The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform

Guoxiong Wang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of iron precursor on the activity and stability of PtFe/C catalyst for oxygen reduction reaction
    Journal of Alloys and Compounds, 2020
    Co-Authors: Qi Wang, Hualong Tao, Guoxiong Wang
    Abstract:

    Abstract The stability of iron species in PtFe/C catalyst in acidic medium is a grand challenge to maintain a high activity and stability for oxygen reduction reaction (ORR) via the geometric and electronic effect. Herein, we report that the use of Ammonium Ferric Citrate with a high thermal stability, instead of iron nitrate, greatly improves the stability of iron species in PtFe/C catalyst in acidic medium after high-temperature reduction treatment. The resulting PtFe/C catalyst with Ammonium Ferric Citrate as iron precursor shows much improved activity and stability for ORR than the counterpart using iron nitrate due to enhanced proportion of PtFe alloy in the PtFe/C catalyst.

  • surface functionalization of zif 8 with Ammonium Ferric Citrate toward high exposure of fe n active sites for efficient oxygen and carbon dioxide electroreduction
    Nano Energy, 2017
    Co-Authors: Fan Cai, Guoxiong Wang, Shu Miao, Songhai Xie, Jian Wang, Xinhe Bao
    Abstract:

    Isolated metal-nitrogen sites are highly active to catalyze the oxygen and carbon dioxide electroreduction, however, the limited content of isolated metal-nitrogen sites within carbon matrix urgently requires full exposure of the active sites on the surface for efficient catalysis. Herein, post-synthetic modification strategy is explored to selectively confine Ammonium Ferric Citrate on the surface of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles. After pyrolysis, isolated iron-nitrogen sites are generated and located on the carbon matrix surface. The highly exposed iron-nitrogen sites demonstrate excellent mass activity toward oxygen reduction reaction in acidic medium, outperforming most reported non-noble metal catalysts, and also show superior selectivity and mass activity toward carbon dioxide electroreduction compared to most reported noble metal catalysts.

  • two step pyrolysis of zif 8 functionalized with Ammonium Ferric Citrate for efficient oxygen reduction reaction
    Journal of Energy Chemistry, 2017
    Co-Authors: Fan Cai, Chengcheng Yan, Guoxiong Wang, Xinhe Bao
    Abstract:

    Zeolitic imidazolate frameworks (ZIFs) are widely employed in catalyst synthesis as parental materials for electrochemical energy storage and conversion. Herein, we have demonstrated a facile synthesis of highly efficient catalyst for oxygen reduction reaction in both alkaline and acidic medium, which is derived from ZIF-8 functionalized with Ammonium Ferric Citrate via two-step pyrolysis in Ar and NH3 atmosphere. The results reveal that the catalytic activity improvement after NH3 pyrolysis benefits from mesopore-dominated morphology and high utilization of Fe-containing active sites. The optimum catalyst shows excellent performance in zinc-air battery and polymer electrolyte membrane fuel cell tests.

  • high density iron nanoparticles encapsulated within nitrogen doped carbon nanoshell as efficient oxygen electrocatalyst for zinc air battery
    Nano Energy, 2015
    Co-Authors: Jing Wang, Shu Miao, Haihua Wu, Guoxiong Wang
    Abstract:

    Abstract Exploring highly efficient electrocatalysts toward oxygen reduction and evolution reactions are critical for the development of rechargeable zinc–air batteries. As a novel class of electrocatalyst, transition metal nanoparticles encapsulated within nitrogen-doped carbon have been regarded as competitive alternative to replace noble metal electrocatalysts. Herein, we report successful synthesis of high-density iron nanoparticles encapsulated within nitrogen-doped carbon nanoshell (Fe@N–C) by solid-phase precursor׳s pyrolysis of dicyandiamide and Ammonium Ferric Citrate. The resulting Fe@N–C material shows excellent bifunctionality for ORR and OER in alkaline medium compared to state-of-the-art commercial Pt/C and IrO2, which demonstrates high performance and cycling durability in zinc–air battery as efficient oxygen electrocatalyst.

  • synthesis of fe fe3c nanoparticles encapsulated in nitrogen doped carbon with single source molecular precursor for the oxygen reduction reaction
    Carbon, 2014
    Co-Authors: Jing Wang, Guoxiong Wang, Shu Miao, Xiaole Jiang, Xinhe Bao
    Abstract:

    Abstract Ammonium Ferric Citrate (AFC) was used as a single-source molecular precursor to prepare Fe/Fe 3 C nanoparticles encapsulated in nitrogen-doped carbon by pyrolysis in Ar atmosphere followed by acid-leaching. Comparative studies, using citric acid and Ferric Citrate as the precursors, indicated that the ammonia and Ferric ion in AFC and the pyrolysis temperature affected the composition of iron species and the properties of carbon in AFC-derived materials. Above the pyrolysis temperature of 600 °C, the iron species were Fe/Fe 3 C, and the carbon had a hollow graphitic nanoshell structure in AFC-derived materials. The specific surface area and content of nitrogen element decreased with increasing pyrolysis temperature. The AFC-derived material pyrolyzed at 600 °C had the optimal graphitization degree, specific surface area (489 m 2  g −1 ) and content of nitrogen (1.8 wt.%), thus resulted in the greatest activity for oxygen reduction reaction among the AFC-derived materials pyrolyzed at different temperatures. The AFC-derived material pyrolyzed at 600 °C exhibited improved methanol-resistance ability compared with Pt/C catalyst.

Wenzhong Shen - One of the best experts on this subject based on the ideXlab platform.

  • fe3o4 carbon nanosheets for all solid state supercapacitor electrodes
    ACS Applied Materials & Interfaces, 2016
    Co-Authors: Jiaqi Duan, Wenzhong Shen
    Abstract:

    Fe3O4@carbon nanosheet composites were synthesized using Ammonium Ferric Citrate as the Fe3O4/carbon precursor and graphene oxide as the structure-directing agent under a hydrothermal process. The surface chemical compositions, pore structures, and morphology of the composite were analyzed and characterized by nitrogen adsorption isotherms, TG analysis, FT-IR, X-ray photoelectron energy spectrum, transmission electron microscopy, and scanning electron microscopy. The composites showed excellent specific capacitance of 586 F/g, 340 F/g at 0.5 A/g and 10 A/g. The all-solid-state asymmetric supercapacitor device assembled using carbon nanosheets in situ embedded Fe3O4 composite and porous carbon showed a largest energy density of 18.3 Wh/kg at power density of 351 W/kg in KOH/PVA gel electrolyte. The synergism of high special surface to volume ratio, mesoporous structure, graphene-based conduction paths, and Fe3O4 nanoparticles provided a high surface area of ion-accessibility, high electric conductivity, an...

  • Fe3O4@Carbon Nanosheets for All-Solid-State Supercapacitor Electrodes
    ACS applied materials & interfaces, 2016
    Co-Authors: Huailin Fan, Jiaqi Duan, Ruiting Niu, Wei Liu, Wenzhong Shen
    Abstract:

    Fe3O4@carbon nanosheet composites were synthesized using Ammonium Ferric Citrate as the Fe3O4/carbon precursor and graphene oxide as the structure-directing agent under a hydrothermal process. The surface chemical compositions, pore structures, and morphology of the composite were analyzed and characterized by nitrogen adsorption isotherms, TG analysis, FT-IR, X-ray photoelectron energy spectrum, transmission electron microscopy, and scanning electron microscopy. The composites showed excellent specific capacitance of 586 F/g, 340 F/g at 0.5 A/g and 10 A/g. The all-solid-state asymmetric supercapacitor device assembled using carbon nanosheets in situ embedded Fe3O4 composite and porous carbon showed a largest energy density of 18.3 Wh/kg at power density of 351 W/kg in KOH/PVA gel electrolyte. The synergism of high special surface to volume ratio, mesoporous structure, graphene-based conduction paths, and Fe3O4 nanoparticles provided a high surface area of ion-accessibility, high electric conductivity, an...

  • Fe3O4@Carbon Nanosheets for All-Solid-State Supercapacitor Electrodes
    2016
    Co-Authors: Huailin Fan, Jiaqi Duan, Ruiting Niu, Wei Liu, Wenzhong Shen
    Abstract:

    Fe3O4@carbon nanosheet composites were synthesized using Ammonium Ferric Citrate as the Fe3O4/carbon precursor and graphene oxide as the structure-directing agent under a hydrothermal process. The surface chemical compositions, pore structures, and morphology of the composite were analyzed and characterized by nitrogen adsorption isotherms, TG analysis, FT-IR, X-ray photoelectron energy spectrum, transmission electron microscopy, and scanning electron microscopy. The composites showed excellent specific capacitance of 586 F/g, 340 F/g at 0.5 A/g and 10 A/g. The all-solid-state asymmetric supercapacitor device assembled using carbon nanosheets in situ embedded Fe3O4 composite and porous carbon showed a largest energy density of 18.3 Wh/kg at power density of 351 W/kg in KOH/PVA gel electrolyte. The synergism of high special surface to volume ratio, mesoporous structure, graphene-based conduction paths, and Fe3O4 nanoparticles provided a high surface area of ion-accessibility, high electric conductivity, and the utmost utilization of Fe3O4 and resulted in excellent specific capacitance, outstanding rate capability and cycling life as all-solid-state supercapacitor electrodes

Fan Cai - One of the best experts on this subject based on the ideXlab platform.

  • surface functionalization of zif 8 with Ammonium Ferric Citrate toward high exposure of fe n active sites for efficient oxygen and carbon dioxide electroreduction
    Nano Energy, 2017
    Co-Authors: Fan Cai, Guoxiong Wang, Shu Miao, Songhai Xie, Jian Wang, Xinhe Bao
    Abstract:

    Isolated metal-nitrogen sites are highly active to catalyze the oxygen and carbon dioxide electroreduction, however, the limited content of isolated metal-nitrogen sites within carbon matrix urgently requires full exposure of the active sites on the surface for efficient catalysis. Herein, post-synthetic modification strategy is explored to selectively confine Ammonium Ferric Citrate on the surface of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles. After pyrolysis, isolated iron-nitrogen sites are generated and located on the carbon matrix surface. The highly exposed iron-nitrogen sites demonstrate excellent mass activity toward oxygen reduction reaction in acidic medium, outperforming most reported non-noble metal catalysts, and also show superior selectivity and mass activity toward carbon dioxide electroreduction compared to most reported noble metal catalysts.

  • two step pyrolysis of zif 8 functionalized with Ammonium Ferric Citrate for efficient oxygen reduction reaction
    Journal of Energy Chemistry, 2017
    Co-Authors: Fan Cai, Chengcheng Yan, Guoxiong Wang, Xinhe Bao
    Abstract:

    Zeolitic imidazolate frameworks (ZIFs) are widely employed in catalyst synthesis as parental materials for electrochemical energy storage and conversion. Herein, we have demonstrated a facile synthesis of highly efficient catalyst for oxygen reduction reaction in both alkaline and acidic medium, which is derived from ZIF-8 functionalized with Ammonium Ferric Citrate via two-step pyrolysis in Ar and NH3 atmosphere. The results reveal that the catalytic activity improvement after NH3 pyrolysis benefits from mesopore-dominated morphology and high utilization of Fe-containing active sites. The optimum catalyst shows excellent performance in zinc-air battery and polymer electrolyte membrane fuel cell tests.

Xinhe Bao - One of the best experts on this subject based on the ideXlab platform.

  • surface functionalization of zif 8 with Ammonium Ferric Citrate toward high exposure of fe n active sites for efficient oxygen and carbon dioxide electroreduction
    Nano Energy, 2017
    Co-Authors: Fan Cai, Guoxiong Wang, Shu Miao, Songhai Xie, Jian Wang, Xinhe Bao
    Abstract:

    Isolated metal-nitrogen sites are highly active to catalyze the oxygen and carbon dioxide electroreduction, however, the limited content of isolated metal-nitrogen sites within carbon matrix urgently requires full exposure of the active sites on the surface for efficient catalysis. Herein, post-synthetic modification strategy is explored to selectively confine Ammonium Ferric Citrate on the surface of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles. After pyrolysis, isolated iron-nitrogen sites are generated and located on the carbon matrix surface. The highly exposed iron-nitrogen sites demonstrate excellent mass activity toward oxygen reduction reaction in acidic medium, outperforming most reported non-noble metal catalysts, and also show superior selectivity and mass activity toward carbon dioxide electroreduction compared to most reported noble metal catalysts.

  • two step pyrolysis of zif 8 functionalized with Ammonium Ferric Citrate for efficient oxygen reduction reaction
    Journal of Energy Chemistry, 2017
    Co-Authors: Fan Cai, Chengcheng Yan, Guoxiong Wang, Xinhe Bao
    Abstract:

    Zeolitic imidazolate frameworks (ZIFs) are widely employed in catalyst synthesis as parental materials for electrochemical energy storage and conversion. Herein, we have demonstrated a facile synthesis of highly efficient catalyst for oxygen reduction reaction in both alkaline and acidic medium, which is derived from ZIF-8 functionalized with Ammonium Ferric Citrate via two-step pyrolysis in Ar and NH3 atmosphere. The results reveal that the catalytic activity improvement after NH3 pyrolysis benefits from mesopore-dominated morphology and high utilization of Fe-containing active sites. The optimum catalyst shows excellent performance in zinc-air battery and polymer electrolyte membrane fuel cell tests.

  • synthesis of fe fe3c nanoparticles encapsulated in nitrogen doped carbon with single source molecular precursor for the oxygen reduction reaction
    Carbon, 2014
    Co-Authors: Jing Wang, Guoxiong Wang, Shu Miao, Xiaole Jiang, Xinhe Bao
    Abstract:

    Abstract Ammonium Ferric Citrate (AFC) was used as a single-source molecular precursor to prepare Fe/Fe 3 C nanoparticles encapsulated in nitrogen-doped carbon by pyrolysis in Ar atmosphere followed by acid-leaching. Comparative studies, using citric acid and Ferric Citrate as the precursors, indicated that the ammonia and Ferric ion in AFC and the pyrolysis temperature affected the composition of iron species and the properties of carbon in AFC-derived materials. Above the pyrolysis temperature of 600 °C, the iron species were Fe/Fe 3 C, and the carbon had a hollow graphitic nanoshell structure in AFC-derived materials. The specific surface area and content of nitrogen element decreased with increasing pyrolysis temperature. The AFC-derived material pyrolyzed at 600 °C had the optimal graphitization degree, specific surface area (489 m 2  g −1 ) and content of nitrogen (1.8 wt.%), thus resulted in the greatest activity for oxygen reduction reaction among the AFC-derived materials pyrolyzed at different temperatures. The AFC-derived material pyrolyzed at 600 °C exhibited improved methanol-resistance ability compared with Pt/C catalyst.

Jiaqi Duan - One of the best experts on this subject based on the ideXlab platform.

  • fe3o4 carbon nanosheets for all solid state supercapacitor electrodes
    ACS Applied Materials & Interfaces, 2016
    Co-Authors: Jiaqi Duan, Wenzhong Shen
    Abstract:

    Fe3O4@carbon nanosheet composites were synthesized using Ammonium Ferric Citrate as the Fe3O4/carbon precursor and graphene oxide as the structure-directing agent under a hydrothermal process. The surface chemical compositions, pore structures, and morphology of the composite were analyzed and characterized by nitrogen adsorption isotherms, TG analysis, FT-IR, X-ray photoelectron energy spectrum, transmission electron microscopy, and scanning electron microscopy. The composites showed excellent specific capacitance of 586 F/g, 340 F/g at 0.5 A/g and 10 A/g. The all-solid-state asymmetric supercapacitor device assembled using carbon nanosheets in situ embedded Fe3O4 composite and porous carbon showed a largest energy density of 18.3 Wh/kg at power density of 351 W/kg in KOH/PVA gel electrolyte. The synergism of high special surface to volume ratio, mesoporous structure, graphene-based conduction paths, and Fe3O4 nanoparticles provided a high surface area of ion-accessibility, high electric conductivity, an...

  • Fe3O4@Carbon Nanosheets for All-Solid-State Supercapacitor Electrodes
    ACS applied materials & interfaces, 2016
    Co-Authors: Huailin Fan, Jiaqi Duan, Ruiting Niu, Wei Liu, Wenzhong Shen
    Abstract:

    Fe3O4@carbon nanosheet composites were synthesized using Ammonium Ferric Citrate as the Fe3O4/carbon precursor and graphene oxide as the structure-directing agent under a hydrothermal process. The surface chemical compositions, pore structures, and morphology of the composite were analyzed and characterized by nitrogen adsorption isotherms, TG analysis, FT-IR, X-ray photoelectron energy spectrum, transmission electron microscopy, and scanning electron microscopy. The composites showed excellent specific capacitance of 586 F/g, 340 F/g at 0.5 A/g and 10 A/g. The all-solid-state asymmetric supercapacitor device assembled using carbon nanosheets in situ embedded Fe3O4 composite and porous carbon showed a largest energy density of 18.3 Wh/kg at power density of 351 W/kg in KOH/PVA gel electrolyte. The synergism of high special surface to volume ratio, mesoporous structure, graphene-based conduction paths, and Fe3O4 nanoparticles provided a high surface area of ion-accessibility, high electric conductivity, an...

  • Fe3O4@Carbon Nanosheets for All-Solid-State Supercapacitor Electrodes
    2016
    Co-Authors: Huailin Fan, Jiaqi Duan, Ruiting Niu, Wei Liu, Wenzhong Shen
    Abstract:

    Fe3O4@carbon nanosheet composites were synthesized using Ammonium Ferric Citrate as the Fe3O4/carbon precursor and graphene oxide as the structure-directing agent under a hydrothermal process. The surface chemical compositions, pore structures, and morphology of the composite were analyzed and characterized by nitrogen adsorption isotherms, TG analysis, FT-IR, X-ray photoelectron energy spectrum, transmission electron microscopy, and scanning electron microscopy. The composites showed excellent specific capacitance of 586 F/g, 340 F/g at 0.5 A/g and 10 A/g. The all-solid-state asymmetric supercapacitor device assembled using carbon nanosheets in situ embedded Fe3O4 composite and porous carbon showed a largest energy density of 18.3 Wh/kg at power density of 351 W/kg in KOH/PVA gel electrolyte. The synergism of high special surface to volume ratio, mesoporous structure, graphene-based conduction paths, and Fe3O4 nanoparticles provided a high surface area of ion-accessibility, high electric conductivity, and the utmost utilization of Fe3O4 and resulted in excellent specific capacitance, outstanding rate capability and cycling life as all-solid-state supercapacitor electrodes