Identification of the Origin for Reconstructed Active Sites on Oxyhydroxide for Oxygen Evolution Reaction.

The regulation of atomic and electronic structures of active sites plays an important role upon rational design of oxygen evolution reaction (OER) catalysts toward electrocatalytic hydrogen generation. However, the precise identification of the active sites for surface reconstruction behavior during OER remains elusive for water-alkali electrolysis. Herein, we report irreversible reconstruction behavior accompanied by copper dynamic evolution for cobalt iron layered double hydroxide (CoFe LDH) precatalyst to form CoFeCuOOH active species with high-valent Co species, identifying the origin of reconstructed active sites through operando UV-Visible (UV-Vis), in-situ Raman and X-ray absorption fine-structure (XAFS) spectroscopies. Density functional theory analysis rationalizes this typical electronic structure evolution causes the transfer of intramolecular electron to form ligand holes, promoting reconstruction of active sites. Specifically, unambiguous identification of active sites for CoFeCuOOH is explored by in-situ 18 O isotope-labeling differential electrochemical mass spectrometry (DEMS) and supported by theoretical calculation, confirming mechanism switch to oxygen-vacancy-site mechanism (OVSM) pathway on lattice oxygen. This work enables us to elucidate the vital role of dynamic active-site generation and representative contribution of OVSM pathway for efficient OER performance. This article is protected by copyright. All rights reserved.