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/CoN/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 I/I ratio, and the largest N atomic content in form of pyridinic-N, CoN, 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 CoN active 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.

Surfactant‐Assisted Fabrication of Cubic Cobalt Oxide Hybrid Hollow Spheres as Catalysts for the Oxygen Reduction Reaction

“…Additionally, concerning the binding energies of Co 2+ and Co 3+ , the corresponding shift trend is in the order CoO x /C‐600<CoO x /C‐500≈CoO x /C‐700 (cf. Table ), suggesting that the charge transfer between Co‐containing species and carbon matrix in CoO x /C‐600 is stronger than on the other samples, which probably leads to enhancement of ORR activity ,…”

“…The D‐band (1350 cm −1 ) and G‐band (1598 cm −1 ) are individually relevant to the disorder and the crystallinity degree of sp 2 carbon materials, respectively. The band deconvolution, as discussed in previous reports,, the I D /I G ratio values of ca. 1.12, 1.22 and 1.18 for CoO/C‐500, −600 and −700, respectively, indicate a more graphitic degree and a large disordered carbon domain in CoO x /C‐600 ,…”

Design Strategies toward Advanced MOF‐Derived Electrocatalysts for Energy‐Conversion Reactions

“…[42,58,[70][71][72][73] Taking MIL-88B-NH 3 (Fe 3 O(H 2 N-BDC) 3 , H 2 N-BDC = 2-aminoterephtalic acid) for example, Zhao et al prepared well-defined N-doped carbonized nanoparticles (CNPs) by pyrolyzing spindle-like MIL-88B-NH 3 NPs. [42] Notably, unlike IM-based ligands in ZIFs, which already contain N atoms in pyridine/pyrrole configurations, H 2 N-BDC only contains amino-type N atoms.…”

“…As an important alternative to Pt catalysts, MOF-derived materials exhibit remarkable ORR performance in terms of activity, durability, and tolerance to methanol. [24,[32][33][34][38][39][40][41][42][43][44]47,53,[58][59][60][61][62][63][65][66][67][68][69][70][71][72][73][75][76][77]81,83,97,99,[107][108][109] In particular, some newly developed MOF derivatives achieved highly improved activity that is comparable and even superior to Pt catalysts under identical experimental conditions. Table 1 summarizes the catalytic performances of representative MOF-derived electrocatalysts for the ORR.…”

DUT‐58 (Co) Derived Synthesis of Co Clusters as Efficient Oxygen Reduction Electrocatalyst for Zinc–Air Battery

“…These will provide porous architecture, electric conductivity, and rich catalytic active sites, which all help the catalytic performance for ORR. However, previous studies reported Co nanoparticles (NPs) electrocatalysts derived from MOFs have uniform size distribution ranging from 10 to 20 nm . As we know, the smaller particles show a better catalytic performance for ORR because they can provide more catalytic centers and active sites which promote a faster electron and mass transfer process .…”