Optimizing Microenvironment of Asymmetric N,S-Coordinated Single-Atom Fe via Axial Fifth Coordination toward Efficient Oxygen Electroreduction

Longbin Li; Senhe Huang; Rui Cao; Kai Yuan; Chenbao Lu; Bingyu Huang; Xiannong Tang; Ting Hu; Xiaodong Zhuang; Yiwang Chen

doi:10.1002/smll.202105387

Optimizing Microenvironment of Asymmetric N,S-Coordinated Single-Atom Fe via Axial Fifth Coordination toward Efficient Oxygen Electroreduction

Small. 2022 Jan;18(2):e2105387. doi: 10.1002/smll.202105387. Epub 2021 Nov 20.

Authors

Longbin Li¹, Senhe Huang², Rui Cao³, Kai Yuan¹, Chenbao Lu², Bingyu Huang¹, Xiannong Tang¹, Ting Hu⁴, Xiaodong Zhuang², Yiwang Chen^{1

5}

Affiliations

¹ College of Chemistry/Institute of Polymers and Energy Chemistry, Nanchang University, Nanchang, 330031, China.
² The Meso-Entropy Matter Lab, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
³ Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
⁴ School of Materials Science and Engineering, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, China.
⁵ Institute of Advanced Scientific Research (iASR), Key Laboratory of Functional Small Molecules for Ministry of Education, Jiangxi Normal University, Nanchang, 330022, China.

PMID: 34799983
DOI: 10.1002/smll.202105387

Abstract

Single-atom catalysts (SACs) are attractive candidates for oxygen reduction reaction (ORR). The catalytic performances of SACs are mainly determined by the surrounding microenvironment of single metal sites. Microenvironment engineering of SACs and understanding of the structure-activity relationship is critical, which remains challenging. Herein, a self-sacrificing strategy is developed to synthesize asymmetric N,S-coordinated single-atom Fe with axial fifth hydroxy (OH) coordination (Fe-N₃ S₁ OH) embedded in N,S codoped porous carbon nanospheres (FeN/SC). Such unique penta-coordination microenvironment is determined by cutting-edge techonologies aiding of systematic simulations. The as-obtained FeN/SC exhibits superior catalytic ORR activity, and showcases a half-wave potential of 0.882 V surpassing the benchmark Pt/C. Moreover, theoretical calculations confirmed the axial OH in FeN₃ S₁ OH can optimize 3d orbitals of Fe center to strengthen O₂ adsorption and enhance O₂ activation on Fe site, thus reducing the ORR barrier and accelerating ORR dynamics. Furthermore, FeN/SC containing H₂ O₂ fuel cell performs a high peak power density of 512 mW cm^-2 , and FeN/SC based Znair batteries show the peak power density of 203 and 49 mW cm^-2 in liquid and flexible all-solid-state configurations, respectively. This study offers a new platform for fundamentally understand the axial fifth coordination in asymmetrical planar single-atom metal sites for electrocatalysis.

Keywords: Zn air batteries; microenvironment; oxygen electroreduction; penta-coordination; single-atom catalysts.

Abstract

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