Highly Active Atomically Dispersed Co–N_x Sites Anchored on Ultrathin N-Doped Carbon Nanosheets with Durability Oxygen Reduction Reaction of Zinc–Air Batteries

Abstract

Highly efficient and low-cost oxygen reduction reaction electrocatalysts play key roles in the development of advanced energy conversion and storage devices, such as fuel cells and metal–air batteries. Herein, a facile strategy of synthesizing cobalt single atoms anchored on an ultrathin N-doped carbon nanosheet electrocatalyst (marked as CoSAs/N-CNS) via an in situ g-C3N4 template strategy was reported. Impressively, benefiting from highly active Co–Nx sites and highly porous and ultrathin nanosheet morphology which has rich edges and more three-phase boundaries, the as-synthesized CoSAs/N-CNS exhibits markedly enhanced ORR activities under alkaline conditions with half-wave potential (E 1/2) as high as 0.91 V vs RHE, as well as durability of ∼67 h. Furthermore, compared with Pt/C, the CoSAs/N-CNS-based Zn–air battery presents outstanding discharge–charge performance, larger power density of 157.7 mW cm–2, and robust durability with a slight decay after 150 h (900 cycles). The experimental and theoretical results fully show the advantages of CoSAs/N-CNS, which also provides a new insight for the design and development of high-performance atomically dispersed metal active site electrocatalysts toward ORR.

Ultrathin Two-Dimensional Bimetal–Organic Framework Nanosheets as High-Performance Electrocatalysts for Benzyl Alcohol Oxidation

“…In addition, the LSV curves of 2D NiCo-61-MOF at different rotation rates are shown in Figure S6. It could be obviously observed that with the rotation rate increasing, the current density had no obvious change, and the I –1 hardly changed with the change of ω –1 , which confirmed that the EBO was mainly dependent on the electrode kinetics. , These results suggested that Ni sites may present higher activity than the Co site in 2D MOF, which significantly contributed to the kinetics current. The Co 2+ -added optimized electron structure showed a highly active Ni site.…”

Understanding the mechanism and synergistic interaction of cobalt-based electrocatalysts containing nitrogen-doped carbon for 4 e− ORR

“…The incorporation of isolated cobalt atoms in N-CNs signicantly improved the catalytic activity with an E 1/2 of 0.91 V and stability up to 67 h compared to NCNs by lowering the E a of the RDS to 0.32 V compared to N-CNS. 102 Xiaojuan Liu and co-workers synthesized a uniformly distributed cobalt single-atom catalyst embedded into hollow carbon spheres. The catalyst exhibited outstanding and improved activity compared to the conventional CoSAs.…”

“…The incorporation of isolated cobalt atoms in N-CNs significantly improved the catalytic activity with an E 1/2 of 0.91 V and stability up to 67 h compared to NCNs by lowering the E a of the RDS to 0.32 V compared to N-CNS. 102…”

Non-precious transition metal single-atom catalysts for the oxygen reduction reaction: progress and prospects

“…This substrate has a high degree of graphitization, a loose porous structure, and abundant edges, which are conducive to the formation of a large number of active sites and mass transport/electron transfer. 115 Fe 1 /d-CN has been obtained by growing another layer of Fe-containing ZIF-8 outside the ZIF-8, followed by pyrolysis. A higher I D / I G value indicates more defects in Fe 1 /d-CN.…”