LAUSR

Unravelling the intrinsic mechanism of electrocatalytic oxygen evolution reaction (OER) by use of heterogeneous catalysts is highly desirable to develop related energy conversion technologies. Albeit dynamic self-reconstruction of the catalysts during OER is extensively observed, it is still highly challenging to operando probe the reconstruction and precisely identify the true catalytically active components. Here, a new class of OER precatalyst, cobalt oxychloride (Co2 (OH)3 Cl) with unique features that allow a gradual phase reconstruction during OER due to the etching of lattice anion is demonstrated. The reconstruction continuously boosts OER activities. The reconstruction-derived component delivers remarkable performance in both alkaline and neutral electrolytes. Operando synchrotron radiation-based X-ray spectroscopic characterization together with density functional theory calculations discloses that the etching of lattice Cl- serves as the key to trigger the reconstruction and the boosted catalytic performance roots in the atomic-level coordinatively unsaturated sites (CUS). This work establishes fundamental understanding on the OER mechanism associated with self-reconstruction of heterogeneous catalysts.