Enhanced hydrogen production under a visible light source and dye degradation under natural sunlight using nanostructured doped zinc orthotitanates

The nanostructured Ag and Co doped zinc orthotitanates (ZOT) were synthesized using a combustion method. The structural and optical analysis shows the existence of cubic and tetragonal phases. Morphological study by FESEM reveals the formation of a web like structure along with pot holes by the self-assembly of spherical nanoparticles of ∼50 nm size. Further, TEM investigations reveal diffused and uneven shaped nanoparticles in the range of 10-25 nm. BET surface area measurements show a decrease in surface area due to doping. These ZOTs were employed for photocatalytic dye degradation (Acid Orange-8 and Rhodamine-B) under natural sunlight. The prima facie observations showed Ag@Zn₂TiO₄ to be an excellent photocatalyst for dye degradation. The kinetics study shows the order of the reaction to be in the range of 1.1-1.41. The ZOTs synthesized have also been used for photocatalytic hydrogen production from H₂S under visible light irradiation. It is noteworthy that utmost H₂ production (2784 μmol h^-1/100 mg) was observed for Ag@Zn₂TiO₄ which is much higher than that achieved with visible light active photocatalysts reported so far. The dye degradation and hydrogen production from H₂S using ZOT are hitherto unattempted. The nanostructured Zn₂TiO₄ will be a potential visible light active photocatalyst for waste degradation and water splitting.