Anion Etching for Accessing Rapid and Deep Self-Reconstruction of Precatalysts for Water Oxidation

Transition metal-based nanomaterials represent an emerging class of highly active and low-cost precatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, most OER precatalysts undergo slow or incomplete self-reconstructions to generate real active sites, which is a time-consuming process for achieving high OER performance. Thus, we report a new class of OER precatalysts that can achieve highly active OER species by a rapid and deep self-reconstruction (denoted by SELF-RECON). The precatalysts with a core-shell structure comprising NiMoO4 (core) and NiFe/NiFeOx nanoparticles in N-doped amorphous carbons (shell) (denoted by [email protected]), can realize rapid MoO42− dissolution and fast formation of NiOOH with Fe incorporation simultaneously. In situ Raman spectroscopy together with electron microscopy, X-ray photoelectron spectroscopy, and electrochemical tests indicate that the obtained NiFeOOH/NiFe-LDH after SELF-RECON behave as the real active species that outperform [email protected], with ultralow overpotentials and extraordinary long-term stability.