Co@Co₃O₄ core–shell particle encapsulated N-doped mesoporous carbon cage hybrids as active and durable oxygen-evolving catalysts

Abstract

Cobalt-based nanomaterials are promising candidates as efficient, affordable, and sustainable alternative electrocatalysts for the oxygen evolution reaction (OER). However, the catalytic efficiency of traditional nanomaterials is still far below what is expected, because of their low stability in basic solutions and poor active site exposure yield. Here a unique hybrid nanomaterial comprising Co@Co3O4 core-shell nanoparticle (NP) encapsulated N-doped mesoporous carbon cages on reduced graphene oxide (denoted as Co@Co3O4@NMCC/rGO) is successfully synthesized via a carbonization and subsequent oxidation strategy of a graphene oxide (GO)-based metal-organic framework (MOF). Impressively, the special carbon cage structure is very important for not only leading to a large active surface area, enhanced mass/charge transport capability, and easy release of gas bubbles, but also preventing Co@Co3O4 NPs from aggregation and peeling off during prolonged electrochemical reactions. As a result, in alkaline media, the resulting hybrid materials catalyze the OER with a low onset potential of ∼1.50 V (vs. RHE) and an over-potential of only 340 mV to achieve a stable current density of 10 mA cm(-2) for at least 25 h. In addition, metallic Co cores in Co@Co3O4 provide an alternative way for electron transport and accelerate the OER rate.

Zeolitic Imidazolate Framework-Mediated Synthesis of Co3O4 Nanoparticles Encapsulated in N-Doped Graphitic Carbon as an Efficient Catalyst for Selective Oxidation of Hydrocarbons

“…26 Ma and co-workers demonstrated a facile synthesis strategy of Co@Co 3 O 4 encapsulated N-doped mesoporous carbon cages on reduced graphene oxide (r-GO) as an active oxygen-evolving catalyst. 27 A special attention has been directed towards graphene oxide with a unique two-dimensional structure and excellent electrical conductivity as a promising candidate of catalytic support. 4 We employ the self assembly strategy of ZIF-9 and graphene oxide (GO) via electrostatic attraction to form a carbon-based composite material, which upon carbonization route at high temperature under inert atmosphere was adopted to encapsulate novel Co 3 analysis, scanning electron microscopy (SEM) with the corresponding elemental mapping, Co K-edge X-ray absorption fine structure (XAFS), Raman and X-ray photoelectron spectroscopy (XPS) studies.…”

Iron–Cobalt Phosphomolybdate with High Electrocatalytic Activity for Oxygen Evolution Reaction

“…The peaks at 797.4 and 795.8 eV in the Co 2 p XPS spectrum are assinged to the spin‐orbit doublets of Co 2+ ions, and the peaks at 781.2 and 780.3 eV are ascribed to the spin‐orbit doublets of Co 3+ ions. The satellite peaks of Co 2 p appear at around 805.7 and 790.0 eV (Figure b) . For the O 1 s XPS spectrum (Figure d), the peaks at around 532.8 and 531.4 eV are attributed to the bound hydroxide groups and structural water in the catalyst, respectively .…”

“…The satellite peaks of Co 2p appear at around8 05.7 and 790.0 eV (Figure 8b). [51,52] For the O1 sX PS spectrum ( Fig-ure 8d), the peaks at around 532.8 and 531.4 eV are attributed to the bound hydroxidegroups and structural water in the catalyst, respectively. [53] The shoulders at 529.6 and 530.4 eV can be assigned to the CoÀOi nteraction owing to as mall degree of dehydroxylation duringt he drying process.…”

Experimental and theoretical investigations of the effect of heteroatom-doped carbon microsphere supports on the stability and storage capacity of nano-Co3O4 conversion anodes for application in lithium-ion batteries

“…2e) with four deconvoluted peaks at 398.5 eV, 399.7 eV, 400.7 eV and 401.6 eV could be attributed to the presence of pyridinic N, pyrrolic N, quaternary-graphitic N and oxidized species respectively. 52 The surface and structural morphology of the as-prepared materials was observed by scanning electron microscopy (SEM), and the images are shown in Fig. 3.…”