Atomic Manipulation to Create High-Valent Fe<sup>4+</sup> for Efficient and Ultrastable Oxygen Evolution at Industrial-Level Current Density
Yong Feng, Huan Wang, Kun Feng, Chengyu Li, Shuo Li, Cheng Lü, Youyong Li, Ding Ma, Jun Zhong
Abstract
Manipulating the electronic structure of a catalyst at the atomic level is an effective but challenging way to improve the catalytic performance. Here, by stretching the Fe–O bond in FeOOH with an inserted Mo atom, a Fe–O–Mo unit can be created, which will induce the formation of high-valent Fe 4+ during the alkaline oxygen evolution reaction (OER). The highly active Fe 4+ state has been clearly revealed by in situ X-ray absorption spectroscopy, which can both enhance the oxidation capability and lead to an efficient and stable adsorbate evolution mechanism (AEM) pathway for the OER. As a result, the obtained Fe–Mo–Ni 3 S 2 catalyst exhibits both superior OER activity and outstanding stability, which can achieve an industrial-level current density of 1 A cm –2 at a low overpotential of 259 mV (at 60 °C) and can stably work at the large current for more than 2000 h. Moreover, by coupling with commercial Pt/C, the Fe–Mo–Ni 3 S 2 ∥Pt/C system can be used in the anion exchange membrane cell to acquire 1 A cm –2 for overall water splitting at 1.68 V (2.03 V for 4 A cm –2 ), outperforming the benchmark RuO 2 ∥Pt/C system. The efficient, low-cost, and ultrastable OER catalyst enabled by manipulating the atomic structure may provide potential opportunities for future practical water splitting.