Atomically Dispersed Binary Co‐Ni Sites in Nitrogen‐Doped Hollow Carbon Nanocubes for Reversible Oxygen Reduction and Evolution

Abstract

materials, [2] and their coupled composites. [3] Among them, TM singleatom catalysts (SACs) have recently emerged as a new type of frontier materials with high activity, stability, and selectivity, rendering the great potential for diverse catalytic systems. [4] The unique electronic structure, maximized atomutilization efficiency, and unsaturated coordination bonds of the active centers in SACs contribute to the enhanced performance. [5] Moreover, recent investigations have demonstrated that the introduction of secondary metal atoms can further enhance the activity of SACs, indicating the promising development of dual-metal SACs. [6] Nevertheless, on the one hand, there is a serious lack of effective strategies to achieve the atomic control of targeted reactive sites comprising binary metal atoms; on the other hand, the identification of the diatomic structure in dual-metal SACs and the deeper functional mechanism of bimetallic atoms for synergistic catalysis are still in their infancy.Owing to the increasing concerns from energy and environmental issues, growing attention has been paid on developing sustainable energy conversion and storage technologies, such as water-splitting electrolyzers, fuel cells, metal-air batteries, etc. [7] However, the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on the electrodes has been proven to With the inspiration of developing bifunctional electrode materials for reversible oxygen electrocatalysis, one strategy of heteroatom doping is proposed to fabricate dual metal single-atom catalysts. However, the identification and mechanism functions of polynary single-atom structures remain elusive. Atomically dispersed binary Co-Ni sites embedded in N-doped hollow carbon nanocubes (denoted as CoNi-SAs/NC) are synthesized via proposed pyrolysis of dopamine-coated metalorganic frameworks. The atomically isolated bimetallic configuration in CoNi-SAs/NC is identified by combining microscopic and spectroscopic techniques. When employing as oxygen electrocatalysts in alkaline medium, the resultant CoNi-SAs/NC hybrid manifests outstanding catalytic performance for bifunctional oxygen reduction/evolution reactions, boosting the realistic rechargeable zinc-air batteries with high efficiency, low overpotential, and robust reversibility, superior to other counterparts and state-of-the-art precious-metal catalysts. Theoretical computations based on density functional theory demonstrate that the homogenously dispersed single atoms and the synergistic effect of neighboring Co-Ni dual metal center can optimize the adsorption/desorption features and decrease the overall reaction barriers, eventually promoting the reversible oxygen electrocatalysis. This work not only sheds light on the controlled synthesis of atomically isolated advanced materials, but also provides deeper understanding on the structure-performance relationships of nanocatalysts with multiple active sites for various catalytic applications.To date, large numbers of low cost and efficie...

Microenvironment modulation of single-atom catalysts and their roles in electrochemical energy conversion

“…In addition, as the synergistic effect of neighboring dual-metal sites helps to optimize the adsorption/desorption of reactive intermediates (Fig. 4, L and M) (107), development of atomically dispersed binary sites on carbon hosts offers another promising way to decrease the overall reaction barrier for OER.…”

Metal–organic framework based bifunctional oxygen electrocatalysts for rechargeable zinc–air batteries: current progress and prospects

“…7A). 92 Unlike single metal atoms and nanoparticles, the bimetallic-N structure (Co-Ni-N) of this material can effectively reduce the energy barrier, and the synergy between Co and Ni accelerates the reaction kinetics, resulting in a low overpotential, high electron transfer number and good stability in 0.1 M KOH. The CoNi-SAs/NC based ZAB shows a discharge specic capacity of 750.9 mA h g Zn À1 , a low charge and discharge voltage gap of 0.82 V and a high round-trip efficiency of 59.4% ( Fig.…”

Arrayed Cobalt Phosphide Electrocatalyst Achieves Low Energy Consumption and Persistent H2 Liberation from Anodic Chemical Conversion

“…1a) [4][5][6]. Tremendous efforts have been focused on improvement in water electrolyzer architecture [7][8][9][10].…”