Abstract
The N-doped cobalt-based (Co) bifunctional single atom catalyst (SAC) has emerged as one of the most promising candidates to substitute noble metal-based catalysts for highly efficient bifunctionality. Herein, a facile silica xerogel strategy is elaborately designed to synthesize uniformly dispersed and dense Co-Nx active sites on N-doped highly porous carbon networks (Co-N-C SAC) using economic biomass materials. This strategy promotes the generation of massive mesopores and micropores for substantially improving the formation of Co-Nx moieties and unique network architecture. The Co-N-C SAC electrocatalysts exhibit an excellent bifunctional activity with a potential gap (ΔE) of 0.81 V in alkaline medias, outperforming those of the most highly active bifunctional electrocatalysts. On top of that, Co-N-C SAC also possesses outstanding performance in ZABs with superior power density/specific capacity. This proposed synthetic method will provide a new inspiration for fabricating various high-content SACs for varied applications.
Highlights
The metal–air battery has attracted considerable attention as a promising energy storage system due to its high theoretical energy/power density, reliable safety, and economic viability [1,2,3,4]
In order to produce a high content of Co-Nx moieties in Co-N-C single atom catalyst (SAC) for efficient oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), the pyrolysis of concentrated Co- and N-containing precursors with C source is the most prevailing manipulation for generating adequate active sites; the Co atoms inevitably tend to agglomerate and cluster into Co-based crystals or nanoparticles encapsulated by C, driven by their high surface free energy during thermal treatment
The ORR and OER activity were determined by linear scanning voltammetry (LSV) on an ring disk electrode (RRDE) in an
Summary
The metal–air battery has attracted considerable attention as a promising energy storage system due to its high theoretical energy/power density, reliable safety, and economic viability [1,2,3,4]. In order to produce a high content of Co-Nx moieties in Co-N-C SACs for efficient OERs and ORRs, the pyrolysis of concentrated Co- and N-containing precursors with C source is the most prevailing manipulation for generating adequate active sites; the Co atoms inevitably tend to agglomerate and cluster into Co-based crystals or nanoparticles encapsulated by C, driven by their high surface free energy during thermal treatment. The assembled ZAB using the Co-N-C SACs shows a high open-circuit voltage of 1.49 V, a high-power density of 143.1 mW cm−2 , and high specific capacity (942 mA h g−1 ) at 10 mA cm−2 , surpassing the commercial 20% Pt/C + IrO2 catalyst and most of the non-precious-metal catalysts [47,48,49] This facile strategy, based on biomassderived precursors, can open an avenue for the large-scale commercial production of single-atom catalysts
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