Lithium-sulfur(Li-S)batteries are regarded as the most formidable competitor to lithium-ion batteries due to their superior theoretical capacity.However,the negative impact of soluble lithium polysulfide(LiPSs)and slo...Lithium-sulfur(Li-S)batteries are regarded as the most formidable competitor to lithium-ion batteries due to their superior theoretical capacity.However,the negative impact of soluble lithium polysulfide(LiPSs)and slow redox reaction kinetics seriously hamper the commercialization of Li-S batteries.In this study,a defect-rich single-atom catalyst with an oversaturated asymmetric Fe-N_(5)coordination structure anchored in defective g-C_(3)N_(4)(C_(3)N_(4)-Fe@rGO)is designed via an absorption-pyrolysis strategy.The two-dimensional(2D)conducting C_(3)N_(4)@graphene structure with abundant defect sites accelerates the trans-fer and transportation of lithium ions and electrons.The oversaturated asymmetric Fe-N_(5)coordination structure effectively improves the adsorbility of LiPSs and accelerates the redox kinetics of sulfur species.Hence,the Li-S cell with a C_(3)N_(4)-Fe@rGO modified separator reveals a high initial capacity(1197.1 mAh g^(-1) at 0.2 C)and a low capacity decay rate(0.037%per cycle after 900 cycles at 1 C).Even at high sulfur loading and extreme temperatures of 0℃,it also shows good cycling performance.This work creates ideas for synthesizing oversaturated single-atom coordination environments and an efficient route to the practical realization of the Li-S batteries.展开更多
Oxygen reduction reaction(ORR)in neutral electrolyte is urgently needed in various areas,such as metalair batteries.However,the N-coordinated transition-metal single-atom electrocatalysts confront sluggish catalytic k...Oxygen reduction reaction(ORR)in neutral electrolyte is urgently needed in various areas,such as metalair batteries.However,the N-coordinated transition-metal single-atom electrocatalysts confront sluggish catalytic kinetics due to the inappropriate electronic structure and the as-resulted unreasonable adsorption strength towards oxygen-containing intermediates.In this work,we develop a strategy to tune the Fe d-orbital spin state by introducing inert Si atom into the first coordination sphere of Fe-N_(4)moieties.The experimental and theoretical results suggest that Si atom generates the coordination field distortion of Fe and induces the Fe d-orbital spin state transforming from low to medium spin state.The optimized spin-electron filled state(t2g^(4)eg^(1))of Fe sites weakens the adsorption strength to intermediates and reduces the energy barrier of^(∗)OH desorption.Consequently,Fe-Si/NC catalyst exhibits superior ORR performance compared with that of Fe-NC and commercial Pt/C,showing a more positive half-wave potential of 0.753 V(vs.RHE)in 0.1 mol/L phosphate buffered saline.In addition,Fe-Si/NC-based neutral zinc-air batteries show a maximum power density of 108.9 mW cm^(−2)and long-term stability for 200 h.This work represents the possibility of constructing distorted coordination configurations of single-atom catalysts to modulate electronic structure and enhance ORR activity in neutral electrolyte.展开更多
With the rapid development of economy,the consumption of fossil fuels and excessive emissions of carbon dioxide(CO_(2))have led to many environmental issues.The thermocatalytic conversion of CO_(2) to high value‐adde...With the rapid development of economy,the consumption of fossil fuels and excessive emissions of carbon dioxide(CO_(2))have led to many environmental issues.The thermocatalytic conversion of CO_(2) to high value‐added chemicals is an effective strategy to meet the need of carbon neutralization.Among them,CO_(2) hydrogenation to light olefins has been well researched so that the selectivity of desired products can exceed the Anderson–Schulz–Flory(ASF)distribution to acquire an extremely high yield.However,although huge progress has been made in CO_(2) hydrogenation to produce long‐chain α‐olefins based on Fe catalysts as well,designing efficient catalysts with promoted C‐O dissociation and C‐C coupling remains challenging.In addition,ASF distribution restrains the selectivity of desired long‐chain products,whereas the approaches to breaking it still face issues.In this review,we focus on the design of Fe‐based catalysts for the synthesis of long‐chainα‐olefins through CO_(2) hydrogenation.We have summarized and analyzed the reaction mechanism,design of catalysts,structure–activity relationship,interaction between Fe and promoters,and strategies to break the ASF distribution.At the same time,the issues faced by CO_(2) hydrogenation to long‐chain α‐olefins are proposed and the possible future solutions are prospected.This review aims to provide a recent development on the design of Fe‐based catalysts for CO_(2) hydrogenation to long‐chain α‐olefins while considering the ASF distribution.展开更多
Proton exchange membrane fuel cells(PEMFCs)constitute a promising avenue for environmentally friendly power generation.However,the reliance on unsustainable platinum-based electrocatalysts used at the electrodes poses...Proton exchange membrane fuel cells(PEMFCs)constitute a promising avenue for environmentally friendly power generation.However,the reliance on unsustainable platinum-based electrocatalysts used at the electrodes poses challenges to the commercial viability of PEMFCs.Non-platinum group metal(non-PGM)alternatives,like nitrogen-coordinated transition metals in atomic dispersion(M–N–C catalysts),show significant potential.This work presents a comparative study of two distinct sets of Fe–N–C materials,prepared by pyrolyzing hybrid composites of polyaniline(PANI)and iron(Ⅱ)chloride on a hard template.One set uses bipyridine(BPy)as an additional nitrogen source and iron ligand,offering an innovative approach.The findings reveal that the choice of pyrolysis temperature and atmosphere influences the catalyst properties.The use of ammonia in pyrolysis emerges as a crucial parameter for promoting atomic dispersion of iron,as well as increasing surface area and porosity.The optimal catalyst,prepared using BPy and ammonia,exhibits a half-wave potential of 0.834 V in 0.5 M H_(2)SO_(4)(catalyst loading of 0.6 mg cm^(-2)),a mass activity exceeding 3 A g^(-1)and high stability in acidic electrolyte,positioning it as a promising non-PGM structure in the field.展开更多
A variety of spherical and structured activated charcoal supported Pt/Fe3O4 composites with an average particle size of ~100 nm have been synthesized by a self-assembly method using the difference of reduction potenti...A variety of spherical and structured activated charcoal supported Pt/Fe3O4 composites with an average particle size of ~100 nm have been synthesized by a self-assembly method using the difference of reduction potential between Pt （Ⅳ） and Fe （Ⅱ） precursors as driving force. The formed Fe3O4 nanoparticles （NPs） effectively prevent the aggregation of Pt nanocrystallites and promote the dispersion of Pt NPs on the surface of catalyst, which will be favorable for the exposure of Pt active sites for high-efficient adsorption and contact of substrate and hydrogen donor. The electron-enrichment state of Pt NPs donated by Fe304 nanocrystallites is corroborated by XPS measurement, which is responsible for promoting and activating the terminal C=O bond of adsorbed substrate via a vertical configuration. The experimental results show that the activated charcoal supported Pt/Fe3O4 catalyst exhibits 94.8% selectivity towards cinnamyl alcohol by the transfer hydrogenation of einnamaldehyde with Pt loading of 2.46% under the optimum conditions of 120 ℃ for 6 h, and 2-propanol as a hydrogen donor. Additionally, the present study demonstrates that a high-efficient and recyclable catalyst can be rapidly separated from the mixture due to its natural magnetism upon the application of magnetic field.展开更多
Fe/N/C is a promising non-platinum catalyst for the oxygen reduction reaction （ORR）. Even so, mass transfer remains a challenge in the application of Fe/N/C to proton exchange membrane fuel cells, due to the high ca...Fe/N/C is a promising non-platinum catalyst for the oxygen reduction reaction （ORR）. Even so, mass transfer remains a challenge in the application of Fe/N/C to proton exchange membrane fuel cells, due to the high catalyst loadings required. In the present work, mesoporous Fe/N/C was syn- thesized through heat treatment of K]600 carbon black coated with poly-2-aminobenzimidazole and FeC13. The as-prepared Fe/N/C possesses a unique hollow-shell structure that contains a buffer zone allowing both water formation and vaporization, and also facilitates the mass transfer of gas- eous oxygen. This catalyst generated an oxygen reduction reaction activiW of 9.21 A/g in conjunc- tion with a peak power density of 0.71 W/cm2.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U21A2060 and 22178116)the Natural Science Foundation of Shanghai(No.22ZR1417400)the Fundamental Research Funds for the Central Universities(Nos.222201817001,50321041918013,JKA01221601,JKD01241701).
文摘Lithium-sulfur(Li-S)batteries are regarded as the most formidable competitor to lithium-ion batteries due to their superior theoretical capacity.However,the negative impact of soluble lithium polysulfide(LiPSs)and slow redox reaction kinetics seriously hamper the commercialization of Li-S batteries.In this study,a defect-rich single-atom catalyst with an oversaturated asymmetric Fe-N_(5)coordination structure anchored in defective g-C_(3)N_(4)(C_(3)N_(4)-Fe@rGO)is designed via an absorption-pyrolysis strategy.The two-dimensional(2D)conducting C_(3)N_(4)@graphene structure with abundant defect sites accelerates the trans-fer and transportation of lithium ions and electrons.The oversaturated asymmetric Fe-N_(5)coordination structure effectively improves the adsorbility of LiPSs and accelerates the redox kinetics of sulfur species.Hence,the Li-S cell with a C_(3)N_(4)-Fe@rGO modified separator reveals a high initial capacity(1197.1 mAh g^(-1) at 0.2 C)and a low capacity decay rate(0.037%per cycle after 900 cycles at 1 C).Even at high sulfur loading and extreme temperatures of 0℃,it also shows good cycling performance.This work creates ideas for synthesizing oversaturated single-atom coordination environments and an efficient route to the practical realization of the Li-S batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.52422314,U23A20687,and 52231008)the International Science&Technology Cooperation Program of Hainan Province(No.GHYF2023007).
文摘Oxygen reduction reaction(ORR)in neutral electrolyte is urgently needed in various areas,such as metalair batteries.However,the N-coordinated transition-metal single-atom electrocatalysts confront sluggish catalytic kinetics due to the inappropriate electronic structure and the as-resulted unreasonable adsorption strength towards oxygen-containing intermediates.In this work,we develop a strategy to tune the Fe d-orbital spin state by introducing inert Si atom into the first coordination sphere of Fe-N_(4)moieties.The experimental and theoretical results suggest that Si atom generates the coordination field distortion of Fe and induces the Fe d-orbital spin state transforming from low to medium spin state.The optimized spin-electron filled state(t2g^(4)eg^(1))of Fe sites weakens the adsorption strength to intermediates and reduces the energy barrier of^(∗)OH desorption.Consequently,Fe-Si/NC catalyst exhibits superior ORR performance compared with that of Fe-NC and commercial Pt/C,showing a more positive half-wave potential of 0.753 V(vs.RHE)in 0.1 mol/L phosphate buffered saline.In addition,Fe-Si/NC-based neutral zinc-air batteries show a maximum power density of 108.9 mW cm^(−2)and long-term stability for 200 h.This work represents the possibility of constructing distorted coordination configurations of single-atom catalysts to modulate electronic structure and enhance ORR activity in neutral electrolyte.
基金supported by the CNPC Innovation Found(2021DQ02‐0702).
文摘With the rapid development of economy,the consumption of fossil fuels and excessive emissions of carbon dioxide(CO_(2))have led to many environmental issues.The thermocatalytic conversion of CO_(2) to high value‐added chemicals is an effective strategy to meet the need of carbon neutralization.Among them,CO_(2) hydrogenation to light olefins has been well researched so that the selectivity of desired products can exceed the Anderson–Schulz–Flory(ASF)distribution to acquire an extremely high yield.However,although huge progress has been made in CO_(2) hydrogenation to produce long‐chain α‐olefins based on Fe catalysts as well,designing efficient catalysts with promoted C‐O dissociation and C‐C coupling remains challenging.In addition,ASF distribution restrains the selectivity of desired long‐chain products,whereas the approaches to breaking it still face issues.In this review,we focus on the design of Fe‐based catalysts for the synthesis of long‐chainα‐olefins through CO_(2) hydrogenation.We have summarized and analyzed the reaction mechanism,design of catalysts,structure–activity relationship,interaction between Fe and promoters,and strategies to break the ASF distribution.At the same time,the issues faced by CO_(2) hydrogenation to long‐chain α‐olefins are proposed and the possible future solutions are prospected.This review aims to provide a recent development on the design of Fe‐based catalysts for CO_(2) hydrogenation to long‐chain α‐olefins while considering the ASF distribution.
基金funding from the Hellenic Foundation for Research and Innovation(HFRI)under grant agreement No 3655.
文摘Proton exchange membrane fuel cells(PEMFCs)constitute a promising avenue for environmentally friendly power generation.However,the reliance on unsustainable platinum-based electrocatalysts used at the electrodes poses challenges to the commercial viability of PEMFCs.Non-platinum group metal(non-PGM)alternatives,like nitrogen-coordinated transition metals in atomic dispersion(M–N–C catalysts),show significant potential.This work presents a comparative study of two distinct sets of Fe–N–C materials,prepared by pyrolyzing hybrid composites of polyaniline(PANI)and iron(Ⅱ)chloride on a hard template.One set uses bipyridine(BPy)as an additional nitrogen source and iron ligand,offering an innovative approach.The findings reveal that the choice of pyrolysis temperature and atmosphere influences the catalyst properties.The use of ammonia in pyrolysis emerges as a crucial parameter for promoting atomic dispersion of iron,as well as increasing surface area and porosity.The optimal catalyst,prepared using BPy and ammonia,exhibits a half-wave potential of 0.834 V in 0.5 M H_(2)SO_(4)(catalyst loading of 0.6 mg cm^(-2)),a mass activity exceeding 3 A g^(-1)and high stability in acidic electrolyte,positioning it as a promising non-PGM structure in the field.
基金This work is supported by the National Natural Science Foundation of China （No.51372248, No.51432009 and No.51502297）, Instrument Developing Project of the Chinese Academy of Sciences （No.yz201421）, the CAS/SAFEA International Partnership Program for Creative Research Teams of Chinese Academy of Sciences, China.
文摘A variety of spherical and structured activated charcoal supported Pt/Fe3O4 composites with an average particle size of ~100 nm have been synthesized by a self-assembly method using the difference of reduction potential between Pt （Ⅳ） and Fe （Ⅱ） precursors as driving force. The formed Fe3O4 nanoparticles （NPs） effectively prevent the aggregation of Pt nanocrystallites and promote the dispersion of Pt NPs on the surface of catalyst, which will be favorable for the exposure of Pt active sites for high-efficient adsorption and contact of substrate and hydrogen donor. The electron-enrichment state of Pt NPs donated by Fe304 nanocrystallites is corroborated by XPS measurement, which is responsible for promoting and activating the terminal C=O bond of adsorbed substrate via a vertical configuration. The experimental results show that the activated charcoal supported Pt/Fe3O4 catalyst exhibits 94.8% selectivity towards cinnamyl alcohol by the transfer hydrogenation of einnamaldehyde with Pt loading of 2.46% under the optimum conditions of 120 ℃ for 6 h, and 2-propanol as a hydrogen donor. Additionally, the present study demonstrates that a high-efficient and recyclable catalyst can be rapidly separated from the mixture due to its natural magnetism upon the application of magnetic field.
基金supported by the National Basic Research Program of Chain(973 Program,2015CB932300)the National Natural Science Foundation of China(21373175,21321062,21361140374)Fundamental Research Funds for the Central Universities(20720150109)
文摘Fe/N/C is a promising non-platinum catalyst for the oxygen reduction reaction （ORR）. Even so, mass transfer remains a challenge in the application of Fe/N/C to proton exchange membrane fuel cells, due to the high catalyst loadings required. In the present work, mesoporous Fe/N/C was syn- thesized through heat treatment of K]600 carbon black coated with poly-2-aminobenzimidazole and FeC13. The as-prepared Fe/N/C possesses a unique hollow-shell structure that contains a buffer zone allowing both water formation and vaporization, and also facilitates the mass transfer of gas- eous oxygen. This catalyst generated an oxygen reduction reaction activiW of 9.21 A/g in conjunc- tion with a peak power density of 0.71 W/cm2.
