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Identification of the optimal doping position of hetero-atoms in chalcogen-doped Fe-N-C catalysts for oxygen reduction reaction

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Particuology 2024年第6期89卷 99-108页

作者： Weihao Liu Huanhuan He Qingtao Liu Xin Wan jianglan shui School of Materials Science and Engineering Beihang UniversityBeijing100191China School of Space and Environment Beihang UniversityBeijing102206China Tianmushan Laboratory Hangzhou310023China

The excellent oxygen reduction reaction(ORR)activity of Fe–N–C catalysts in acidic media makes them potential for low-cost proton exchange membrane fuel *** recent years,it has been shown that heteroatoms(B,O,S,P,Cl,F,etc.)can be used as electron-withdrawing groups to modulate the planar structure and electron distribution of the Fe–Nx active sites to achieve simultaneous improvement of catalytic activity and ***,the optimal location of the heteroatoms remains ***,taking chalcogen heteroatoms(S and Se)as an example,we control the doping positions and investigate their effect on the ORR performance of the Fe–N–C *** first coordination shell of the iron single atom is identified as the optimal doping *** optimized catalysts Fe–N_(3)Se_(1)/NC and Fe–N_(3)Se_(1)/NC demonstrate improved activity and stability in both half cells and fuel *** work provides insights into the enhancement mechanism of heteroatom doping in single-atom catalysts.

关键词： Oxygen reduction reaction Fe-N-C catalysts Hetero-atom doping Doping position Enhancement mechanism

Critical role of carbon support in metal nanoaggregate facilitating Fe-N-C catalyst for PEM fuel cell application

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Journal of Energy Chemistry 2024年第10期97卷 669-676页

作者： Liming Guo Xin Wan Qingtao Liu Xiaofang Liu Jiaxiang Shang Ronghai Yu jianglan shui School of Materials Science and Engineering Beihang University Tianmushan Laboratory

Metal nanoaggregates can simultaneously enhance the activity and stability of Fe-N-C catalysts in proton-exchange-membrane fuel cells（PEMFC）.Previous studies on the relevant mechanism have focused on the direct interaction between FeN4active sites and metal ***,the role of carbon support that hosts metal nanoaggregates and active sites has been ***,a Fe-N-C catalyst encapsulating inactive gold nanoparticles is prepared as a model catalyst to investigate the electronic tuning of Au nanoparticles（NPs） towards the carbon *** NPs donate electrons to carbon support,making it rich in π electrons,which reduces the work function and regulates the electronic configuration of the FeN4sites for an enhanced ORR ***,the electron-rich carbon support can mitigate the electron depletion of FeN4sites caused by carbon support oxidation,thereby preserving its high *** yield and accumulation of H2O2are thus alleviated,which delays the oxidation of the catalyst and benefits the *** to the electron-rich carbon support,the composite catalyst achieves a top-level peak power density of 0.74 W/cm2in a 1.5 bar H2-air PEMFC,as well as the improved *** work elucidates the key role of carbon support in the performance enhancement of the FeN-C/metal nanoaggregate composite catalysts for fuel cell application.

关键词： Carbon support Fe-N-C Fuel cells Hetero-structure catalyst Oxygen reduction reaction

A post-modification strategy to precisely construct dual-atom sites for oxygen reduction electrocatalysis

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Journal of Energy Chemistry 2024年第3期90卷 511-517,I0012页

作者： Juan Wang Xinyan Liu Chang-Xin Zhao Yun-Wei Song Jia-Ning Liu Xi-Yao Li Chen-Xi Bi Xin Wan jianglan shui Hong-Jie Peng Bo-Quan Li Jia-Qi Huang School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical EngineeringTsinghua UniversityBeijing 100084China Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 611731SichuanChina School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Dual-atom catalysts(DACs) afford promising potential for oxygen reduction electrocatalysis due to their high atomic efficiency and high intrinsic ***,precise construction of dual-atom sites remains a *** this work,a post-modification strategy is proposed to precisely fabricate DACs for oxygen reduction ***,a secondary metal precursor is introduced to the primary single-atom sites to introduce direct metal-metal interaction,which ensures the formation of desired atom pair structure during the subsequent pyrolysis process and allows for successful construction of *** as-prepared FeCo-NC DAC exhibits superior oxygen reduction electrocatalytic activity with a half-wave potential of 0,91 V *** hydrogen ***-air batteries equipped with the FeCo-NC DAC demonstrate higher peak power density than those with the Pt/C *** importantly,this post-modification strategy is demonstrated universal to achieve a variety of dual-atom *** work presents an effective synthesis methodology for precise construction of catalytic materials and propels their applications in energy-related devices.

关键词： Dual-atom catalysts Electrocatalysis Oxygen reduction reaction Post-modification Zinc–air batteries

Boosting the Oxygen Reduction Performance of Fe–N–C Catalyst Using Zeolite as an Oxygen Reservoir

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Transactions of Tianjin University 2024年第05期 428-435页

作者： Weihao Liu Qingtao Liu Xin Wan jianglan shui School of Materials Science and Engineering Beihang University School of Space and Environment Beihang University Tianmushan Laboratory

Non-precious metal electrocatalysts（such as Fe–N–C materials） for the oxygen（O2） reduction reaction demand a high catalyst loading in fuel cell devices to achieve workable performance. However, the extremely low solubility of O2in water creates severe mass transport resistance in the thick catalyst layer of Fe–N–C catalysts. Here, we introduce silicalite-1 nanocrystals with hydrophobic cavities as sustainable O2reservoirs to overcome the mass transport issue of Fe–N–C catalysts. The extra O2supply to the adjacent catalysts significantly alleviated the negative effects of the severe mass transport resistance. The hybrid catalyst（Fe–N–C@silicalite-1） achieved a higher limiting current density than Fe–N–C in the half-cell test. In the H2–O2and H2–air proton exchange membrane fuel cells, Fe–N–C@silicalite-1 exhibited a 16.3% and 20.2% increase in peak power density compared with Fe–N–C, respectively. The O2-concentrating additive provides an effective approach for improving the mass transport imposed by the low solubility of O2in water.

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Stability of PGM-free fuel cell catalysts: Degradation mechanisms and mitigation strategies

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Progress in Natural Science:Materials International 2020年第6期30卷 721-731页

作者： Xin Wan Xiaofang Liu jianglan shui School of Materials Science and Engineering Beihang University

While Platinum group metals(PGM) free catalysts are promising alternatives to expensive Pt as the cathode catalyst in proton exchange membrane fuel cells, their rapid degradation must be addressed for the commercial feasibility. This review provides a historical survey of the possible degradation mechanisms of PGM-free catalysts. Decades of extensive studies confirm that carbon oxidation and demetalation are primarily responsible for the instability, whereas the mechanisms of protonation and micropore flooding are strongly criticized. Based on the mechanism understanding, the mitigation strategies for improving stability are discussed in detail. Finally,some directions to achieve high-performance and durable PGM-free catalysts are proposed.

关键词： Fuel cell Oxygen reduction PGM-Free catalysts Stability Mitigation strategy

Performance improvement of lithium-ion battery by pulse current

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Journal of Energy Chemistry 2020年第7期29卷 208-214,I0007页

作者： Shaoqing Zhu Chen Hu Ye Xu Yi Jin jianglan shui School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China State Key Laboratory of Operation and Control of Renewable Energy&Storage Systems China Electric Power Research InstituteBeijing 100192China School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Periodically changed current is called pulse *** has been found that using the pulse current to charge/discharge lithium-ion batteries can improve the safety and cycle stability of the *** this short review,the mechanisms of pulse current improving the performance of lithium-ion batteries are summarized from four aspects:activation,warming up,fast charging and inhibition of lithium *** content may help us use the pulse current to improve the performance of lithium-ion batteries and further optimize pulse current technology.

关键词： Lithium ion battery Pulse current Activation Warming up Fast charging Lithium dendrites

High-throughput screening of carbon-supported single metal atom catalysts for oxygen reduction reaction

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Nano Research 2022年第2期15卷 1054-1060页

作者： Yiran Wang Riming Hu Yongcheng Li Fuhe Wang Jiaxiang Shang jianglan shui School of Materials Science and Engineering Beihang UniversityBeijing 100191China Qinghai Provincial Key Laboratory of New Light Alloys Qinghai Provincial Engineering Research Center of High-Performance Light Metal Alloys and FormingQinghai UniversityXining 810016China Center for Condensed Matter Physics Department of Physics Capital Normal UniversityBeijing 100048China

Carbon-supported transition metal single atoms are promising oxygen reduction reaction(ORR)*** there are many types of carbon supports and transition metals,the accurate prediction of the components with high activity through theoretical calculations can greatly save experimental time and *** this work,the ORR catalytic properties of 180 types single-atom catalysts(SACs)composed of the eight representative carbon-based substrates(graphdiyne,C_(2)N,C_(3)N_(4),phthalocyanine,C-coordination graphene,N-coordination graphene,covalent organic frameworks and metal-organic frameworks)and 3d,4d,and 5d transition metal elements are investigated by density functional theory(DFT).The adsorption free energy of OH^(*) is proved a universal descriptor capable of accurately prediction of the ORR catalytic *** is found that the oxygen reduction reaction overpotentials of all the researched SACs follow one volcano shape very well with the adsorption free energy of OH^(*).Phthalocyanine,N-coordination graphene and metal-organic frameworks stand out as the promising supports for single metal atom due to the relatively lower ***,the Co-doped metal-organic frameworks,Ir-doped phthalocyanine,Co-doped N-coordination graphene,Co-doped graphdiyne and Rh-doped phthalocyanine show extremely low overpotentials comparable to that of Pt(111).The study provides a guideline for design and selection of carbon-supported SACs toward oxygen reduction reaction.

关键词： oxygen reduction reaction carbon-supported catalysts high throughput screening density functional theory single-atom catalysts

Effect of Zn atom in Fe-N-C catalysts for electro-catalytic reactions: theoretical considerations

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Nano Research 2021年第3期14卷 611-619页

作者： Yongcheng Li Riming Hu Zhibin Chen Xin Wan Jia-Xiang Shang Fu-He Wang jianglan shui School of Materials Science and Engineering Beihang UniversityBeijing100191China Department of Physics Capital Normal UniversityBeijing100048China

Due to the high specific surface area,abundant nitrogen and micropores,ZIF-8 is a commonly used precursor for preparing high performance Fe-N-C ***,the Zn element is inevitably remained in the prepared Fe-N-C *** the residual Zn element affects the catalytic activity and active site center of the Fe-N-C catalyst caused widespread curiosity,but has not been studied ***,we built several Fe,Zn,and N co-doped graphene models to investigate the effect of Zn atoms on the electrocatalytic performance of Fe-N-C catalysts by using density functional theory *** calculation results show that all the calculated Fe-Zn-N_(x) structures are thermodynamically stable due to the negative formation energies and relative *** active sites around Fe and Zn atoms in the structure of Fe-Zn-N_(6)(III)show the lowest oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)overpotentials of 0.38 and 0.43 V,*** bridge site of Fe-Zn in Fe-Zn-N_(5) shows the lowest η^(HER) of−0.26 V.A few structures with a better activity than that of FeN_(4) or ZnN_(4) are attributed to the synergistic effects between Fe and Zn *** calculated ORR reaction pathways on Fe-Zn-N6(III)show that H_(2)O is the final product and the ORR mechanism on the catalyst would be a four-electron process,and the existence of Zn element in the Fe-N-C catalysts plays a key role in reducing the ORR activation energy *** results are helpful for the deep understand of high-performance Fe-N-C catalysts.

关键词： Fe-N-C Zn-N-C oxygen reduction reaction oxygen evolution reaction hydrogen evolution reaction density functional theory

Environmentally Tough and Stretchable MXene Organohydrogel with Exceptionally Enhanced Electromagnetic Interference Shielding Performances

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Nano-Micro Letters 2022年第5期14卷 77-91页

作者： Yuanhang Yu Peng Yi Wenbin Xu Xin Sun Gao Deng Xiaofang Liu jianglan shui Ronghai Yu School of Materials Science and Engineering Beihang UniversityBeijing 100191People’s Republic of China Science and Technology on Optical Radiation Laboratory Beijing Institute of Environmental FeaturesBeijing 100854People’s Republic of China Science and Technology on Electromagnetic Scattering Laboratory Beijing Institute of Environmental FeaturesBeijing 100854People’s Republic of China

Conductive hydrogels have potential applications in shielding electromagnetic(EM)radiation interference in deformable and wearable electronic devices,but usually suffer from poor environmental stability and stretching-induced shielding performance *** organohydrogels can improve the environmental stability of materials,their development is at the expense of reducing electrical conductivity and thus weakening EM interference shielding ***,a MXene organohydrogel is prepared which is composed of MXene network for electron conduction,binary solvent channels for ion conduction,and abundant solvent-polymer-MXene interfaces for EM wave *** organohydrogel possesses excellent anti-drying ability,low-temperature tolerance,stretchability,shape adaptability,adhesion and rapid self-healing *** effective strategies have been proposed to solve the problems of current organohydrogel shielding *** reasonably controlling the MXene content and the glycerol-water ratio in the gel,MXene organohydrogel can exhibit exceptionally enhanced EM interference shielding performances compared to MXene hydrogel due to the increased physical cross-linking density of the ***,MXene organohydrogel shows attractive stretching-enhanced interference effectiveness,caused by the connection and parallel arrangement of MXene *** well-designed MXene organohydrogel has potential applications in shielding EM interference in deformable and wearable electronic devices.

关键词： Electromagnetic interference shielding MXene organohydrogel Stretchable conductive film Anti-drying ability Lowtemperature tolerance