Co-doped cryptomelane-type manganese oxide in situ grown on a nickel foam substrate for high humidity ozone...

Monolithic catalysts with excellent O₃ catalytic decomposition performance were prepared by in situ loading of Co-doped KMn₈O₁₆ on the surface of nickel foam. The triple-layer structure with Co-doped KMn₈O₁₆/Ni₆MnO₈/Ni foam was grown spontaneously on the surface of nickel foam by tuning the molar ratio of KMnO₄ to Co(NO₃)₂·6H₂O precursors. Importantly, the formed Ni₆MnO₈ structure between KMn₈O₁₆ and nickel foam during in situ synthesis process effectively protected nickel foam from further etching, which significantly enhanced the reaction stability of catalyst. The optimum amount of Co doping in KMn₈O₁₆ was available when the molar ratio of Mn to Co species in the precursor solution was 2:1. And the Mn2Co1 catalyst had abundant oxygen vacancies and excellent hydrophobicity, thus creating outstanding O₃ decomposition activity. The O₃ conversion under dry conditions and relative humidity of 65%, 90% over a period of 5 hr was 100%, 94% and 80% with the space velocity of 28,000 hr^-1, respectively. The in situ constructed Co-doped KMn₈O₁₆/Ni foam catalyst showed the advantages of low price and gradual applicability of the preparation process, which provided an opportunity for the design of monolithic catalyst for O₃ catalytic decomposition.