Visible light-driven MXene/Sr-TiO₂-modified PVDF membranes for autonomous self-cleaning and high-efficiency dye removal

Membrane fouling and limited permeability restrict the expansion of membranes, in wastewater purification. We developed PVDF membranes by integrating hierarchically structured MXene/strontium-doped titanate nanotubes (MX/Sr-TiNT) through non-solvent-induced phase separation. Thorough compositional tuning (0.25–1.0 and detailed analysis revealed structure-function correlations driving membrane efficacy. The optimized composite (0.75 MX/Sr-TiNT) demonstrated outstanding hydrophilicity (49° contact angle) and achieved an impressive fivefold increase in pure water flux (803 ± 13 L·m^−2·h⁻¹ compared to 155 ± 8 L·m⁻²·h⁻¹ for pristine PVDF) accompanied by an 80 % decrease in membrane resistance. Multi-dye separation reached complete methylene blue rejection (82 %) along with continuous photocatalytic regeneration, under ambient visible light. The combined two-dimensional MXene and one-dimensional Sr-TiNT heterojunction facilitated effective charge carrier separation via oxygen vacancy-driven pathways. Fouling resistance decreased by 88–98 % while diffuse reflectance spectroscopy verified a 60 % photodegradation of surface-adhered MB, leading to flux restoration (100 % FRR) following irradiation. This unified mechanism, linking adsorption and photocatalytic radical production, made the membrane autonomous and self-cleaning over several cycles. This work establishes a sustainable platform for next-generation photocatalytic membranes that simultaneously maximize permeability, selectivity, and antifouling properties while eliminating chemical regeneration requirements.