Selective Electrosynthesis of High‐Concentration Mn ^IV ═O in Oxidant‐Free Systems for Sustainable Water Remediation

Abstract

ABSTRACT High‐valent metal‐oxo (HVMO) exhibit selective oxidation properties, but their selective synthesis and high‐concentration aggregation remain challenging in oxidant‐free systems. This work employs sinusoidal alternating current (AC) to efficiently synthesize Mn IV ═O with water as an oxygen source. The positive half‐cycle continuously transforms H 2 O adsorbed on ≡Mn II site into high‐concentration HVMO through a multi‐step electron transfer and deprotonation process (≡Mn II −OH 2 →≡Mn II −OH→≡Mn III −OH→≡Mn IV ═O). The negative half‐cycle reduces the inactive Mn III generated during the consumption of Mn IV ═O back to the initial Mn II state and simultaneously alleviates proton accumulation. This AC strategy achieves stable cycling of the Mn oxidation state and effectively suppresses the overoxidation of ≡Mn III −OH to ≡Mn IV −OOH, thereby realizing the efficient preparation of HVMO with 99.3% selectivity and a steady‐state concentration of 2.8 × 10 −6  mM. Employing the selective removal of bisphenol A (BPA) as a model, Mn IV ═O can selectively oxidize target pollutants in the presence of interferents, achieving removal rates approaching 99% within 1 h. Stable operation in a continuous flow reactor scaled up by 40 times for over 100 h highlights the application potential of this strategy. This work reveals a novel green strategy to generate HVMO without rectification or additional oxidants for water purification.