Preparation, characterization, and application of TiO₂-patterned polyimide film as a photocatalyst for oxidation of organic contaminants

Photocatalytically active TiO₂-patterned polyimide (PI) films (PI-TiO₂) were fabricated using thermal transfer patterning (TTP). When subjected to hot pressing, the TiO₂ nanoparticles electrosprayed on steel mesh templates were successfully transferred and formed checker plate patterns on PI film. FE-SEM studies confirmed that pressing at 350 °C and 100 MPa was optimum for obtaining patterns with uniform TiO₂ coverage. When the quantity of TiO₂ on the template increased, the amount of it immobilized on PI film also increased from 0.3245 to 1.2378 mg per 25 cm². XPS studies confirmed the presence TiO₂ on the patterns, and indicated the formation of carboxylic acid and amide groups on the PI surface during TTP. When tested under UVA irradiation, PI-TiO₂ with 1.2378 mg/25 cm² TiO₂ loading exhibited the highest photocatalytic performance for methylene blue (10 μM) degradation, with a rate constant of 0.0225 min⁻¹ and stable photocatalytic efficacy for 25 cycles of reuse. The PI-TiO₂ was also successfully used to degrade amoxicillin, atrazine, and 4-chlorophenol. During photocatalysis, the toxicity of 4-chlorophenol against Vibrio fischeri and the antibiotic activity of amoxicillin against Escherichia coli were decreased. Overall, TTP was found to be a potentially scalable method for fabricating robust immobilized TiO₂ photocatalyst.