Design of flexible hydrophobic photocatalytic sheets on polydimethylsiloxane substrates based on carrier migration of Si-O-Ti hybrid bonds for photodegradation of dye molecules

[Display omitted] •PBTT composite structures were constructed by dispersing BaTiO3 and TiO2 nanoparticles in PDMS.•Adsorption of PDMS itself and z-like heterojunction formation of BaTiO3/PDMS/TiO2 contributed to the significantly enhanced activity.•PBTT catalysts showed excellent catalytic performance for MB removal with 1.5 times improvement over bare PDMS under visible light.•The formation of Ti-O-Si chemical bond and carrier transfer were verified by FTIR analysis and DFT calculation.•Confirmation of carrier transport mechanism between PDMS with BaTiO3 and TiO2 interfaces by DFT calculations. Rational design of flexible hydrophobic photocatalysts with efficient charge separation transfer channels remains a major challenge for photodegradation of pollutants. A novel PDMS-BaTiO3-TiO2 (PBTT) flexible self-assembled film was constructed by a simple spin-coating method. Continuous dispersion of two semiconductor particles in liquid Polydimethylsiloxane (PDMS) forms a Ti-O-Si chemical bond after sufficient contact. The results show that the Ti-O-Si bond will provide a “channel” for carrier migration between TiO2 and BaTiO3, which not only forms a network structure formed by semiconductor particles, but also provides more surface reaction sites. As a result, the three-hour photodegradation rate of methylene blue (MB) of PBTT was 92.7 %, while the degradation rate of pure PDMS reached 60.7 %. Furthermore, Gaussian 09 W and Materials Studio 2019 (FORCITE and CASTEP modules) were used for the simulation. Density functional theory (DFT) calculations show that carriers are more easily transferred to the PDMS side through the Ti-O-Si bond, which further determines that carriers can be shifted in the PBTT directionally. In addition, the material also has the ability of hydrophobicity and pollutant adsorption. This study will be expected to open up new avenues for the application of flexible multiheterojunction structured photocatalysts for pollutant treatment.