A review of oxygen reduction mechanisms for metal-free carbon-based electrocatalysts

Abstract

The sluggish kinetics of Oxygen Reduction Reaction (ORR) at the cathode in proton exchange membrane fuel cells or metal-air batteries requires highly effective and stable electrocatalysts to boost the reaction. The low abundance and high price of Pt-based electrocatalysts hamper the widespread application of proton exchange membrane fuel cells and metal-air batteries. As promising alternatives, metal-free carbon materials, especially upon doping heteroatoms or creating defects demonstrated excellent ORR activity, which is as efficient as or even superior to commercial platinum on carbon. Significant progress on the development of advanced carbon materials as highly stable and durable catalysts has been achieved, but the catalytic mechanisms of these materials still remain undistinguished. In present review, we summarized the up-to-date progress in the studies of carbon materials, and emphasized on the combination of experiment and theory to clarify the underlying mechanisms of these materials. At last, we proposed the perspectives on the proper strategies of elucidating the mechanisms of carbon materials as electrocatalysts towards ORR.npj Computational Materials (2019) 5:78 ; https://doi.

N‐Doped Graphene Supported on Metal‐Iron Carbide as a Catalyst for the Oxygen Reduction Reaction: Density Functional Theory Study

“…As a result, there have been many attempts to search for new ORR catalysts based on earth‐abundant elements such as heteroatom (N, B, P, and S)‐doped carbon materials or metal−nitrogen−carbon (M−N−C) catalysts with nonprecious metals such as Fe and Co . Fe−N−C catalysts have been synthesized and exhibit ORR activity comparable to that of Pt‐based catalysts, and the FeN 4 structure embedded within the carbon basal plane has been proposed as the active site .…”

Topological Engineering of Pt‐Group‐Metal‐Based Chiral Crystals toward High‐Efficiency Hydrogen Evolution Catalysts

“…Pt‐group metals, especially Pt, are ideal catalysts for various heterogeneous catalysis such as electrochemical HER. These metals are located near the top of the HER volcano plot with favorable Gibbs‐free energy for hydrogen adsorption, thus exhibiting the state‐of‐the‐art high efficiency 9–12. Recent studies have confirmed that the performance of these metals can be optimized by employing strategies such as nanostructuring, defect introduction, or use of single‐atom catalysts 6,13…”

Porous Nitrogen‐Doped Carbons as Effective Catalysts for Oxygen Reduction Reaction Synthesized from Cellulose and Polyamide

“…It is widely accepted that doping of N atoms into carbon framework is useful to boost the ORR activity. However, which type of the N‐group that makes the main contribution is still not clearly confirmed . Either pyridinic N or graphitic N was regarded as the active sites, whereas some studies suggested that both graphitic N and pyridinic N were responsible for positive onset potential and high current density .…”