JOURNAL OF ALLOYS AND COMPOUNDS
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2020
·
IF 4.65
Jiahao Yu,Jieyi Yu,Tongpan Ying,Xianguo Liu,Xuefeng Zhang,Dandan Han
Three main strategies for designing efficient microwave absorber includes the intrinsic dielectric/magnetic properties, the novel structure and the single atom doping. The Fe-N/C nanocomposites integrate the advantages of above three strategies into one system. In this work, the method for preparing Fe-N/C nanocomposite by calcining the FePc@ZIF-8 precursor under a flowing N 2 gas is described. Fe-N/C nanocomposites, displaying respectable dodecahedron-like morphology, have the merits of strong absorption ability, wide effective absorption bandwidth, thin thickness, and excellent microwave absorption efficiency, which are attributed to the synergistic effect of good electromagnetic loss capacity and proper impedance matching originating from intrinsic dielectric/magnetic properties, the novel structure and the single atoms (Fe and N) doping. Fe-N/C-24 composite delivers an optimal reflection loss of −30.98 dB, an effective absorption bandwidth of 5.04 GHz, the microwave absorption capacity of 87.61 dB GHz the absorption efficiency of 51.53 dB GHz/mm at 1.7 mm.
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高影响因子
CHEMISTRY-A EUROPEAN JOURNAL
·
2024
·
IF 3.9
Tingting Xiang,Qingchao Zhu,Tanyu Zhou,Chenglong Chen,Ruibo Wang,Tieyu Hu,Bing Li,Ziwei Xu,Juan Yang
Graphical Fe−N−C catalysts, doped with phosphorus, show improved ORR activity. Fe-NPC catalyst exhibits high metal loading, excellent ORR performance (onset potential of 1.00 V, half-wave potential of 0.864 V), and promising application in Zn-air batteries (758.8 mAh g −1 Zn ). DFT calculations reveal that phosphorus enhances O 2 activation and reduces the energy barrier for the rate-determining step. Atomically dispersed iron and nitrogen co-doped carbon materials (Fe−N−C) represent promising non-precious metal catalysts for the oxygen reduction reaction (ORR), offering potential alternatives to noble metal-based benchmarks. In our study, we investigated the influence of phosphorus doping on the catalytic activity of Fe−N−C. The experimental research demonstrate that the doping of phosphorus significantly enhances the ORR activity. Specifically, the resulting Fe-NPC exhibits high metal loading and excellent ORR activity in 0.1 M KOH with an onset potential of 1.00 V and a half-wave potential of 0.864 V. Density functional theory (DFT) simulations reveal that phosphorus improves the electrocatalytic activity by activating O2 molecules and reducing the energy barrier (the hydrogenation reaction *OH→H2O) of the rate-determining step. Furthermore, Fe-NPC exhibits promising application prospects as an air cathode in Zn-air batteries, delivering a high maximum discharge power density of 180.3 mW cm −2 and outstanding discharge specific capacity (758.8 mAh g −1 Zn ) at a discharge current density of 10 mA cm −2 .
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JOURNAL OF SOLID STATE CHEMISTRY
·
2024
·
IF 3.2
Lang Wang,Yonghang Zhang,Linxiang Zhou,Guangtao Luo,Zhiwei Meng,Haodong Jin,Enze Zhu,Mingli Xu
The cathode's oxygen reduction reaction (ORR) plays a crucial role in a variety of fuel cells. Developing affordable and efficient non-precious electrocatalysts for the ORR poses a major hurdle in the realm of electrochemical energy technologies. This work presents a transition metal-based catalyst, Fe-ONC, in which Fe is loaded in an oxygen-enriched nitrogen-doped carbon (NC) material. Oxygen enrichment of the catalyst was achieved by a pre-oxidation strategy. The XPS analysis reveals that Fe-ONC exhibits a higher abundance of oxidized species. The Fe of Fe-ONC exists in the form of Fe 3 O 4 particles and Fe-N x , respectively, which are uniformly distributed in the NC. The even spread of iron sites and the plentiful presence of oxygen-rich species are key factors in the superior ORR efficiency of Fe-ONC. Fe-ONC's half-wave potential (E 1/2 ) in an alkaline environment (0.1 M KOH) stands at 0.891 V, markedly surpassing the standard commercial Pt/C value (0.840 V). Additionally, Fe-ONC demonstrated enhanced longevity and resistance to ethanol in comparison to commercially available Pt/C. Fe-ONC's outstanding efficacy highlights its potential as an alternative to precious metal catalysts. The document outlines a plan for creating ORR catalytic materials that are sustainable, economical, and efficient.
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JOURNAL OF POWER SOURCES
·
2019
·
IF 7.467
Qiulin Li,Heng Liu,Long-Cheng Zhang,Hao Chen,Hongjiu Zhu,Yuanke Wu,Maowen Xu,Shu-Juan Bao
Fe-N and pyridinic-N generally are considered the active sites of Fe-N-C catalyst. In this featured work, small uniform Fe/N-rich polymer spheres are selected to prepare the Fe-N-C catalyst and study how the sintering atmosphere (NH 3 , Ar, and H 2 ) to engineer their products. The findings reveal that the sintering atmosphere greatly affected not only the composition , aggregate state, and morphology of Fe, but also the graphitization degree and pore structure of carbon. In addition, XPS results suggest that Fe-N-C-NH 3 possesses the highest Fe-N and pyridinic-N content. Combining its abundant pores, high graphitization, and large specific surface area, the catalyst obtained in NH 3 atmosphere delivers best ORR catalytic performance (E 0 = 0.97 V, E 1/2 = 0.85 V vs RHE), which is even comparable to commercial Pt/C (E 0 = 0.97 V, E 1/2 = 0.83V vs RHE). Moreover, the catalyst exhibits greater stability and methanol resistance than those of Pt/C.
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高影响因子
ANALYTICAL CHEMISTRY
·
2019
·
IF 6.35
Lei Jiao,Weiqing Xu,Hongye Yan,Yu Wu,Chunrong Liu,Dan Du,Yuehe Lin,Chengzhou Zhu
Recently, in situ detection of hydrogen peroxide (H2O2) generated from live cells have caused tremendous attention, because it is of great significance in the control of multiple biological processes. Herein, Fe–N–C single-atom nanozymes (Fe–N–C SAzymes) with intrinsic peroxidase-like activity were successfully prepared via high-temperature calcination using FeCl2, glucose, and dicyandiamide as precursors. The Fe–N–C SAzymes with FeNx as active sites were similar to natural metalloproteases, which can specifically enhance the peroxidase-like activity rather than oxidase-like activity. Accordingly, owing to the excellent catalytic efficiency of the Fe–N–C SAzymes, colorimetric biosensing of H2O2 in vitro was performed via a typical 3,3′,5,5′-tetramethylbenzidine induced an allochroic reaction, demonstrating the satisfactory specificity and sensitivity. With regard to the practical application, in situ detection of H2O2 generated from the Hela cells by the Fe–N–C SAzymes was also performed, which can expand the applications of the newborn SAzymes.
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ChemCatChem
·
2025
·
IF 3.9
Xinquan Wu,Zhen Sun,Hao Li,Xiaolei Guo,Zhen-Feng Huang,Ruijie Gao,Chengxiang Shi,Xiangwen Zhang,Lun Pan,Ji-Jun Zou
Platinum-based catalysts are highly effective for the oxygen reduction reaction (ORR), but their prohibitive cost and insufficient activity impede large-scale commercialization. Herein, we report a Pt@Fe-NC electrocatalyst synthesized by depositing uniform platinum nanoparticles onto an iron–nitrogen–carbon (Fe–NC) support via an ethylene glycol reduction method. The Fe–NC support, prepared from an iron (II)-1,10-phenanthroline complex precursor to ensure high iron utilization, modulates the electronic structure of the Pt nanoparticles, thereby enhancing both catalytic activity and stability. The optimized Pt@Fe-NC catalyst (13.54 wt% Pt) exhibits exceptional ORR performance in acidic media, with a half-wave potential of 0.852 V and notable stability. When integrated into a zinc-air battery, the catalyst delivered a high specific capacity of 652.66 mAh g Zn −1 . Furthermore, a proton exchange membrane fuel cell (PEMFC) employing this catalyst achieved a high open-circuit voltage (OCV) of 0.964 V and a peak power density of 1.722 W cm −2 , outperforming most previously reported Pt-based catalysts. This study highlights a synergistic strategy between Pt nanoparticles and metal-nitrogen-carbon (M–N–C) supports to boost ORR performance, presenting a viable path toward advanced, cost-effective catalysts for energy conversion devices like PEMFCs and zinc-air batteries. Graphical A method of preparing Fe–NC loaded Pt nanoparticle catalysts is presented. The method is used to prepare Fe–NC substrate by loading iron complexes with 1,10-phenanthroline on carbon black and then Pt nanoparticles obtained by ethylene glycol reduction method are loaded on the Fe–NC substrate. The results show that the enhanced activity of the Pt@Fe-NC catalyst is due to the modification of the electronic structure of Fe on Pt in the Fe-NC support.
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Journal of the American Chemical Society
·
2022
·
IF 16.383
Fei Xiao,Yian Wang,Gui-Liang Xu,Fei Yang,Shangqian Zhu,Cheng-Jun Sun,Yingdan Cui,Zhiwen Xu,Qinglan Zhao,Juhee Jang,Xiaoyi Qiu,Ershuai Liu,Walter S. Drisdell,Zidong Wei,Meng Gu,Khalil Amine,Minhua Shao
The poor durability of Pt-based nanoparticles dispersed on carbon black is the challenge for the application of long-life polymer electrolyte fuel cells. Recent work suggests that Fe- and N-codoped carbon (Fe–N–C) might be a better support than conventional high-surface-area carbon. In this work, we find that the electrochemical surface area retention of Pt/Fe–N–C is much better than that of commercial Pt/C during potential cycling in both acidic and basic media. In situ inductively coupled plasma mass spectrometry studies indicate that the Pt dissolution rate of Pt/Fe–N–C is 3 times smaller than that of Pt/C during cycling. Density functional theory calculations further illustrate that the Fe–N–C substrate can provide strong and stable support to the Pt nanoparticles and alleviate the oxide formation by adjusting the electronic structure. The strong metal–substrate interaction, together with a lower metal dissolution rate and highly stable support, may be the reason for the significantly enhanced stability of Pt/Fe–N–C. This finding highlights the importance of carbon support selection to achieve a more durable Pt-based electrocatalyst for fuel cells.
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Journal of Materials Chemistry A
·
2014
·Vol. 2
·期 30
·11768-11775
·
IF 0
Yi Yao,Hui Xiao,Peng Wang,Panpan Su,Zhigang Shao,Qihua Yang
The development of non-precious metal catalysts for oxygen reduction reactions (ORRs) is of extreme importance for the construction of efficient H2/O2 polymer electrolyte membrane fuel cells (PEMFCs), one of the most promising clean energy technologies. Herein, we report the fabrication of core–shell structured CNTs@Fe–N–C composites with a Fe–N–C shell closely wrapped around a core of CNTs (carbon nanotubes) as efficient catalysts for ORR. CNTs@Fe–N–C composites afford comparable activity to commercial Pt/C catalysts with a loading of 20 μg Pt cm−2 towards ORR in alkaline media. The results of XRD, TEM, XPS and 57Fe Mössbauer characterizations suggest that the high ORR activity of CNTs@Fe–N–C composites are mainly attributed to the combined advantages of the unique core–shell nanostructure allowing close contact between Fe–N–C and CNTs, uniformly distributed FeN4/C species, and the presence of pyridine and graphitic nitrogen.
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Fuel Cells
·
2022
·
IF 2.948
Yanqi Hao,Lin Ge,Siew Hwa Chan
Looking for non-noble metal catalysts with low cost, high activity, and high stability to replace platinum in oxygen reduction reaction (ORR) has aroused great concern. According to previous studies, Fe-N x /C material is one of the most promising non-noble metal catalysts for ORR. In this study, new Fe-N x /C material was synthesized by introducing CeO 2 and Fe 3 O 4 nanoparticles into a Fe-N x /C material derived from ZIF-8 as precursors. The new material was called CeO 2 -Fe 3 O 4 @Fe-N/C catalyst and the activity of the catalyst was found to be significantly improved in 0.1 mol L −1 KOH. The half-wave potential of CeO 2 -Fe 3 O 4 @Fe-N/C (0.892 V) is higher than that of Pt/C by 67 mV. In the stability test, the half-wave potential of CeO 2 -Fe 3 O 4 @Fe-N/C was only reduced by 4 mV after 5,000 cycles. The high performance is attributed to the introduction of CeO 2 and Fe 3 O 4 , which gives CeO 2 -Fe 3 O 4 @Fe-N/C enhanced electrocatalytic activity and long-term stability. This approach makes CeO 2 -Fe 3 O 4 @Fe-N/C a promising candidate for cathode catalysts in renewable energy conversion devices.
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高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2025
·
IF 8.3
Ruina Li,Xuwen Li,Qingcheng Liu,Hua Yue,Yang Meng,Yuanyuan Tian
With the continuous advancement of fuel cell technology, the exploration and development of highly efficient non - precious - metal catalysts for the oxygen reduction reaction (ORR) have emerged as a focal point of research. Fe–N–C catalysts have attracted much attention due to their excellent performance and low cost, and coupling single-atom catalysts (SACs) with atomic clusters (ACs) is an effective method to improve catalyst activity. This study used the pyrolysis method to synthesize iron atom catalysts (Fe–N–C SACs) and iron cluster coupled catalysts (Fe–N–C SACs/ACs) on ZIF-8 carbon support. It evaluated the catalyst performance through electrochemical testing. The experimental results showed that the introduction of Fe clusters improved the half-wave potential of the catalyst to 0.399 V, which represented an 8.2 % enhancement compared to the SAC catalyst and reached 87.1 % of that of the commercial Pt–C catalyst, and reduced the Tafel slope to 61.47 mV dec −1 , effectively improving the ORR activity of the catalyst. We constructed FeN 4 single atom catalyst models and FeN 4 /Fe 4 N 6 single atom cluster catalyst models using density functional theory (DFT), analyzed their electronic structures and reaction mechanisms, and revealed the mechanism of action of iron clusters. DFT calculations showed that iron clusters altered the charge distribution of FeN 4 sites, reducing the rate determining step (RDS) (OH desorption) energy to 0.5 eV, which promoted the desorption of products and the re-adsorption of reactants. As a result, the superior electrocatalytic performance of Fe–N–C SAC/AC is attributed to the synergistic effect between iron clusters and single atoms, which is influenced by the coordination environment and provides new ideas for designing efficient ORR catalysts.
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ChemElectroChem
·
2020
·Vol. 7
·期 7
·1775-1780
·
IF 4.154
Xinyue Zhang,Qingtao Liu,Jianglan Shui
Graphical Balancing act : Polytetrafluoroethylene (PTFE) is added to different positions of the Fe−N−C catalyst layer by using three methods to adjust its hydrophobicity. An appropriate amount of PTFE in the Fe−N−C catalyst layer is beneficial to the power density of the PEM fuel cell. However, the hydrophobicity of the Fe−N−C catalyst layer does not affect the long-term durability of the fuel cells, although high hydrophobicity will improve the fuel cell initial durability. The hydrophobicity of the cathode catalyst layer (CCL) affects the performance of the proton exchange membrane fuel cell (PEMFC) by adjusting the water management of the catalyst layer, which has been extensively studied in Pt-based catalysts. Here, the effect of the hydrophobicity of Fe−N−C CCL on the performance of the PEMFC is investigated. The hydrophobicity of the Fe−N−C CCL is tuned by polytetrafluoroethylene (PTFE) by using three addition methods: 1) coat PTFE on Fe−N−C powder and heat-treat; 2) mix PTFE emulsion with Fe−N−C ink and then brush the electrode; and 3) transfer a ground PTFE/Fe−N−C composite film onto the gas diffusion layer by the decal method. For each PTFE addition method, the optimized PTFE amount can increase the power density of Fe−C−N PEMFC by 15.1 %, 26.6 %, and 87.2 %, respectively. At the same time, it is found that enhanced hydrophobicity reduces the initial current decay rate of the Fe−N−C CCLs, but their residual current densities are close after a 50 h durability test at 0.5 V in a H 2 -O 2 PEMFC. It can be concluded that the hydrophobicity of the Fe−N−C CLL has a great influence on the power density of the fuel cell, but the influence on the long-term durability of the fuel cell is negligible.
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Nano Research
·
2020
·Vol. 13
·期 9
·2420-2426
·
IF 8.183
Luo Ergui,Wang Chen,Li Yang,Wang Xian,Gong Liyuan,Zhao Tuo,Jin Zhao,Ge Junjie,Liu Changpeng,Xing Wei
Fe/N/C material is the most competitive alternative to precious-metal catalysts for oxygen reduction. In view of the present consensus on active centers, further effort is directed at maximizing the density of single Fe atoms. Here, the imperfections in commonly used doping strategy of Fe for the synthesis of zeolitic imidazolateframework (ZIF)-derived Fe/N/C catalysts are revealed. More importantly, a strikingly improved catalyst is obtained by a ‘second pyrolysis’ method and delivers a half-wave potential of 0.825 V (vs. RHE) in acidic media. The strong confinement effect of carbonaceous host accounts for the formation of dense single-atom sites and thus the high activity. Our findings will potentially facilitate future improvement of M/N/C catalysts.
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