Topological Defects in Metal‐Free Nanocarbon for Oxygen Electrocatalysis

Abstract

A bifunctional graphene catalyst with abundant topological defects is achieved via the carbonization of natural gelatinized sticky rice to probe the underlying oxygen electrocatalytic mechanism. A nitrogen-free configuration with adjacent pentagon and heptagon carbon rings is revealed to exhibit the lowest overpotential for both oxygen reduction and evolution catalysis. The versatile synthetic strategy and novel insights on the activity origin facilitate the development of advanced metal-free carbocatalysts for a wide range of electrocatalytic applications.

Carbon-Based Metal-Free Electrocatalysis for Energy Conversion, Energy Storage, and Environmental Protection

“…Well-defined pore distributions and defects can affect the catalytic activity of carbon-based catalysts [111,112,[119][120][121][122]. In 2015, Jin et al reported a new class of ORR catalysts based on graphene quantum dots supported by graphene nanoribbons with ORR performances comparable to or even better than that of Pt/C electrodes [119].…”

“…The introduction of defects into carbon materials can generate active sites for electrochemical reactions and is proven to be an effective strategy to improve catalytic activities of carbon-based materials for ORR and OER [111,114]. Therefore, defects are also considered to be a good means to achieve the high performance in metal-air batteries.…”

“…In a similar study, a defective porous carbon (PC) material with only carbon and oxygen was synthesized through the carbonization of Zn-MOF (IRMOF-8) at 950 °C, followed by the removal of Zn atoms during the calcination process and exhibited excellent electrocatalytic activity, molecular selectivity, and long-term durability [122]. More recently, metal-free carbon-based ORR/OER catalysts with topological defects were fabricated through the direct carbonization of carbon/nitrogen precursors on MgO templates [111]. These as-obtained defective rich graphene materials consisting of predominantly few-layer thick graphitic carbon sheets with abundant in-plane nanopores (Fig.…”

“…In general, intrinsic defects in nanocarbon structures, including vacancies, voids, Stone-Wales defects, dislocation, and grain boundaries [110][111][112], often result from the absence of certain atoms and/or reconstruction of the lattice, leading to breaks in electron-hole symmetry [113]. These defective regions in graphitic carbon materials, with dangling groups, hydrogen saturation, or reconstruction free from dangling groups, have been widely demonstrated to alter local densities of π-electrons and increase chemical reactivities [114].…”

N, P-dual doped carbon with trace Co and rich edge sites as highly efficient electrocatalyst for oxygen reduction reaction

“…Their micro-electrochemical system can provide direct evidence to prove that the activity of edge sites was higher than that of the basal plane. Guided by this finding, many researchers try to induce more holes to expose more edge sites or different kinds of defects through various methods [27][28][29][30]. Though metal-free carbon based catalysts have been widely researched, their activities still cannot fully satisfy the demand for commercialization.…”