Redox-driven synthesis of polyester fiber-supported manganese oxide filters for room-temperature catalytic oxidation of indoor formaldehyde.

Formaldehyde (HCHO) is a common indoor pollutant requiring effective mitigation due to its adverse health effects. This study proposes a redox-driven in-situ growth strategy to directly deposit MnO₂ onto a polyester substrate by exploiting the dual functionality of polyvinyl alcohol (PVA). During synthesis, PVA participates in KMnO4 reduction, promoting Mn3 + formation and oxygen vacancy generation, while residual PVA acts as a binder to enhance adhesion and structural stability. Performance tests showed negligible activity for the polyester filter (F) and PVA-coated filter (PVA/F), whereas MnO₂-grown filters exhibited excellent HCHO oxidation. PVA-MnO₂/F@c5 achieved 97.57% HCHO removal and 94.87% CO2 generation under static conditions, and 98.24% removal within 2 h under dynamic flow. The catalyst filter maintained 90.56% efficiency after five cycles and 87.10% during 24 h operation Characterization (XPS, EPR, H2-TPR, and in-situ DRIFTS) revealed that a high Mn3+/Mn4+ ratio, abundant oxygen vacancies, reactive oxygen species, and enhanced oxygen mobility accelerated intermediate conversion (DOM → HCOO⁻ → CO32- → CO2 + H2O), demonstrating its potential as an effective environmental catalytic system for room-temperature indoor air purification.