Standing Carbon‐Supported Trace Levels of Metal Derived from Covalent Organic Framework for Electrocatalysis

Abstract

Single atom catalysts (SACs) are receiving increasing interests due to their high theoretical catalytic efficiency and intriguing physiochemical properties. However, most of the synthetic methodologies involve high‐temperature treatment. This usually leads to limited control over the spatial distribution of metal sites and collapse of porous network that result in limited active site exposure. A strategy to construct SAC by using a covalent organic framework as the precursor is reported in this study. The as‐prepared catalyst is mainly composed of standing carbon layers with the presence of edge‐site hosted metal single atoms. Such structure configuration not only allows full site exposure but also endows the metal site with high intrinsic activity. With a trace amount of cobalt loading (0.17 wt%), the nanorice‐shaped catalyst displays promising electrochemical activities toward catalyzing the oxygen reduction reaction in both alkaline and acidic medium. An ultrahigh mass activity of 838 A gCo–1 at 0.9 V is achieved in the acidic electrolyte. This work suggests a new route to design SACs based on covalent organic framework for energy storage and conversion devices.

Multi‐Scale Design of Metal–Organic Framework‐Derived Materials for Energy Electrocatalysis

“…Still, to achieve a better electrocatalytic performance, metal sources are required as the metal‐based phases/sites have been demonstrated more active for electrocatalysis in most cases. COFs incorporated with Co, [ 99 ] Fe, [ 100 ] and Ni [ 101 ] sources have been used to fabricate COF‐derived materials for electrocatalysis. We have discussed the COF‐based materials for electrocatalysis in another review, and the readers may go for it for a broader overview of this area.…”

Molecular Engineering for Bottom-Up Construction of High-Performance Non-Precious-Metal Electrocatalysts with Well-Defined Active Sites

“…(3) Exceptional thermal stabilities of COFs due to covalent interaction can endure harsh postprocessing environment and keep the structure unchanged . (4) As COFs are metal-free crystalline polymers, M–NC SACs derived from COFs need not consider the elemental impurity brought by the support, which is beneficial to characterize and recognize catalytic active roles of M–NC SACs . All of this enables that COFs can also be served as excellent precursors to synthesize highly active M–NC SACs.…”

“…For instance, Sun’s group reported COF-derived Co–NC SAC with isolated Co–N x coordination sites via the direct pyrolysis Co 2+ @COF-300 at 900 °C for 2 h (Figure a) . It was suggested that the single Co atoms were hosted in the edge-site of nanosized standing carbon layers.…”

“…(a) Synthesis route for Co–NC SAC using COF as the precursor. Reproduced with permission from ref . Copyright 2019 Wiley-VCH.…”

“…For instance, Sun's group reported COF-derived Co−NC SAC with isolated Co−N x coordination sites via the direct pyrolysis Co 2+ @COF-300 at 900 °C for 2 h (Figure 12a). 79 It was suggested that the single Co atoms were hosted in the edge-site of nanosized standing carbon layers. The resulting catalyst exhibited superior activity toward ORR in 0.1 M KOH solution with onset potential and half-wave potential of 0.93 and 0.86 V vs RHE, respectively, overwhelming the commercial Pt/C.…”