Enhanced water-resistance of Mn-based catalysts for ambient temperature ozone elimination: Roles of N and Pd modification

Cryptomelane-type MnO2 catalysts own excellent ozone (O3) decomposition performance. However, it is urgent to improve their long-term stability at ambient temperature, especially under the presence of water. In the present study, a modification strategy was proposed by N-doping and the successive Pd introduction. The N-doping of MnO2 by NH4Cl (NH4-MnO2) can increase its activity for O3 decomposition. And almost 100% O3 decomposition was achieved within 24 h under water-free atmosphere at ambient temperature (25 °C). Successive Pd addition further promoted the water-resistance of NH4-MnO2 catalyst under high humidity (RH > 90%). In combination with detailed characterizations, it indicated that the enhancements on stability and water-resistance were attributed to synergistic effect among acid sites, oxygen defects and Pd clusters. Finally, the decomposition mechanism of gaseous O3 was proposed based on three decisive active sites above.