Fast-response Phosphorescence Sensor for Dissolved Oxygen Detection Based on PtOEP/TiO₂/CB@PFFE Sensing Film

A fast-response phosphorescence sensor for dissolved oxygen (DO) detection based on PtOEP/TiO₂/CB@PFFE sensing film was developed. The DO sensing film features a tri-layer structure, comprising a sensing layer, a light-scattering layer, and a light-blocking layer. Fluorinated polymer PFFE as matrix was synthesized via free radical polymerization using 4-trifluoromethyl styrene (TFMST), 2,2,2-trifluoroethyl methacrylate (TFEMA) and 2-ethylhexyl acrylate (2-EHA) as monomers and 2,2-azobis(isobutyronitrile) (AIBN) as initiator. The sensing layer, light-scattering layer and light-blocking layer were fabricated by embedding platinum octaethylporphyrin (PtOEP), TiO₂ and carbon black (CB) in PFFE, respectively. The addition of light-scattering layer and light-blocking layer enhances the phosphorescence intensity and phosphorescence lifetime of the PtOEP/TiO₂/CB@PFFE sensing film, further improving the detection sensitivity of the sensor. The PtOEP/TiO₂/CB@PFFE sensor demonstrated a response time of 30 s and a recovery time of 150 s and exhibited excellent reproducibility, reversibility and stability. The Stern-Volmer constant (K_SV) of the Stern-Volmer curve was 0.4584 L/mg and the correlation coefficient (R) of the curve reached as high as 0.9993, indicating that the PtOEP/TiO₂/CB@PFFE sensor exhibited high sensitivity for DO detection.