Fabrication of PVDF/TiO2@CQDs photocatalytic films by ink-jet printing for dye degradation under visible light

PVDF/TiO2@CQDs hybrid photocatalytic thin films were prepared by ink-jet printing. The printing ink was prepared with the TiO2, TiO2(s)@CQDs (surface composite), and TiO2(i)@CQDs (situ doping) nanoparticles as precursors, respectively. Compared to TiO2(s)@CQDs, TiO2(i)@CQDs has a smaller particle size (about 10.01 nm) and a narrower particle size distribution (6∼14 nm), which can improve the photocatalytic effect while avoiding nozzle clogging. The PVDF/TiO2(i)@CQDs hybrid film exhibited a high degradation efficiency (η) of 93.71 % for Rhodamine B (RhB) within 150 min under visible light with a catalyst load of only 0.49 wt%. The reaction rate constant (ks) of the PVDF/TiO2(i)@CQDs film was about 4.3 times higher than that of the PVDF/TiO2(s)@CQDs film. The small particle size of this S-scheme TiO2(i)@CQDs heterostructure nanoparticle and the more effective contact interface formed between TiO2 and carbon quantum dots (CQDs) further facilitated electron transfer and enhanced photoactivity. The firmly immobilized catalysts on the Polyvinylidene fluoride (PVDF) film substrate through Ti-F coordination bonds ensured the reusability and stability of the photocatalytic film (the η of RhB still reached 88.05 % after 10 consecutive cycles). This work provides a new strategy for the application of ink-jet printing technology in photocatalysis.