Construction and performance optimization of PVDF deoxygenation membranes via Bi/C–TiO2 photocatalytic synergy

Metal corrosion induced by dissolved oxygen necessitates cost-effective and efficient deoxygenation technologies. Membrane-based deoxygenation has become the mainstream approach owing to its simplicity, low energy consumption, and environmental compatibility; however, relatively low deoxygenation efficiency remains a critical challenge that limits its broader application. Polyvinylidene fluoride (PVDF), with its excellent chemical resistance, anti-aging stability, and good processability, is an ideal material for fabricating deoxygenation membranes. In this study, bismuth/carbon (Bi/C) co-doped titanium dioxide (TiO2) nanoparticles were incorporated into a PVDF matrix to synergistically enhance both the mechanical properties and the deoxygenation efficiency through pore structure regulation and the photocatalytic activity of TiO2. The influence of PVDF concentration on membrane formation was first examined, and the optimal film-forming property and mechanical performance were obtained at 15 wt. %. Based on this, Bi and C were doped into TiO2 at 2% of the TiO2 mass and subsequently calcined to yield modified TiO2, which was then blended with PVDF to prepare composite membranes. At a fixed PVDF concentration of 15 wt. %, when the addition of modified TiO2 reached 7.5 wt. %, the deoxygenation efficiency reached 35.02% under xenon lamp irradiation, whereas it dropped to 14.45% under complete darkness, confirming that the photocatalytic activity of Bi/C–TiO2 is the dominant factor driving the enhanced performance. The porosity was maintained at 73% and the water contact angle remained in the range of 90°–105°, indicating persistent hydrophobicity. Scanning electron microscopy and elemental mapping analyses confirmed that the modified TiO2 particles were uniformly dispersed within the membrane. This strategy that integrates doping modification with photocatalytic synergy offers a new avenue for the development of high-performance PVDF-based deoxygenation membranes.