Transparent ZnO-coated polydimethylsiloxane-based material for photocatalytic purification applications

We describe production and photocatalytic properties of a material based on polydimethylsiloxane (PDMS) as a carrier substrate coated with microparticles of zinc oxide (ZnO). The ZnO microparticles are fabricated by our original hydrothermal method and intentionally have a defect structure. According to our understanding, this peculiar defect structure contributes to the greatly enhanced photocatalytic properties of the ZnO material. The resulting photocatalyst demonstrates high activity under visible light (410 nm) in the process of phenol degradation in water solution, while generally ZnO is inactive below the UV range. In addition, we compare the photocatalytic activity of our ZnO/PDMS composite to that of the same ZnO powder suspension in a similar setup. We find that the same activity is achieved by three orders of magnitude smaller amount of ZnO in our composite compared to the powder suspension. The ZnO/PDMS interface exhibits sufficiently strong bonding for stable operation that is ensured during material production. The obtained photocatalytic material preserves the transparency of PDMS due to the low amount of attached ZnO (about 0.1% by mass). The transparency of the photocatalytic ZnO/PDMS material enables easy performance upgrades by constructing multilayer or manifold fluid treatment devices.