Dual-site doping enhances the performance of NiMnFe-LDH catalysts for alkaline oxygen evolution

Nickel-iron layered double hydroxides (NiFe-LDHs) are among the most promising non-precious metal catalysts for alkaline oxygen evolution reaction (OER), yet their performance still requires further improvement for practical applications. While introducing a third metal is a common strategy, most dopants occupy only a single valence site, limiting their ability to simultaneously optimize both Ni 2 + and Fe 3+ centers in the LDH lattice. This work exploits the unique dual-valent character of manganese (Mn 2+ /Mn 3+ ) to achieve simultaneous substitution at both Ni 2+ and Fe 3+ sites, a novel approach confirmed by XPS analysis. The resulting NiMnFe-LDHs catalyst exhibits exceptional OER activity (278 mV @10 mA·cm −2 ) and 200-hour stability at industrial current densities (400 mA·cm −2 ). In -situ Raman spectroscopy reveals that Mn doping facilitates the LDH-to-NiFeOOH transformation during OER, while XPS demonstrate the Mn 2+ /Mn 3+ -induced electron redistribution enhances both charge transfer and intermediate adsorption. This valence-mediated dual-site doping strategy establishes a new paradigm for designing high-performance LDH catalysts.