Highly efficient replacement of traditional intumescent flame retardants in polypropylene by manganese ions doped melamine phytate nanosheets.

•Mn2+ doped melamine phytate nanosheets are prepared by hydrothermal method.•PAMA-Mn nanosheet has excellent dispersibility and promotes APP dispersion in PP.•PPMn33 with 18 wt% flame retardant achieves UL-94 V-0 and an LOI value of 31.9%.•PPMn33 forms high-quality char layer due to in-situ and targeted catalysis of Mn2+.•The lower fire hazard risk of PPMn33 is clarified by the pyrolysis products.