Engineering MnO ₂ Nanorod-Decorated PP Nonwoven Fabrics with HCHO Degradation, Antibacterial Activity, and Photocatalytic Performance

Formaldehyde (HCHO), a hazardous volatile organic compound (VOC) in indoor environments, urgently requires efficient abatement strategies. MnO2 is renowned for its excellent catalytic activity and enables effective degradation of HCHO at low temperatures. In this study, MnO2 nanorods (NRs) were successfully grown on polypropylene (PP) nonwoven fabric via hydrothermal synthesis, yielding MnO2 NRs @ PP composite material with integrated HCHO removal, antibacterial, and photocatalytic functions. pH value and temperature critically regulated MnO2 morphology. Increasing pH raised the aspect ratio of MnO2 NRs, which transitioned to MnO2 nanoparticles (NPs) when the pH value was above pH 3.5. Higher temperatures promoted MnO2 NRs formation, yet beyond 150 °C, excessive refinement led to MnO2 NRs agglomeration and partial PP fiber melting. Optimal performance was achieved at pH 3.5 and 150 °C, where the composite exhibited a high HCHO removal efficiency of 55.1% along with notable antibacterial and photocatalytic properties. This work provides a feasible synthesis strategy for multifunctional composites that can be applied in indoor air purification and environmental remediation.