{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T18:51:19Z","timestamp":1774983079520,"version":"3.50.1"},"reference-count":77,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2022,4,14]],"date-time":"2022-04-14T00:00:00Z","timestamp":1649894400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/50006\/2020"],"award-info":[{"award-number":["UIDB\/50006\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UIDP\/50006\/2020"],"award-info":[{"award-number":["UIDP\/50006\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["PTDC\/QUI-ELT\/28299\/2017"],"award-info":[{"award-number":["PTDC\/QUI-ELT\/28299\/2017"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Catalysts"],"abstract":"<jats:p>The smart choice of polyoxometalates (POMs) and the design of POM@carbon-based composites are promising tools for producing active electrocatalysts for both the oxygen reduction (ORR) and the oxygen evolution reactions (OER). Hence, herein, we report the preparation, characterization and application of three composites based on doped, multi-walled carbon nanotubes (MWCNT_N6) and three different POMs (Na12[(FeOH2)2Fe2(As2W15O56)2]\u00b754H2O, Na12[(NiOH2)2Ni2(As2W15O56)2]\u00b754H2O and Na14[(FeOH2)2Ni2(As2W15O56)2]\u00b755H2O) as ORR and OER electrocatalysts in alkaline medium (pH = 13). Overall, the three POM@MWCNT_N6 composites showed good ORR performance with onset potentials between 0.80 and 0.81 V vs. RHE and diffusion-limiting current densities ranging from \u22123.19 to \u22123.66 mA cm\u22122. Fe4@MWCNT_N6 and Fe2Ni2@MWCNT_N6 also showed good stability after 12 h (84% and 80% of initial current). The number of electrons transferred per O2 molecule was close to three, suggesting a mixed regime. Moreover, the Fe2Ni2@MWCNT_N6 presented remarkable OER performance with an overpotential of 0.36 V vs. RHE (for j = 10 mA cm\u22122), a jmax close to 135 mA cm\u22122 and fast kinetics with a Tafel slope of 45 mV dec\u22121. More importantly, this electrocatalyst outperformed not only most POM@carbon-based composites reported so far but also the state-of-the-art RuO2 electrocatalyst. Thus, this work represents a step forward towards bifunctional electrocatalysts using less expensive materials.<\/jats:p>","DOI":"10.3390\/catal12040440","type":"journal-article","created":{"date-parts":[[2022,4,14]],"date-time":"2022-04-14T21:44:06Z","timestamp":1649972646000},"page":"440","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Synergetic Effects of Mixed-Metal Polyoxometalates@Carbon-Based Composites as Electrocatalysts for the Oxygen Reduction and the Oxygen Evolution Reactions"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7174-7262","authenticated-orcid":false,"given":"In\u00eas S.","family":"Marques","sequence":"first","affiliation":[{"name":"REQUIMTE, Departamento de Qu\u00edmica e Bioqu\u00edmica, Faculdade de Ci\u00eancias, Universidade do Porto, 4169-007 Porto, Portugal"}]},{"given":"Bruno","family":"Jarrais","sequence":"additional","affiliation":[{"name":"REQUIMTE, Departamento de Qu\u00edmica e Bioqu\u00edmica, Faculdade de Ci\u00eancias, Universidade do Porto, 4169-007 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3440-8066","authenticated-orcid":false,"given":"Isra\u00ebl-Martyr","family":"Mbomekall\u00e9","sequence":"additional","affiliation":[{"name":"Institut de Chimie Physique, UMR 8000 CNRS, Universit\u00e9 Paris-Saclay, CEDEX, 91405 Orsay, France"}]},{"given":"Anne-Lucie","family":"Teillout","sequence":"additional","affiliation":[{"name":"Institut de Chimie Physique, UMR 8000 CNRS, Universit\u00e9 Paris-Saclay, CEDEX, 91405 Orsay, France"}]},{"given":"Pedro","family":"de Oliveira","sequence":"additional","affiliation":[{"name":"Institut de Chimie Physique, UMR 8000 CNRS, Universit\u00e9 Paris-Saclay, CEDEX, 91405 Orsay, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1753-8678","authenticated-orcid":false,"given":"Cristina","family":"Freire","sequence":"additional","affiliation":[{"name":"REQUIMTE, Departamento de Qu\u00edmica e Bioqu\u00edmica, Faculdade de Ci\u00eancias, Universidade do Porto, 4169-007 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5263-2737","authenticated-orcid":false,"given":"Diana M.","family":"Fernandes","sequence":"additional","affiliation":[{"name":"REQUIMTE, Departamento de Qu\u00edmica e Bioqu\u00edmica, Faculdade de Ci\u00eancias, Universidade do Porto, 4169-007 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,4,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"eaad4998","DOI":"10.1126\/science.aad4998","article-title":"Combining theory and experiment in electrocatalysis: Insights into materials design","volume":"355","author":"Seh","year":"2017","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1061","DOI":"10.1007\/s10008-019-04211-x","article-title":"Advanced carbon electrode for electrochemical capacitors","volume":"23","author":"Kado","year":"2019","journal-title":"J. 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