<i>In-Situ</i> Generated High-Valent Iron Single-Atom Catalyst for Efficient Oxygen Evolution.

Zhang, Zhirong; Feng, Chen; Li, Xiangyang; Liu, Chunxiao; Wang, Dongdi; Si, Rui; Yang, Jinlong; Zhou, Shiming et al. · Nano Lett · 2021

basic_science · Level V

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Abstract

Oxygen evolution reaction (OER) plays an important role in renewable energy supplies as the anodic reaction for electrochemical transformation of various chemicals. Iron-based OER catalysts are potential candidates due to their abundance but suffer from poor activity. Here we demonstrate that a single-atom iron catalyst with <i>in</i>-<i>situ</i> generated Fe<sup>4+</sup> centers is highly active toward OER. Only an overpotential of 320 mV was needed to reach 10 mA cm<sup>-2</sup>. The catalyst exhibited an ultrahigh turnover frequency of 0.62 s<sup>-1</sup> at an overpotential of 0.35 V, which is comparable to currently reported transitional-metal based OER catalysts. Experimental and theoretical studies revealed that the valence state of the metal center transferred from Fe<sup>3+</sup> to highly active Fe<sup>4+</sup> prior to the OER process. This transformation was originated from the strong interaction between atomic Fe and carbon support via C-O-Fe bonding, leading to a lower energy barrier of the rate-limiting *OOH formation.