title: Electrocatalytic Cobalt Nanoparticles Interacting with Nitrogen-Doped Carbon Nanotube in Situ Generated from a Metal-Organic Framework for the Oxygen Reduction Reaction.
abstract: A metal organic framework (MOF), synthesized from cobalt salt, melamine (mela), and 1,4-dicarboxybezene (BDC), was used as precursor to prepare Co/CoNx/N-CNT/C electrocatalyst via heat treatment at different temperature (700-900 °C) under nitrogen atmosphere. Crystallites size and microstrain in the 800 °C heat-treated sample (MOFs-800) were the lowest, whereas the stacking fault value was the highest among the rest of the homemade samples, as attested to by the Williamson-Hall analysis, hence assessing that the structural or/and surface modification of Co nanoparticles (NPs), found in MOFs-800, was different from that in other samples. CNTs in MOFs-800, interacting with Co NPs, were formed on the surface of the support, keeping the hexagonal shape of the initial MOF. Among the three homemade samples, the MOF-800 sample, with the best electrocatalytic performance toward oxygen reduction reaction (ORR) in 0.1 M KOH solution, showed the highest density of CNTs skin on the support, the lowest ID/IGratio, and the largest N atomic content in form of pyridinic-N, CoNx, pyrrolic-N, graphitic-N, and oxidized-N species. Based on the binding energy shift toward lower energies, a strong interaction between the active site and the support was identified for MOFs-800 sample. The number of electron transfer was 3.8 on MOFs-800, close to the value of 4.0 determined on the Pt/C benchmark, thus implying a fast and efficient multielectron reduction of molecular oxygen on CoNxactive sites. In addition, the chronoamperometric response within 24 000 s showed a more stable current density at 0.69 V/RHE on MOFs-800 as compared with that of Pt/C.
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , No. 15 Beisanhuan East Road, Beijing 100029, China.
authors.forename: Haihong
authors.initials: H
authors.lastname: Zhong
authors.affiliation: New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Center , Guangzhou, Guangdong 510006, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , No. 15 Beisanhuan East Road, Beijing 100029, China.
authors.forename: Shi
authors.initials: S
authors.lastname: He
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , No. 15 Beisanhuan East Road, Beijing 100029, China.
authors.forename: Pinggui
authors.initials: P
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , No. 15 Beisanhuan East Road, Beijing 100029, China.
authors.forename: Dianqing
authors.initials: D
authors.lastname: Li
authors.affiliation: IC2MP, UMR-CNRS 7285, University of Poitiers , F-86022 Poitiers, France.
authors.forename: Nicolas
authors.identifier: http://orcid.org/0000-0002-6311-9258
authors.initials: N
authors.lastname: Alonso-Vante
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , No. 15 Beisanhuan East Road, Beijing 100029, China.
authors.forename: Yongjun
authors.identifier: http://orcid.org/0000-0001-9254-6219
authors.initials: Y
authors.lastname: Feng
keywords: cobalt nanoparticles; metal−organic framework; nitrogen-doped carbon nanotube; nonprecious metal electrocatalysts; oxygen reduction reaction