Theoretically Insight into Co and S Pairs Dispersed on N‐Doped Graphene: Promising Bifunctional Electrocatalysts for Oxygen Reduction/Evolution Reactions

Abstract

Single atom catalysts (SACs) are considered as efficient catalysts for hydrogen‐based energy conversion and storage because of their excellent catalytic performance for oxygen evolution reactions (OER) and oxygen reduction reactions (ORR). In the present work, a new concept of SACs is proposed with the capacity to form d‐p orbital hybridization. These computationally designed SACs contain a metal and non‐metal pair embedded in the N‐doped graphene framework (MX@N6). Based on the overpotential evaluation by the first principle theory calculations, CoS@N6 containing Co and S atom pair possessed a low overpotential of 0.37 V/0.29 V when used as a bifunctional ORR/OER catalyst. These overpotentials are much lower than Co@N6 without S atom. The electronic structure analysis revealed that non‐metal atoms of the catalyst can regulate the electronic structure of active metal sites and facilitate the adsorption and charge transfer between intermediates and the catalyst resulting in enhanced catalytic performance. This work demonstrates an alternative way to further improve the catalytic activity of SACs by introducing a non‐metal atom that may shed light on the rational design of advanced SACs for ORR/OER with high efficiency and stability.

Emerging Amorphized Metastable Structures to Break Limitations of 2D Materials for More Promising Electrocatalysis

“…Highly corrugated 2D materials (e.g., waved graphene) should exhibit similar phenomenon with newly formed dangling bond states facilitating binding reactions. Similar bonding of SACs on the dangling bond active site has also been demonstrated with various other 2D materials, such as N doped graphene, − 2D transition metal carbides/carbonitrides (MXenes), − transition metal chalcogenides (TMCs), , and graphdiyne. − However, the challenge of these protocols lies in the limited number of dangling bonds. High energy input of the fabrication is required if dangling bond states are not active enough, while the metal nucleation is also inevitable and the binding strength may not be strong enough to secure robust electrocatalysis .…”