Synergistic Effect between the Atomically Dispersed Active Site of Fe-N-C and C-S-C for ORR in Acidic Medium
In this occasion, we investigated a sulfur-doped Fe-N-C (Fe/SNC) catalyst with a thiophene-like structure (C-S-C) that reduces the electron localization around the Fe center and improves the interaction with oxygenated species. The observed synergistic effect makes the Fe/SNC catalyst exhibits better ORR activity than sulfur free catalyst (Fe/NC) in 0.5 M H2SO4. The results were published in the journal of Angewandte Chemie International Edition.
Hangjia Shen, Eduardo Gracia- Espino, Jingyuan Ma, Ketao Zang, Jun Luo, Le Wang, Sanshuang Gao, Xamxikamar Mamat, Guangzhi Hu, Thomas Wagberg, and Shaojun Guo.
Angew. Chem. Int. Ed. (2017), DOI: 10.1002/anie.201706602
Various advanced catalysts of sulfur doped Fe-N-C materials have been recently designed for oxygen reduction reaction (ORR), however, the enhanced activity is still controversial and usually attributed to differences in surface area, improved conductivity, or to uncertain synergistic effects. Here, a sulfur-doped Fe-N-C catalyst (denoted as Fe/SNC) derived via a template sacrificing method is presented. The incorporated S gives a thiophene-like structure (C-S-C), reduces the electron localization around the Fe center, improves the interaction with oxygenated species, and therefore facilitates the complete 4e- ORR in acid solution. This synergistic effect makes the Fe/SNC catalyst exhibits much better ORR activity than sulfur free catalyst (Fe/NC) in 0.5 M H2SO4.
Hydrogen sorption is studied on reduced graphene oxides decorated with Pd and Pt. However, the use of noble metals does not improve the hydrogen storage properties. This work is a collaboration with Prof. Alexandr V. Talyzin (Umeå, Sweden), and the results were published in the Microporous and Mesoporous Materials journal.
Alexey Klechikov, Jinhua Sun, Guangzhi Hu, Mingbo Zheng, Thomas Wågberg, Alexandr V.Talyzin.
Microporous and Mesoporous Materials, 250, 27-34 (2017)
Hydrogen sorption by reduced graphene oxides (r-GO) is not found to increase after decoration with Pd and Pt nanoparticles. Treatments of metal decorated samples using annealing under hydrogen or air were tested as a method to create additional pores by effects of r-GO etching around nanoparticles. Increase of Specific Surface Area (SSA) was observed for some air annealed r-GO samples. However, the same treatments applied to activated r-GO samples with microporous nature and higher surface area result in breakup of structure and dramatic decrease of SSA. Our experiments have not revealed effects which could be attributed to spillover in hydrogen sorption on Pd or Pt decorated graphene. However, we report irreversible chemisorption of hydrogen for some samples which can be mistakenly assigned to spillover if the experiments are incomplete.
Three-dimensional carbon nanofiber derived from bacterial cellulose for use in a Nafion matrix on a glassy carbon electrode for simultaneous voltammetric determination of trace levels of Cd(II) and Pb(II)
Carbon nanofibers were prepared by one-step carbonization of bacterial cellulose and used to detect Cd(II) and Pb(II). The detection limits are 0.38 μg·L−1 for Cd(II) and 0.33 μg·L−1 for Pb(II), respectively. The work was developed as a collaboration with Prof. Hu and Prod. Mamat (China). The results are published in the journal of Microchimica Acta.
Danfeng Qin, Shanshuang Gao, Le Wang, Hangjia Shen, Nuerbiya Yalikun, Parviz Sukhrobov, Thomas Wågberg, Yujie Zhao, Xamxikamar Mamat, Guangzhi Hu.
Microchimica Acta, 184, 2759–2766 (2017)
The authors describe the preparation of carbon nanofibers (CNFs) with a three-dimensional network structure by one-step carbonization of bacterial cellulose at 800 °C. The 3D CNFs wrapped with Nafion polymer were cast on a glassy carbon electrode (GCE) which then enables sensitive detection of Cd(II) and Pb(II). Under optimized conditions and at typical stripping peaks of around −0.80 and −0.55 V (vs Ag/AgCl), the electrode exhibits high sensitivity and a wide analytical range of 2–100 μg·L−1 for both Cd(II) and Pb(II). The detection limits are 0.38 μg·L−1 for Cd(II) and 0.33 μg·L−1 for Pb(II), respectively. The modified GCE was successfully employed to the determination of trace amounts of Cd(II) and Pb(II) in both tap water and waste water.
Hierarchical macroporous carbon foam decorated with cobalt oxide nanoparticles exhibit excellent performance for oxygen evolution reaction (OER). The observed electrocatalytic performance is rationalized by the overall 3D macroporous structure and with the firmly integrated CNTs directly grown on the foam. The work is a collaboration with Prof. Mikkola (Umeå, Sweden). The results are published in the journal of Scientific Reports.
Tung Ngoc Pham, Tiva Sharifi, Robin Sandström, William Siljebo, Andrey Shchukarev, Krisztian Kordas, Thomas Wågberg, and Jyri-Pekka Mikkola
Scientific Reports, 7, 6112 (2017) (Download)
Herein we report a 3D heterostructure comprising a hierarchical macroporous carbon foam that incorporates mesoporous carbon nanotubes decorated with cobalt oxide nanoparticles as an unique and highly efficient electrode material for the oxygen evolution reaction (OER) in electrocatalytic water splitting. The best performing electrode material showed high stability after 10 h, at constant potential of 1.7 V vs. RHE (reversible hydrogen electrode) in a 0.1 M KOH solution and high electrocatalytic activity in OER with low overpotential (0.38 V vs RHE at 10 mA cm−2). The excellent electrocatalytic performance of the electrode is rationalized by the overall 3D macroporous structure and with the firmly integrated CNTs directly grown on the foam, resulting in a large specific surface area, good electrical conductivity, as well as an efficient electrolyte transport into the whole electrode matrix concurrent with an ability to quickly dispose oxygen bubbles into the electrolyte. The eminent properties of the three-dimensional structured carbon matrix, which can be synthesized through a simple, scalable and cost effective pyrolysis process show that it has potential to be implemented in large-scale water electrolysis systems.
Nano for Energy group
Comprehensive Study of an Earth-Abundant Bifunctional 3D Electrode for Efficient Water Electrolysis in Alkaline Medium.
ACS Appl. Mater. Interfaces, 2015, 7, 28148
C60/Collapsed Carbon Nanotube Hybrids - A Variant of Peapods.
Nano Lett., 2015, 15 (2), pp 829–834
Fabrication of One-Dimensional Zigzag [6,6]-Phenyl-C61-Butyric Acid Methyl Ester Nanoribbons from Two-Dimensional Nanosheets.
ACS Nano, 2015, 9, 10516
Hierarchical self-assembled structures based on nitrogen-doped carbon nanotubes as advanced negative electrodes for Li-ion batteries and 3D microbatteries.
J. P. Sources, 2015, 279, 581
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J. Phys. Chem. C, 120, 27849 (2016)
Sn/Be Sequentially co-doped Hematite Photoanodes for Enhanced Photoelectrochemical Water Oxidation: Effect of Be2+ as co-dopant.
Sci Rep. 2016; 6: 23183.
Atomistic understanding of the origin of high oxygen reduction electrocatalytic activity of cuboctahedral Pt3Co–Pt core–shell nanoparticles.
Catal. Sci. Technol., 2016, 6, 1393-1401
Photocatalytic reduction of CO2 with H2O over modified TiO2 nanofibers: Understanding the reduction pathway.
Nano Res. (2016) 9: 1956.