Nanocomposites based on Cu2O and Ca‐montmorillonite (Ca+‐MMT) with different composition were successfully prepared via a simple hydrothermal method. The as‐prepared Cu2O‐MMT nanocomposites can rapidly catalytically oxidize the colorless chromogenic substrate, 3,3′,5,5′‐tetramethylbenzydine (TMB) into blue oxTMB with the aid of the H2O2 only in 30 s, which were observed by the naked eye. The reaction catalyzed by the Cu2O‐MMT nanocomposites followed the Michaelis–Menten kinetics. Compared to the MMT or Cu2O alone, Cu2O‐MMT with different mass ratio exhibited an enhanced peroxidase‐like activity. The fabricated H2O2 sensor exhibited a good response to H2O2 with a linear detection range from 3 to 80 μM as well as a detection limit of 2.395 μM. Taking the advantages of the Cu2O‐MMT nanocomposites, including outstanding peroxidase‐like activity and high sensitivity for colorimetric detection of H2O2, a colorimetric sensor based on the Cu2O‐MMT nanocomposites was designed and used to rapidly detect H2O2 in a short time.

The key factor in the synthesis of intrinsic flame retardant polymers is the thermal stability and reactivity of phosphorus-based flame retardants.