3D-Printed Metal–Organic Framework/Polymer Catalytic Filters for Detoxification of Nerve Agent Simulants

The growing threat of chemical warfare agents (CWAs) highlights the urgent need for advanced personal protective equipment to protect military personnel, first responders, and civilians from inhalation exposure. Conventional breathable mask filters primarily rely on adsorption to trap CWAs, which can lead to secondary contamination due to desorption. Therefore, there is a critical need for filter materials that not only allow airflow but also actively detoxify CWAs. In this study, we developed 3D-printed catalytic filters using a composite of Ultem and polymer of intrinsic microporosity (PIM-1) in a 40/60% v/v ratio, integrated with 30 wt% Ce(OH)₄. This base material (PU@Ce(OH)₄) was further functionalized with MOF-808-NH₂ to enhance the catalytic activity. Two incorporation strategies were employed: (1) paste incorporation (MOF-I_PU@Ce(OH)₄), where 6.2 wt% MOF-808-NH₂ was mixed directly into the printing paste prior to fabrication; and (2) post-print coating (MOF-C_PU@Ce(OH)₄), where the printed PU@Ce(OH)₄ structure was coated with MOF-808-NH₂ via a supramolecular assembly method. The filters (PU@Ce(OH)₄, MOF-I_PU@Ce(OH)₄, and MOF-C_PU@Ce(OH)₄) were evaluated for permeability and catalytic degradation of the nerve agent simulant dimethyl 4-nitrophenyl phosphate (DMNP). Among them, MOF-C_PU@Ce(OH)₄ exhibited the best balance of breathability and catalytic efficiency, attributed to the increased accessible surface area provided by the coating method. MOF-C_PU@Ce(OH)₄ achieved complete DMNP hydrolysis within 20 min, with a half-life (τ₁/₂) of 6.08 min. In comparison, the paste-incorporated filter (MOF-I_PU@Ce(OH)₄) required 30 min for complete degradation, with a τ₁/₂ of 14.8 min. These findings demonstrate the superiority of MOF coating in development of breathable filters that combine adsorption and catalytic functionalities for capture and in-situ destruction of CWAs and their simulants.