Voltage-induced rapid and deep reconstruction of rationally designed MnCr-LDH: a pathway to efficient water oxidation

Reconstruction-derived oxyhydroxides possessing high-valent metal centers have been extensively investigated in recent years for their potential to enhance oxygen evolution reaction (OER) activity. However, the reconstruction processes and underlying reaction mechanisms of layered double hydroxides (LDHs) remain insufficiently explored. Investigating catalyst reconstruction and reaction pathways presents significant challenges. The Mn x Cr y LDH catalysts demonstrate enhanced OER performance after 20 cycles of cyclic voltammetry (CV) activation. Among them, the Mn 3 Cr 2 LDH 20th sample exhibits particularly low overpotentials of only 354.0 mV at room temperature and 272.4 mV at an industrial-relevant temperature (65 °C) to achieve a current density of 100 mA cm −2 . Furthermore, the catalyst maintains outstanding performance in alkaline natural seawater. CV cycling triggers rapid structural reorganization, leading to the formation of highly OER active β-MnOOH and simultaneously promoting Cr leaching. This Cr leaching generates abundant defect sites, which not only expose additional electroactive centers but also significantly increase the electrochemically active surface area (ECSA). Experimental evidence strongly suggests that the derived β-MnOOH phase boosts OER activity mainly via the lattice oxygen mechanism (LOM). This work highlights the robust potential of manganese-based OER catalysts for direct seawater electrolysis.