Sea urchin-like La-doped MnO₂ for electrocatalytic oxidation degradation of sulfonamide in water

A sea urchin-like La-doped α-MnO₂ catalyst was successfully synthesized by a one-step hydrothermal method. The as-prepared sea urchin-like La-doped α-MnO₂ exhibits electrocatalytic activity for water oxidation. During electrocatalytic water oxidation, the overpotential is 450 mV to reach a catalytic current density of 10 mA/cm² in 1.0 M KOH solution. The urchin morphology and open tunneling structure can fully expose the rich active sites and facilitate mass transfer during electrochemical oxidation process. Moreover, the synthesized material is also applied for sulfonamide (SA) degradation due to the generation of strong oxidizing •OH species during the process of water oxidation. The indirect oxidation of SA by •OH species was proved by radical quenching and capture studies. The catalyst degraded sulfonamide antibiotics with up to 40% efficiency in 2 h. The introduction of the heteroatom La^3⁺ into MnO₂ led to a redistribution of electrons around Mn, which altered the electron density of the metal sites, lowered the average valence state of Mn, facilitated the production of reactive MnIII species, and optimized the exposure density of the active sites. Therefore, the sea urchin-like La-doped MnO₂ material might have application prospects in electrochemical sustainability research.