Enhancing Defects of N-Doped Carbon Nanospheres Via Ultralow Co Atom Loading Engineering for a High-Efficiency Oxygen Reduction Reaction

Abstract

It is vital to explore sustainable and highly efficient catalysts for the oxygen reduction reaction (ORR) with increasing energy demand. Herein, a cobalt (Co) atom dispersed on an N-doped carbon nanosphere catalyst (denoted as ECo@D) was designed and constructed by a simple precursor-engineering method. The regulation of heteroatoms and Co metal atoms in precursors introduces more defects and thus reduces the degree of graphitization in the catalyst. The high N content of 5.23 at% in the ECo@D catalyst provides abundant N sites to anchor metallic Co atoms, which further increases the defects for enhanced catalytic activity. The obtained ECo@D with an ultralow loading of Co (only 0.041 wt %) exhibits an onset potential of 1.05 V, a limited-diffusion current density of 4.74 mA/cm2, and a half-wave potential of 0.79 V for the ORR under alkaline conditions, comparable to those of commercial Pt/C (1.06 V, 4.58 mA/cm2, and 0.81 V, respectively). Therefore, the synergistic effect of heteroatoms and Co metal atoms is beneficial for tuning the carbon matrix defects, which leads to the improvement of ORR activity. The Koutecky–Levich equation and rotating ring-disk electrode tests reveal a complete four-electron oxygen reduction pathway, impeding hydrogen peroxide generation. Moreover, nearly 93.8% of the current is retained for ECo@D after 10 h stability testing without any morphological structural collapse. Meanwhile, it demonstrates superior tolerance to methanol. Our discovery opens a door to engineering the defects of carbon catalysts through introducing ultralow loading of non-noble metal atoms on substrates.

A Facile “Double‐Catalysts” Approach to Directionally Fabricate Pyridinic NB‐Pair‐Doped Crystal Graphene Nanoribbons/Amorphous Carbon Hybrid Electrocatalysts for Efficient Oxygen Reduction Reaction

“…Additionally, creating geometric defects is another way to increase ORR active sites by exposing more edge structures. [30][31][32] No matter what the number/kind of heteroatoms or the kind of geometric defect are doped into the carbon matrix, lowering electron conductivity as a side effect is inevitable, which more or less increases the energy consumption in the process of energy conversion. [33][34][35] Hence, there are two critical problems to be solved for enhancing catalytic performance in multiheteroatoms-doped carbon catalysts: 1) control the optimal multiheteroatoms configuration in the synthesis, 2) maintaining the inherent excellent electrochemical conductivity of carbon nanomaterials.…”

“…Additionally, creating geometric defects is another way to increase ORR active sites by exposing more edge structures. [ 30–32 ]…”

Iron Carbide Nanoparticles Supported by Nitrogen-Doped Carbon Nanosheets for Oxygen Reduction

“…Electrochemical analyses were performed in the Autolab (AUT88032) electrochemical workstation. All procedures used in electrochemical testing were also referenced from the previously published article …”

High-Level Oxygen Reduction Catalysts Derived from the Compounds of High-Specific-Surface-Area Pine Peel Activated Carbon and Phthalocyanine Cobalt

“…Nowadays, the predominant commercial ORR catalysts are still made of platinum (Pt) and its alloys because of their outstanding properties. However, Pt and its alloys are expensive and scarce in resources, which greatly limits their practical applications [7][8][9].…”