Electrospinning Machine| Binder-Freelmmobilization ofPhotocatalyst on Membrane Surface forEfficient PhotocatalyticH20,ProductionandWater Decontamination

Research Background
Photocatalysis, as a green and clean catalytic technology, holds great potential in environmental remediation, chemical synthesis, and renewable energy. In recent years, the light utilization efficiency and catalytic performance of photocatalytic materials have significantly improved, but practical applications of existing photocatalytic systems still face challenges. Widely used suspended particle photocatalysts suffer from issues like easy sedimentation and loss, while immobilized photocatalysts (via binder crosslinking or direct mixing with substrate materials) exhibit problems such as limited catalytic site exposure and low light utilization efficiency, leading to reduced overall photocatalytic activity.

Content Summary
To address these challenges, Professor Li Wenwei's team at the University of Science and Technology of China proposed a novel binder-free surface self-immobilization strategy for constructing photocatalytic membranes. The team used the organic solvent N,N-dimethylformamide (DMF) to soak polyvinylidene fluoride (PVDF) support membranes, softening and expanding the membrane fibers. This process enlarged the micropores formed by the fibers, enabling the capture of particle catalysts. Subsequently, as DMF evaporated, the fibers contracted, reducing pore size and firmly trapping the photocatalyst particles on the membrane surface. The findings were published in *Nano-Micro Letters (IF 31.6)* under the title "Binder-Free Immobilization of Photocatalyst on Membrane Surface for Efficient Photocatalytic H₂O₂ Production and Water Decontamination."

Results demonstrated that the photocatalytic activity of SSPM was approximately 4.6 times higher than that of traditional embedded photocatalytic membranes (MEPM), with excellent long-term operational stability. The SSPM-based UV/H₂O₂ process enabled efficient purification of various water bodies, showing significant practical potential.

Highlights

1. Innovation: A binder-free surface self-immobilization strategy was developed to prepare highly active photocatalytic membranes. DMF-treated PVDF membranes underwent "expansion-contraction" during solvent evaporation, efficiently capturing and binding catalyst particles (e.g., CoOx/Mo:BiVO₄/Pd) while maintaining high exposure.

2. Enhanced Activity & Stability: SSPM exhibited 4.6-fold higher H₂O₂ production activity than MEPM and superior stability during continuous operation.

3. Broad Applications: The SSPM-based process enabled efficient H₂O₂ synthesis and in-situ use for rapid removal of organic micropollutants, advancing photocatalytic water treatment technologies.

Graphical Abstract

1. Preparation & Characterization of SSPM:

   • Figure 1a illustrates the SSPM fabrication: DMF-treated PVDF fibers underwent softening-expansion-contraction, trapping catalyst particles on the surface. SEM/EDS (Fig. 1b–1c) confirmed surface-localized catalysts, unlike MEPM’s internal dispersion. High-magnification SEM (Fig. 1d) showed PVDF fibers wrapping catalyst particles. Unstable catalyst adhesion in SUPM (without DMF treatment) led to significant loss under flow (Fig. S6).

Fig. 1: (a) SSPM fabrication; (b–d) SEM/mapping of SSPM; (e–g) MEPM morphology.

2.H₂O₂ Production Performance:

• SSPM’s high catalyst exposure yielded 4.6× higher H₂O₂ activity than MEPM (Fig. 2a) and maintained stability over 20 cycles (Fig. 2b), while SUPM lost 54.7% activity after 10 cycles.

Fig. 2: (a) H₂O₂ activity; (b) cycling stability; (c) mass transfer/catalyst fixation; (d) benchmark comparison; (e) continuous-flow H₂O₂ yield.

3.Reactant Accessibility & H₂O₂ Diffusion:

• Multi-physics simulations revealed oxygen diffusion limitations in MEPM (Fig. 3a). SSPM’s hydrophobic surface facilitated H₂O₂ desorption, minimizing decomposition (Fig. 3b–3c).

Fig. 3: (a) Oxygen distribution in MEPM/SSPM; (b) H₂O₂ decomposition rates; (c) cumulative yields; (d) H₂O₂ generation/diffusion.

4.UV/H₂O₂ Process for Pollutant Degradation:

• SSPM achieved complete removal of 10 mg/L tetracycline (TC) and bisphenol A (BPA) within 1 hour (Fig. 4a), with 10× faster degradation than UV alone. It maintained efficiency in real water matrices (lake, tap, and wastewater; Fig. 4b) and continuous-flow stability (Fig. 4d).

Fig. 4: (a) Pollutant removal; (b) real-water efficiency; (c) experimental setup; (d) continuous-flow performance.

Conclusion
This study presents a binder-free surface self-immobilization strategy to overcome performance decay in traditional catalyst fixation methods. The SSPM-enabled UV/H₂O₂ process achieved efficient pollutant removal, advancing practical photocatalytic water treatment and inspiring catalytic membrane design.

Original Link: https://doi.org/10.1007/s40820-025-01822-0