Water-Driven\nSurface\nLattice Oxygen Activation in\nMnO<sub>2</sub> for Promoted Low-Temperature NH<sub>3</sub>–SCR

Water\nis ubiquitous in various heterogeneous catalytic\nreactions,\nwhere it can be easily adsorbed, chemically dissociated, and diffused\non catalyst surfaces, inevitably influencing the catalytic process.\nHowever, the specific role of water in these reactions remains unclear.\nIn this study, we innovatively propose that H<sub>2</sub>O-driven\nsurface lattice oxygen activation in γ-MnO<sub>2</sub> significantly\nenhances low-temperature NH<sub>3</sub>–SCR. The proton from\nwater dissociation activates the surface lattice oxygen in γ-MnO<sub>2</sub>, giving rise to a doubling of catalytic activity (achieving\n90% NO conversion at 100 °C) and remarkable stability. Comprehensive <i>in situ</i> characterizations and calculations reveal that spontaneous\nproton diffusion to the surface lattice oxygen reduces the orbital\noverlap between the protonated oxygen atom and its neighboring Mn\natom. Consequently, the Mn–O bond is weakened and the surface\nlattice oxygen is effectively activated to provide excess oxygen vacancies\navailable for converting O<sub>2</sub> into O<sub>2</sub><sup>–</sup>. Therefore, the redox property of Mn–H is improved, leading\nto enhanced NH<sub>3</sub> oxidation-dehydrogenation and NO oxidation\nprocesses, which are crucial for low-temperature NH<sub>3</sub>–SCR.\nThis work provides a deeper understanding and fresh perspectives on\nthe water promotion mechanism in low-temperature NO<sub><i>x</i></sub> elimination.