Ru/CdS quantum dots templated on clay nanotubes as visible light active photocatalysts: optimization of S/Cd ratio and Ru content.

Nanoarchitectual approach based on in situ quantum dots formation within/outside clay nanotubes was developed. The efficient and stable photocatalysts active under visible light were achieved with ruthenium doped cadmium sulfide quantum dots templated on the surface of azine modified halloysite nanotubes. The catalytic activity was tested in hydrogen evolution reaction from water solution of electrolytes under visible light. Ru doping enhanced the photocatalytic activity of CdS quantum dots thanks to better light adsorption and electron-hole pair separation due to formation of metal-semiconductor heterojunction. We found that sulfur to cadmium ratio (S/Cd) was the major factor for stable nanoparticles formation on the surface of the azine modified clay. The quantum yield of 9.3% was reached using Ru/CdS/Halloysite containing 5.2 wt. % of Cd doped with 0.1 wt. % of Ru and S/Cd ratio equaling one. CdS/Halloysite hybrid in vivo and in vitro studies demonstrated an absence of toxic effect in eukaryotic cells and nematodes in short term tests, thus providing promising photosensitive materials for multiple applications.