查看更多>>摘要：Electrocatalytic oxidation reaction of biomass-based derivatives is an excellent candidate to replace water oxidation for obtaining both value-added products and hydrogen(H2),but the exploration of competent electrocatalysts is still highly challenging.Herein,two new types of three-dimensional self-supported hollow microarrays containing CoNi layered double hydroxide(CoNi-LDH)and N-doped carbon nanosheets decorated with CoNi alloyed nanoparticles(CoNi-NC)on carbon cloth(CC)are prepared,which are further used as efficient electrocatalysts for tetrahydroisoquinoline(THIQ)electrooxidation and hydrogen evolution reaction(HER),respectively.We demonstrate that the Co-modulated electronic environment for Ni(Ⅱ)/Ni(Ⅲ)redox-looping in CoNi-LDH is the main factor to boost the selectivity of 3,4-dihydroisoquinoline(DHIQ)for the indirect electrooxidation process of THIQ.Density functional theory(DFT)calculations reveal that the Ni(Ⅲ)/Co(Ⅲ)dual sites of CoNi-LDH exhibit enhanced adsorption for THIQ but poorer adsorption for DHIQ compared to pure Co(Ⅲ)or Ni(Ⅲ).Therefore,the Ni(Ⅲ)/Co(Ⅲ)dual sites can effectively inhibit the peroxidation of DHIQ to isoquinoline(IQ)over CoNi-LDH,thus improving the selectivity of DHIQ to nearly 100％,much higher than that of its pure Ni counterpart.Moreover,CC@CoNi-NC can deliver high HER activity with low overpotential(40 mV@10 mA·cm-2)and high exchange current density(3.08 mA·cm-2).Impressively,the assembled flow-cell device with CC@CoNi-LDH anode and CC@CoNi-NC cathode only requires low cell voltage and electricity consumption of 1.6 V and 3.50 kWh per cubic meter of H2(@25 mA·cm-2).
查看更多>>摘要：The use of supported Co-based catalysts is widespread in various catalytic reactions due to their unique structures.The structural sensitivity of these catalysts is closely linked to their particle size and crystal form.Consequently,comprehending the structure-activity relationship requires the development of well-defined Co-based catalysts.Herein,we employed a colloidal wet chemical process and a heterogeneous nucleation method to prepare well-defined Co-based catalysts supported by inert carbon nanospheres.The nanospheres'surface possesses abundant functional groups that efficiently capture metal complexes and facilitate the nucleation and growth of CoO nanoparticles.By adjusting the Co source concentration,solvent molar ratio,and nucleation growth kinetics,we successfully prepared CoO/carbon sphere(CS)catalysts with different particle sizes and crystal forms.The influence of metallic face-centered cubic(fcc)-Co0 particle size in the range of 6.6-17.6 nm on the performance of Fischer-Tropsch synthesis(FTS)using well-defined CoO/CS catalysts has been investigated.The result demonstrated that the turnover frequency(TOF)remained constant for CoO/CS catalysts with metallic fcc-Co0 particle size larger than 7.7 nm.However,both the selectivity and the activity changed for CoO/CS catalysts with smaller particles(＜7.7 nm).Significantly,when metallic fcc-Co0 particle size was reduced from 17.6 to 7.7 nm,the cobalt time yield increased to 6.7 μmolCO·gCo-1·s-1,indicating improved catalytic activity.At the same time,the CH4 selectivity decreased to 4.9％,suggesting a higher preference for hydrocarbon production.These findings demonstrate the importance of particle size in Co catalyzed Fischer-Tropsch synthesis.The use of well-defined CoO/CS catalysts offers valuable insights into the structure-activity relationship,leading to a better understanding of Co catalyzed Fischer-Tropsch synthesis.
查看更多>>摘要：Transition metal dichalcogenides(TMDs),with the general formula MX2(M=Mo/W/Fe/Co/Ni,etc.;X=S/Se/Te),have attracted extensive research interests for hydrogen evolution reaction(HER).Compared with numerous studies on noble-metal-free TMDs,the chalcogen-dependent HER catalytic properties of noble-metal-based TMDs are lack of sufficient research attention.Herein,a facile electrospinning-assisted synthetic strategy is proposed to synthesize ruthenium dichalcogenides(RuX2,X=S/Se/Te)nanoparticles decorated carbon nanofibers(CNFs).Benefiting from the identical nanofibrous morphology and exposed crystal planes of RuX2(111),the catalytic activities of RuX2@CNFs samples were investigated and compared in a fair and direct manner.Detailed electrochemical measurements coupled with density functional theory calculations were carried out to probe their intrinsic HER catalytic activities,resulting in the catalytic activity order of RuS2@CNFs＞RuSe2@CNFs＞RuTe2@CNFs in acidic media and that of RuS2@CNFs＞RuTe2@CNFs＞RuSe2@CNFs in alkaline media.The superior catalytic performance of RuS2@CNFs mainly stems from the relative lower HER energy barriers and thereby the higher intrinsic catalytic activity of RuS2(111),leading to ultralow overpotentials of 44 and 9 mV at 10 mA·cm-2 in acidic and alkaline media,respectively.RuSe2(111)is endowed with the more optimized Gibbs free energy of hydrogen adsorption(ΔGH*)than RuTe2(111),but RuTe2(111)shows enhanced catalytic property for H2O dissociation and OH-desorption than RuSe2(111),therefore,resulting in the altered catalytic activity sequences for RuSe2 and RuTe2 in acidic and alkaline media.
查看更多>>摘要：The reactant concentration at the catalytic interface holds the key to the activity of electrocatalytic hydrogen evolution reaction(HER),mainly referring to the capacity of adsorbing hydrogen and electron accessibility.With hydrogen adsorption free energy(ΔGH)as a reactivity descriptor,the volcano curve based on Sabatier principle is established to evaluate the hydrogen evolution activity of catalysts.However,the role of electron as reactant received insufficient attention,especially for noble metal-free compound catalysts with poor conductivity,leading to cognitive gap between electronic conductivity and apparent catalytic activity.Herein we successfully construct a series of catalyst models with gradient conductivities by regulating molybdenum disulfide(MoS2)electronic bandgap via a simple solvothermal method.We demonstrate that the conductivity of catalysts greatly affects the overall catalytic activity.We further elucidate the key role of intrinsic conductivity of catalyst towards water electrolysis,mainly concentrating on the electron transport from electrode to catalyst,the electron accumulation process at the catalyst layer,and the charge transfer progress from catalyst to reactant.Theoretical and experimental evidence demonstrates that,with the enhancement in electron accessibility at the catalytic interface,the dominant parameter governing overall HER activity gradually converts from electron accessibility to combination of electron accessibility and hydrogen adsorbing energy.Our results provide the insight from various perspective for developing noble metal-free catalysts in electrocatalysis beyond HER.
查看更多>>摘要：The development of efficient non-precious metal catalysts is important for the large-scale application of alkaline hydrogen evolution reaction(HER).Here,we synthesized a composite catalyst of Cu and Mo2C(Cu/Mo2C)using Anderson-type polyoxometalates(POMs)synthesized by the facile soaking method as precursors.The electronic interaction between Cu and Mo2C drives the positive charge of Cu,alleviating the strong adsorption of hydrogen at the Mo site by modulating the d-band center of Mo2C.By studying the interfacial water structure using in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS),we determined that the positively charged Cu crystals have the function of activating water molecules and optimizing the interfacial water structure.The interfacial water of Cu/Mo2C contains a large amount of free water,which could facilitate the transport of reaction intermediates.Due to activated water molecules and optimized interfacial water structure and hydrogen adsorption energy,the overpotential of Cu/Mo2C is 24 mV at a current density of 10 mA·cm-2 and 178 mV at a current density of 1000 mA·cm-2.This work improves catalyst performance in terms of interfacial water structure optimization and deepens the understanding of water-mediated catalysis.
查看更多>>摘要：Medium-entropy oxides(MEOs)with broad compositional tunability and entropy-driven structural stability,are receiving booming attention as a promising candidate for oxygen evolution reaction(OER)electrocatalysts.Meanwhile,ultrathin two-dimensional(2D)nanostructure offers extremely large specific surface area and is therefore considered to be an ideal catalyst structure.However,it remains a grant challenge to synthesize ultrathin 2D MEOs due to distinct nucleation and growth kinetics of constituent multimetallic elements in 2D anisotropic systems.In this work,an ultrathin 2D MEO(MnFeCoNi)O was successfully synthesized by a facile and low-temperature ionic layer epitaxy method.Benefiting from multi-metal synergistic effects within ultrathin 2D nanostructure,this 2D MEO(MnFeCoNi)O revealed excellent OER electrocatalytic performance with a quite low overpotential of 117 mV at 10 mA·cm-2 and an impressive stability for 120 h continuous operation with only 6.9％decay.Especially,the extremely high mass activity(5584.3 A·g-1)was three orders of magnitude higher than benchmark RuO2(3.4 A·g-1)at the same overpotential of 117 mV.This work opens up a new avenue for developing highly efficient and stable electrocatalysts by creating 2D nanostructured MEOs.
查看更多>>摘要：Lithium is known as the"white petroleum"of the electrification era,and the global demand for lithium grows rapidly with the quick development of new energy industry.The aqueous solutions,such as salt lake brine,underground brine,and seawater,have large lithium reserves,thus this kind of lithium resource has become a research hotspot recently.Compared with other lithium extraction technologies,electro-sorption method shows good prospects for practical applications with advantages in the aspects of efficiency,recovery ratio,cost,and environment.Herein,this review covers recent progress on electro-sorption technology for lithium recovery from aqueous solutions,including the concept illustration,research progress of the applied working electrodes and counter electrodes,and the evaluation indicators of electro-sorption system.Meanwhile,some prospects for the development of this technology are also proposed.We hope this review is beneficial for the construction of high-efficient electrochemical lithium recovery system to achieve an adequate lithium supply in the future.
查看更多>>摘要：Lithium-sulfur(Li-S)batteries,known for their high energy density,are attracting extensive research interest as a promising next-generation energy storage technology.However,their widespread use has been hampered by certain issues,including the dissolution and migration of polysulfides,along with sluggish redox kinetics.Metal sulfides present a promising solution to these obstacles regarding their high electrical conductivity,strong chemical adsorption with polysulfides,and remarkable electrocatalytic capabilities for polysulfide conversion.In this review,the recent progress on the utilization of metal sulfide for suppressing polysulfide shuttling in Li-S batteries is systematically summarized,with a special focus on sulfur hosts and functional separators.The critical roles of metal sulfides in realizing high-performing Li-S batteries have been comprehensively discussed by correlating the materials'structure and electrochemical performances.Moreover,the remaining issues/challenges and future perspectives are highlighted.By offering a detailed understanding of the crucial roles of metal sulfides,this review dedicates to contributing valuable knowledge for the pursuit of high-efficiency Li-S batteries based on metal sulfides.
查看更多>>摘要：Li-S batteries(LSBs)have been considering as new and promising energy storage systems because of the high theoretical energy density and low price.Nevertheless,their practical application is inhibited by several factors,including poor electrical conductivity of electrode materials,greatly volumetric variation,as well as the polysulfide formation upon the cycling.To address these problems,it is imperative to develop and design effective and suitable sulfur host anode materials.Metal organic frameworks(MOFs)-based cathode materials,possessing their good conductivity and easy morphology design,have been extensively studied and exhibited enormously potential in LSBs.In this review,a comprehensive overview of MOFs-based sulfur host materials is provided,including their electrochemical reaction mechanisms,related evaluation parameters,and their performances used in LSBs in the past few years.In particular,the recent advances using in-situ characterization technologies for investigating the electrochemical reaction mechanism in LSBs are presented and highlighted.Additionally,the challenges and prospects associated with future research on MOF-related sulfur host materials are discussed.It is anticipated to offer the guidance for the identification of suitable MOFs-based sulfur cathode materials for high-performance LSBs,thereby contributing for the achievement of a sustainable and renewable society.
查看更多>>摘要：Carbonaceous materials have been recognized as one of the most promising anode materials for potassium-ion batteries(PIBs)due to their abundant raw materials,controllable structure,superior conductivity,and good chemical inertness.However,the large radius of K ions and the low potassium content of intercalation compounds result in the sluggish storage kinetics and low reversible capacity of carbon anodes.In this work,we present a unique heteroatom-doped carbon composite(denoted as NS-MC/SC)through a facile interfacial assembly route and simple heat-treatment process,where NS-MC is well grafted onto the biomass-derived spore carbon(SC).This unique structural design endows it with abundant mesoporous channels,expanded layer spacing,and highly doped N and S.With these merits,the NS-MC/SC anode in PIBs exhibits a high reversible capacity of 350.4 mAh·g-1 at 100 mA·g-1 after 300 cycles,and an outstanding cycling stability.Besides,in-situ Raman spectra further verify the high reversibility of K ions insertion/extraction.Importantly,theoretical simulations also reveal that the N,S dual-doping is an efficient approach for improving the potassium-ion storage performance of NS-MC/SC.
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