Pyridinic-N-Dominated Doped Defective Graphene as a Superior Oxygen Electrocatalyst for Ultrahigh-Energy-Density Zn–Air Batteries

Abstract

Identification of catalytic sites for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in carbon materials remains a great challenge. Here, we construct a pyridinic-N-dominated doped graphene with abundant vacancy defects. The optimized sample with an ultrahigh pore volume (3.43 cm3 g–1) exhibits unprecedented ORR activity with a half-wave potential of 0.85 V in alkaline. For the first time, density functional theory results indicate that the quadri-pyridinic N-doped carbon site synergized with a vacancy defect is the active site, which presents the lowest overpotential of 0.28 V for ORR and 0.28 V for OER. The primary Zn–air batteries display a maximum power density of 115.2 mW cm–2 and an energy density as high as 872.3 Wh kg–1. The rechargeable Zn–air batteries illustrate a low discharge–charge overpotential and high stability (>78 h). This work provides new insight into the correlation between the N configuration synergized with a vacancy defect in electrocatalysis.

Self‐Assembled Three‐Dimensional Graphene Aerogel with an Interconnected Porous Structure for Lithium‐Ion Batteries

“…However, random aggregation between individual graphene sheets and overlaying of graphene sheets result in the decline of surface active sites and poor durability ,. Therefore, self‐assembled three‐dimensional graphene aerogel with abundant exposed defects and edges has attracted extensive attention for its unique skeleton . Compared with ordinary graphene sheets, three‐dimensional graphene aerogel possesses unique properties and structural merits such as large surface area, abundant defect sites, high electronic conductivity and multiple electron transfer paths, thus having great potential as anode material for LIBs.…”

Enhancing Oxygen Reduction Reaction Catalytic Activity Using a Sub‐Stoichiometric CaTiO3−δ Additive

“…The obtained results proved a higher catalytic activity for the composite electrode, with respect to pure Pt/C, in terms of electrochemically active surface area, oxygen reduction current density, onset potential and stability.Oxygen electrochemistry plays a key role either in energy conversion or in energy storage, because of its importance in several technologies, such as fuel cells and metal-air batteries, both in acid and alkaline environment. [1][2][3][4] Although Pt/C catalysts are widely used as oxygen electrode, there is the need to find new, efficient, stable and less expensive materials to be used as cathodes. [5][6][7] Considerable efforts in the last decade were addressed to improve the electrochemical oxygen reduction reaction and to reduce Pt loading, in order to achieve lowcost targets.…”

Cobalt‐Embedded N‐Doped Carbon Arrays Derived In Situ as Trifunctional Catalyst Toward Hydrogen and Oxygen Evolution, and Oxygen Reduction

“…However, Co/CNWs (SCN À ) displays severely damaged activity with almost disappeared E 1/2 for ORR, whose ΔE is estimated to be 0.85 V by using E j = 10 -E 3 , where E 3 is the ORR potential corresponding to the current density of 3 mA cm À 2 . As reported, pyridinic N [64,65] and graphitic N [66][67][68] can promote the electrical conductivity and surface wettability of carbon materials, thus working as active species for OER and ORR. According to the deconvolution results of N 1s, the percentage of graphitic N is 19.8 % for Co/CNWs, higher than that of Co/MMCs (13.5 %), which means graphitic N could not be as the main active N species toward OER and ORR here.…”