by comparing graphite with two types of hard carbon,it was found that hybrid anode formed by hard carbon and lithium metal,possessing more disordered mesoporous structure and lithophilic groups,presents better performance.Results indicate that the mesoporous structure provides abundant active site and storage space for dead lithium.With the synergistic effect of this structure and lithophilic func-tional groups(-COOH),the reversibility of hard carbon/lithium metal hybrid anode is maintained,pro-moting uniform deposition of lithium metal and alleviating formation of lithium dendrites.The hybrid anode maintains a 99.5％Coulombic efficiency(CE)after 260 cycles at a specific capacity of 500 mAh/g.This work provides new insights into the hybrid anodes formed by carbon-based materials and lithium metal with high specific energy and fast charging ability.
查看更多>>摘要：The shuttle effect of lithium polysulfides(LiPSs)and uncontrollable lithium dendrite growth seriously hinder the practical application of lithium-sulfur(Li-S)batteries.To simultaneously address such issues,monodispersed NbN quantum dots anchored on nitrogen-doped hollow carbon nanorods(NbN@NHCR)are elaborately developed as efficient LiPSs immobilizer and Li stabilizer for high-performance Li-S full batteries.Density functional theory(DFT)calculations and experimental characterizations demonstrate that the sulfiphilic and lithiophilic NbN@NHCR hybrid can not only efficiently immobilize the soluble LiPSs and facilitate diffusion-conversion kinetics for alleviating the shuttling effect,but also homogenize the distribution of Li+ions and regulate uniform Li deposition for suppressing Li-dendrite growth.As a result,the assembled Li-S full batteries(NbN@NHCR-S‖NbN@NHCR-Li)deliver excellent long-term cycling stability with a low decay rate of 0.031％per cycle over 1000 cycles at high rate of 2 C.Even at a high S loading of 5.8 mg cm-2 and a low electrolyte/sulfur ratio of 5.2 μL mg-1,a large areal capacity of 6.2 mA h cm-2 can be achieved in Li-S pouch cell at 0.1 C.This study provides a new perspective via designing a dual-functional sulfiphilic and lithiophilic hybrid to address serious issues of the shuttle effect of S cathode and dendrite growth of Li anode.
查看更多>>摘要：It is a challenge to coordinate carrier-kinetics performance and the redox capacity of photogenerated charges synchronously at the atomic level for boosting photocatalytic activity.Herein,the atomic Ni was introduced into the lattice of hexagonal ZnIn2S4 nanosheets(Ni/ZnIn2S4)via directional-substituting Zn atom with the facile hydrothermal method.The electronic structure calculations indicate that the introduction of Ni atom effectively extracts more electrons and acts as active site for subsequent reduction reaction.Besides the optimized light absorption range,the elevation of Ef and ECB endows Ni/ZnIn2S4 photocatalyst with the increased electron concentration and the enhanced reduction ability for surface reaction.Moreover,ultrafast transient absorption spectroscopy,as well as a series of electro-chemical tests,demonstrates that Ni/ZnIn2S4 possesses 2.15 times longer lifetime of the excited charge carriers and an order of magnitude increase for carrier mobility and separation efficiency compared with pristine ZnIn2S4.These efficient kinetics performances of charge carriers and enhanced redox capacity synergistically boost photocatalytic activity,in which a 3-times higher conversion efficiency of nitroben-zene reduction was achieved upon Ni/ZnIn2S4.Our study not only provides in-depth insights into the effect of atomic directional-substitution on the kinetic behavior of photogenerated charges,but also opens an avenue to the synchronous optimization of redox capacity and carrier-kinetics performance for efficient solar energy conversion.
查看更多>>摘要：The function of solid electrolytes and the composition of solid electrolyte interphase(SEI)are highly sig-nificant for inhibiting the growth of Li dendrites.Herein,we report an in-situ interfacial passivation com-bined with self-adaptability strategy to reinforce Li0.33La0.557TiO3(LLTO)-based solid-state batteries.Specifically,a functional SEI enriched with LiF/Li3PO4 is formed by in-situ electrochemical conversion,which is greatly beneficial to improving interface compatibility and enhancing ion transport.While the polarized dielectric BaTiO3-polyamic acid(BTO-PAA,BP)film greatly improves the Li-ion transport kinet-ics and homogenizes the Li deposition.As expected,the resulting electrolyte offers considerable ionic conductivity at room temperature(4.3 × 10-4 S cm-1)and appreciable electrochemical decomposition voltage(5.23 V)after electrochemical passivation.For Li-LiFePO4 batteries,it shows a high specific capac-ity of 153 mA h g-1 at 0.2 C after 100 cycles and a long-term durability of 115 mA h g-1 at 1.0 C after 800 cycles.Additionally,a stable Li plating/stripping can be achieved for more than 900 h at 0.5 mA cm-2.The stabilization mechanisms are elucidated by ex-situ XRD,ex-situ XPS,and ex-situ FTIR techniques,and the corresponding results reveal that the interfacial passivation combined with polarization effect is an effec-tive strategy for improving the electrochemical performance.The present study provides a deeper insight into the dynamic adjustment of electrode-electrolyte interfacial for solid-state lithium batteries.
查看更多>>摘要：Functional materials may change color by heat and electricity separately or simultaneously in smart win-dows.These materials have not only demonstrated remarkable potential in the modulation of solar radi-ation but are also leading to the development of indoor environments that are more comfortable and conducive to improving individuals'quality of life.Unfortunately,dual-responsive materials have not received ample research attention due to economic and technological challenges.As a consequence,the broader utilization of smart windows faces hindrances.To address this new generational multi-stimulus responsive chromic materials,our group has adopted a developmental strategy to create a poly(NIPAM)n-HV as a switchable material by anchoring active viologen(HV)onto a phase-changing poly(NIPAM)n-based smart material for better utility and activity.These constructed smart windows facilitate individualistic reversible switching,from a highly transparent state to an opaque state(ther-mochromic)and a red state(electrochromic),as well as facilitate a simultaneous dual-stimuli response reversible switching from a clear transparent state to a fully opaque(thermochromic)and orange(elec-trochromic)states.Absolute privacy can be attained in smart windows designed for exclusive settings by achieving zero transmittance.Each unique chromic mode operates independently and modulates visible and near-infrared(NIR)light in a distinct manner.Hence,these smart windows with thermal and electric dual-stimuli responsiveness demonstrate remarkable heat regulation capabilities,rendering them highly attractive for applications in building facades,energy harvesting,privacy protection,and color display.
查看更多>>摘要：The sluggish kinetics of the electrochemical oxygen reduction reaction(ORR)in intermediate-temperature solid oxide fuel cells(IT-SOFCs)greatly limits the overall cell performance.In this study,an efficient and durable cathode material for IT-SOFCs is designed based on density functional theory(DFT)calculations by co-doping with Nb and Ta the B-site of the SrFeO3-δ perovskite oxide.The DFT cal-culations suggest that Nb/Ta co-doping can regulate the energy band of the parent SrFeO3-δ and help electron transfer.In symmetrical cells,such cathode with a SrFe0.8Nb0.1Ta0.1O3-δ(SFNT)detailed formula achieves a low cathode polarization resistance of 0.147 Ω cm2 at 650 ℃.Electron spin resonance(ESR)and X-ray photoelectron spectroscopy(XPS)analysis confirm that the co-doping of Nb/Ta in SrFeO3-δB-site increases the balanced concentration of oxygen vacancies,enhancing the electrochemical perfor-mance when compared to 20 mol％Nb single-doped perovskite oxide.The cathode button cell with Ni-SDC|SDC|SFNT configuration achieves an outstanding peak power density of 1.3 W cm-2 at 650 ℃.Moreover,the button cell shows durability for 110 h under 0.65 V at 600 ℃ using wet H2 as fuel.
查看更多>>摘要：Carbazole moiety-based 2PACz([2-(9H-carbazol-9-yl)ethyl]phosphonic acid)self-assembled monolayers(SAMs)are excellent hole-selective contact(HSC)materials with abilities to excel the charge-transfer-dynamics of perovskite solar cells(PSCs).Herein,we report a facile but powerful method to functionalize the surface of 2PACz-SAM,by which reproducible,highly stable,high-efficiency wide-bandgap PSCs can be obtained.The 2PACz surface treatment with various donor number solvents improves assembly of 2PACz-SAM and leave residual surface-bound solvent molecules on 2PACz-SAM,which increases per-ovskite grain size,retards halide segregation,and accelerates hole extraction.The surface functionaliza-tion achieves a high power conversion efficiency(PCE)of 17.62％for a single-junction wide-bandgap(～1.77 eV)PSC.We also demonstrate a monolithic all-perovskite tandem solar cell using surface-engineered HSC,showing high PCE of 24.66％with large open-circuit voltage of 2.008 V and high fill-factor of 81.45％.Our results suggest this simple approach can further improve the tandem device,when coupled with a high-performance narrow-bandgap sub-cell.
查看更多>>摘要：Higher nickel content endows Ni-rich cathode materials LiNixCoyMni-x-y02(x＞0.6)with higher specific capacity and high energy density,which is regarded as the most promising cathode materials for Li-ion batteries.However,the deterioration of structural stability hinders its practical application,especially under harsh working conditions such as high-temperature cycling.Given these circumstances,it becomes particularly critical to clarify the impact of the crystal morphology on the structure and high-temperature performance as for the ultrahigh-nickel cathodes.Herein,we conducted a comprehensive comparison in terms of microstructure,high-temperature long-cycle phase evolution,and high-temperature electro-chemical stability,revealing the differences and the working mechanisms among polycrystalline(PC),single-crystalline(SC)and Al doped SC ultrahigh-nickel materials.The results show that the PC sample suffers a severe irreversible phase transition along with the appearance of microcracks,resulting a seri-ous decay of both average voltage and the energy density.While the Al doped SC sample exhibits superior cycling stability with intact layered structure.In-situ XRD and intraparticle structural evolution charac-terization reveal that Al doping can significantly alleviate the irreversible phase transition,thus inhibiting microcracks generation and enabling enhanced structure.Specifically,it exhibits excellent cycling perfor-mance in pouch-type full-cell with a high capacity retention of 91.8％after 500 cycles at 55 ℃.This work promotes the fundamental understanding on the correlation between the crystalline morphology and high-temperature electrochemical stability and provides a guide for optimization the Ni-rich cathode materials.
查看更多>>摘要：Photoelectrochemical(PEC)energy conversion has emerged as a promising and efficient approach to sus-tainable energy harvesting and storage.By utilizing semiconductor photoelectrodes,PEC devices can har-ness solar energy and drive electrochemical reactions such as water splitting or carbon dioxide(CO2)reduction to generate clean fuels and value-added chemicals.However,PEC energy conversion faces sev-eral challenges such as high overpotential,sluggish reaction kinetics,charge carrier recombination,and stability issues,which limit its practical implementation.Recently,significant research has been con-ducted to improve the overall conversion efficiency of PEC devices.One particularly promising approach is the use of cocatalysts,which involves introducing specific cocatalysts onto the photoelectrode surface to promote charge separation,improve reaction kinetics,and reduce the overpotential,thereby enhanc-ing the overall performance of PEC energy conversion.This review provides a comprehensive overview of the recent developments in the earth-abundant cocatalysts for PEC water splitting and CO2 reduction.The main earth-abundant catalysts for the PEC water splitting include transition-metal dichalcogenide(TMD)-based materials,metal phosphides/carbides,and metal oxides/hydroxides.Meanwhile,PEC-CO2RR was divided into C1 and C2+based on the final product since various products could be produced,focusing on diverse earth-abundant materials-based cocatalysts.In addition,we provide and highlight key advancements achieved in the very recent reports on novel PEC system design engineering with cocatalysts.Finally,the current problems associated with PEC systems are discussed along with a sug-gested direction to overcome these obstacles.
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