A series of H2O2 decomposition experiments were performed in the presence of Cu-MSMs without PhACs (Fig. 7) where H2O2 finally decomposed into O2. The decomposition rate had the order of M1 < M2 < M3 < M4, suggesting that GKPIPNPLLGLDST these catalysts exhibited the opposite reactivity for the decomposition of H2O2 compared to the degradation of PhACs, and the rate of H2O2 disappearance increased with increasing the ratio of extraframework copper in Cu-MSMs. M2 exhibited the highest catalytic activity toward the PhACs degradation and lower activity for the H2O2 decomposition, indicating that the framework copper species in Cu-MSMs were extremely selective for promoting Fenton chemistry with minor spurious decomposition of H2O2 to O2. Since oxygen vacancies took part in the decomposition of H2O2 into O2, M4 showed the highest activity for the decomposition of H2O2 due to its higher concentration of oxygen vacancies, which were produced by the extraframework copper species in the form of aggregated copper oxide clusters. In our previous study , no OH formation was determined with the decomposition of H2O2 in aqueous CuOx–H2O2 suspension, confirming this mechanism.