Engineering Atomically Dispersed FeN4 Active Sites for CO2 Electroreduction

Nadia Mohd Adli; Weitao Shan; Sooyeon Hwang; Widitha Samarakoon; Stavros Karakalos; Yi Li; David A Cullen; Dong Su; Zhenxing Feng; Guofeng Wang; Gang Wu

doi:10.1002/anie.202012329

Engineering Atomically Dispersed FeN₄ Active Sites for CO₂ Electroreduction

Angew Chem Int Ed Engl. 2021 Jan 11;60(2):1022-1032. doi: 10.1002/anie.202012329. Epub 2020 Nov 12.

Authors

Affiliations

¹ Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA.
² Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
³ Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973, USA.
⁴ School of Chemical Biological and Environmental Engineering, Oregon State University, Corvallis, OR, 97331, USA.
⁵ Department of Chemical Engineering, University of South Carolina, Columbia, SC, 29208, USA.
⁶ Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.

PMID: 33002266
DOI: 10.1002/anie.202012329

Abstract

Atomically dispersed FeN₄ active sites have exhibited exceptional catalytic activity and selectivity for the electrochemical CO₂ reduction reaction (CO2RR) to CO. However, the understanding behind the intrinsic and morphological factors contributing to the catalytic properties of FeN₄ sites is still lacking. By using a Fe-N-C model catalyst derived from the ZIF-8, we deconvoluted three key morphological and structural elements of FeN₄ sites, including particle sizes of catalysts, Fe content, and Fe-N bond structures. Their respective impacts on the CO2RR were comprehensively elucidated. Engineering the particle size and Fe doping is critical to control extrinsic morphological factors of FeN₄ sites for optimal porosity, electrochemically active surface areas, and the graphitization of the carbon support. In contrast, the intrinsic activity of FeN₄ sites was only tunable by varying thermal activation temperatures during the formation of FeN₄ sites, which impacted the length of the Fe-N bonds and the local strains. The structural evolution of Fe-N bonds was examined at the atomic level. First-principles calculations further elucidated the origin of intrinsic activity improvement associated with the optimal local strain of the Fe-N bond.

Keywords: CO2 reduction; Fe-N-C catalysts; electrocatalysis; local strain; single-metal sites.

Abstract

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