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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Chem.</journal-id>
<journal-title>Frontiers in Chemistry</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Chem.</abbrev-journal-title>
<issn pub-type="epub">2296-2646</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fchem.2020.617614</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Chemistry</subject>
<subj-group>
<subject>Editorial</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Editorial: Metal/Covalent Organic Frameworks and Their Derivatives for Electrochemical Energy Applications</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" corresp="yes">
<name><surname>Wang</surname> <given-names>Jian-Gan</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="corresp" rid="c001"><sup>&#x0002A;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/819584/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name><surname>Xu</surname> <given-names>Fei</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
<xref ref-type="corresp" rid="c002"><sup>&#x0002A;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/819759/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name><surname>Zhang</surname> <given-names>Yu</given-names></name>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
<xref ref-type="aff" rid="aff4"><sup>4</sup></xref>
<xref ref-type="corresp" rid="c003"><sup>&#x0002A;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/819988/overview"/>
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<aff id="aff1"><sup>1</sup><institution>State Key Laboratory of Solidification Processing, Center for Nano Energy Materials, School of Materials Science and Engineering, Northwestern Polytechnical University and Shaanxi Joint Lab of Graphene (NPU)</institution>, <addr-line>Xi&#x00027;an</addr-line>, <country>China</country></aff>
<aff id="aff2"><sup>2</sup><institution>Department of Inorganic Chemistry, Technische Universit&#x000E4;t Dresden</institution>, <addr-line>Dresden</addr-line>, <country>Germany</country></aff>
<aff id="aff3"><sup>3</sup><institution>School of Mechanical and Power Engineering, East China University of Science and Technology</institution>, <addr-line>Shanghai</addr-line>, <country>China</country></aff>
<aff id="aff4"><sup>4</sup><institution>Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology</institution>, <addr-line>Kowloon</addr-line>, <country>Hong Kong</country></aff>
<author-notes>
<fn fn-type="edited-by"><p>Edited by: Nosang Vincent Myung, University of Notre Dame, United States</p></fn>
<fn fn-type="edited-by"><p>Reviewed by: Seung Woo Lee, Georgia Institute of Technology, United States</p></fn>
<corresp id="c001">&#x0002A;Correspondence: Jian-Gan Wang <email>wangjiangan&#x00040;nwpu.edu.cn</email></corresp>
<corresp id="c002">Fei Xu <email>feixu&#x00040;nwpu.edu.cn</email></corresp>
<corresp id="c003">Yu Zhang <email>yzhang071&#x00040;ecust.edu.cn</email></corresp>
<fn fn-type="other" id="fn001"><p>This article was submitted to Electrochemistry, a section of the journal Frontiers in Chemistry</p></fn></author-notes>
<pub-date pub-type="epub">
<day>11</day>
<month>12</month>
<year>2020</year>
</pub-date>
<pub-date pub-type="collection">
<year>2020</year>
</pub-date>
<volume>8</volume>
<elocation-id>617614</elocation-id>
<history>
<date date-type="received">
<day>15</day>
<month>10</month>
<year>2020</year>
</date>
<date date-type="accepted">
<day>23</day>
<month>11</month>
<year>2020</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x000A9; 2020 Wang, Xu and Zhang.</copyright-statement>
<copyright-year>2020</copyright-year>
<copyright-holder>Wang, Xu and Zhang</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/"><p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p></license>
</permissions>
<related-article id="RA1" related-article-type="commentary-article" xlink:href="https://www.frontiersin.org/research-topics/11787/metalcovalent-organic-frameworks-and-their-derivatives-for-electrochemical-energy-applications" ext-link-type="uri">Editorial on the Research Topic <article-title>Metal/Covalent Organic Frameworks and Their Derivatives for Electrochemical Energy Applications</article-title></related-article>
<kwd-group>
<kwd>metal-organic frameworks</kwd>
<kwd>covalent organic frameworks</kwd>
<kwd>supercapacitors</kwd>
<kwd>Li-Sulfur batteries</kwd>
<kwd>water splitting</kwd>
<kwd>fuel cells</kwd>
</kwd-group>
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<ref-count count="0"/>
<page-count count="2"/>
<word-count count="923"/>
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</front>
<body>
<p>Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have gained extensive research interest in a myriad of electrochemical energy fields. In this Research Topic, we have collected some original research articles and a comprehensive review based on the MOFs/COFs and/or their derivatives for the use in Li-sulfur batteries, supercapacitors, water splitting, as well as fuel cells. These results demonstrate the promising applications of MOFs/COFs and/or their derivatives toward electrochemical energy communities. Specifically, <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.3389/fchem.2020.608133">Hua et al.</ext-link> reported a freestanding V-doped CoP nanosheet array supported on the carbon cloth by a facile cation exchange/phosphorization treatment on a Co-MOF precursor. The as-prepared V-doped CoP could serve as a highly efficient hydrogen evolution reaction (HER) catalyst in both acidic and basic media. It was revealed that the three-dimensional nanoarray architecture enabled a large electrochemical active surface area to expose more active sites for boosting the HER kinetics. The study also demonstrated the great effectiveness of hetero-atoms doping to enhance the intrinsic catalytic activity of CoP by tuning the electronic properties. Impressively, small overpotentials of 88 and 98 mV were required to afford a current density of 10 mA cm<sup>&#x02212;2</sup> in 0.5 M H<sub>2</sub>SO<sub>4</sub> and 1 M KOH electrolytes, respectively. <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.3389/fchem.2020.00719">He et al.</ext-link> employed an interesting &#x0201C;One-for-All&#x0201D; design strategy to purposely prepare hierarchically nanoporous carbon and ZnCo<sub>2</sub>O<sub>4</sub> particles from a single bimetallic Zn/Co-MOF precursor. The as-synthesized carbon and metal oxide samples were utilized as the negative and positive electrodes to construct asymmetric supercapacitors. Notably, the unique nanoporous structure could provide sufficient active interfaces for delivering high specific capacity. The asymmetric configuration further extends the working voltage window to as high as 1.45 V, thus achieving a high energy density of 28.6 Wh/kg at a power density of 100 W/kg and good cycling stability of 87.2% after 5,000 charge-discharge cycles. <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.3389/fchem.2020.584204">Xu et al.</ext-link> reported the design of amide functionalized covalent triazine frameworks (CTFs) as host materials in lithium-sulfur batteries and for liquid-phase dye adsorption. Amide functionalized CTFs (CTF-PO71) were prepared with pigment PO71 bearing amide group as monomer under ionothermal condition with ZnCl<sub>2</sub> as solvent and catalyst. The pore structure and functional groups can be controlled by the amount of ZnCl<sub>2</sub> to monomer ratio. Afterwards, the effect of pore structure and functional groups on the adsorption-based performances were investigated in detail. The results showed that significant improvement of lithium-sulfur battery performance was achieved compared to non-functionalized CTF, benefitting from the promoted entrapment of polysulfide results from cooperative effect of physical confinement by high porosity and the chemisorption resulting from functional groups in CTF-PO71 networks. Meanwhile, dye adsorption performance revealed the crucial role of amide functional groups for chemical interaction and the pore structure for facile access and selective adsorption toward specific dye molecules. As a core component of proton exchange membrane fuel cells (PEMFCs), proton exchange membrane suffers from significant performance challenges prior to the practical implementation. MOFs can accommodate a large number of water molecules and acidic groups due to their high specific surface area; thus providing sufficient receptors for proton transfer. <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.3389/fchem.2020.00694">Liu et al.</ext-link> provided an urgent overview of the recent progress of MOF modified PEM for PEMFCs. In particular, this review presents a detailed discussion on the effect of different types of MOFs, including UiO-series, MIL-series, ZIF-series, and others, on the performance of PEMFCs. Finally, the challenges and perspectives in this field were provided.</p>
<sec id="s1">
<title>Author Contributions</title>
<p>J-GW: writing&#x02014;review and editing. FX: writing&#x02014;editing. YZ: writing. All authors contributed to the article and approved the submitted version.</p>
</sec>
<sec sec-type="COI-statement" id="conf1">
<title>Conflict of Interest</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
</body>
</article>