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. MnO 2 is renowned for its excellent catalytic activity and enables effective degradation of HCHO at low temperatures. In this study, MnO 2 nanorods (NRs) were successfully grown on polypropylene (PP) nonwoven fabric via hydrothermal synthesis, yielding MnO 2 NRs @ PP composite material with integrated HCHO removal, antibacterial, and photocatalytic functions. pH value and temperature critically regulated MnO 2 morphology. Increasing pH raised the aspect ratio of MnO 2 NRs, which transitioned to MnO 2 nanoparticles (NPs) when the pH value was above pH 3.5. Higher temperatures promoted MnO 2 NRs formation, yet beyond 150 °C, excessive refinement led to MnO 2 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.