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Title: Ultrasmall tungsten carbide catalysts stabilized in graphitic layers for high-performance oxygen reduction reaction

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1397983
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Nano Energy
Additional Journal Information:
Journal Volume: 28; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 21:17:33; Journal ID: ISSN 2211-2855
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Guo, Junjie, Mao, Zhe, Yan, Xiaoli, Su, Rui, Guan, Pengfei, Xu, Bingshe, Zhang, Xuefeng, Qin, Gaowu, and Pennycook, Stephen J. Ultrasmall tungsten carbide catalysts stabilized in graphitic layers for high-performance oxygen reduction reaction. Netherlands: N. p., 2016. Web. doi:10.1016/j.nanoen.2016.08.045.
Guo, Junjie, Mao, Zhe, Yan, Xiaoli, Su, Rui, Guan, Pengfei, Xu, Bingshe, Zhang, Xuefeng, Qin, Gaowu, & Pennycook, Stephen J. Ultrasmall tungsten carbide catalysts stabilized in graphitic layers for high-performance oxygen reduction reaction. Netherlands. doi:10.1016/j.nanoen.2016.08.045.
Guo, Junjie, Mao, Zhe, Yan, Xiaoli, Su, Rui, Guan, Pengfei, Xu, Bingshe, Zhang, Xuefeng, Qin, Gaowu, and Pennycook, Stephen J. 2016. "Ultrasmall tungsten carbide catalysts stabilized in graphitic layers for high-performance oxygen reduction reaction". Netherlands. doi:10.1016/j.nanoen.2016.08.045.
@article{osti_1397983,
title = {Ultrasmall tungsten carbide catalysts stabilized in graphitic layers for high-performance oxygen reduction reaction},
author = {Guo, Junjie and Mao, Zhe and Yan, Xiaoli and Su, Rui and Guan, Pengfei and Xu, Bingshe and Zhang, Xuefeng and Qin, Gaowu and Pennycook, Stephen J.},
abstractNote = {},
doi = {10.1016/j.nanoen.2016.08.045},
journal = {Nano Energy},
number = C,
volume = 28,
place = {Netherlands},
year = 2016,
month =
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.nanoen.2016.08.045

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  • Current platinum group metal (PGM)-free carbon nanocomposite catalysts for the oxygen reduction reaction (ORR) in acidic electrolyte often suffer from rapid degradation associated with carbon corrosion due to the use of large amount of amorphoous carbon black supports. Here, we developed a new concept of using freestanding 3D hydrogel to design support-free Fe-N-C catalysts. A 3D polyaniline (PANI)-based hydrogel was used for preparing a new type of single atomic iron site-rich catalyst, which has exhibited exceptionally enhanced activity and stability compared to conventional Fe-N-C catalysts supported on amorphous carbon blacks. The achieved performance metric on the hydrogel PANI-Fe catalysts ismore » one of the best ever reported PGM-free catalysts, reaching a half-wave potential up to 0.83 V vs. RHE and only leaving 30 mV gap with Pt/C catalysts (60 μgPt/cm2) in challenging acidic media. Remarkable ORR stability was accomplished as well on the same catalyst evidenced by using harsh potential cycling tests. The well dispersion of atomic iron into partially graphitized carbon, featured with dominance of micropores and porous network structures, is capable of accommodating increased number of active sites, strengthening local bonding among iron, nitrogen and carbon, and facilitating mass transfer. The 3D polymer hydrogel approach would be a new pathway to advance PGM-free catalysts.« less
  • The mechanism of bulk tungsten carbide catalysts synthesis from WO{sub 3} in CH{sub 4}/H{sub 2} mixtures has been studied using temperature programmed reactions associated with CH{sub 4}/D{sub 2} exchange reaction and in situ X-ray diffraction. Various experimental parameters have been studied such as partial pressures of reactants, heating rate, mass of precursor, or flow rate in order to determine the most important steps occurring during the transformation of WO{sub 3} to WC. It is shown that at temperatures below 900--923 K the diffusion within the solid particles is slow with respect to the rate of reduction of the surface, allowingmore » the carburization of the surface in the presence of a core still partially oxidized. At higher temperatures, the diffusion is rapid, leading to a uniform reduction within the solid. In this case, the surface is continuously replenished in oxygen thus inhibiting the activation of methane and allowing the carburization to proceed only when the solid is deeply reduced. An inhibiting effect of hydrogen pressure on the interaction of methane with the surface has also been evidenced, an effect which excludes the possibility of an independent control of the reduction process from that of carburization. Finally the role of space velocity has also been elucidated.« less