Ozone Decomposition Mechanism at Different Structural Oxygen Vacancies on Manganese Dioxide

MnO 2 is a promising catalyst for ozone decomposition, and oxygen vacancy has been regarded as the determinant factor for decomposition effectiveness. MnO 2 with two different oxygen vacancies, that is, [Mn 3+ ]-V 0 -[Mn 3+ ] and [Mn 3+ ]-V 0, was synthesized and characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The catalytic decomposition rate of [Mn 3+ ]-V 0 -[Mn 3+ ] was significantly greater than that of [Mn 3+ ]-V 0 . MnO 2 with [Mn 3+ ]-V 0 -[Mn 3+ ] showed the lowest average oxidation state of Mn and the fastest electron transfer capacity. A new pathway for ozone decomposition at [Mn 3+ ]-V 0 -[Mn 3+ ] was proposed accordingly. The reaction sequence involved (i) dissociative adsorption of ozone to form an oxygen molecule and an atomic O – at [Mn 3+ ], (ii) reaction of O – further with another O 3 molecule to form [Mn 4+ ]-O-O-[Mn 4+ ], and (iii) [Mn 4+ ]-O-O-[Mn 4+ ] decomposition to form a gas-phase oxygen molecule and [Mn 3+ ]-V 0 -[Mn 3+ ] for further ozone adsorption. This work revealed a new avenue for designing efficient catalysts for ozone elimination.