(82d) Fabricating Multicomponent Photocatalysts Using Atomic Layer Deposition

This contribution focuses on the surface modification of TiO₂(P25), improving the performance of it. Atomic layer deposition (ALD) allows us to precisely control the deposition of many different materials at the atomic level, which could improve photocatalyst design and optimize activity.

One way to boost the activity of TiO₂(P25) particles is to deposit a small amount of platinum or gold on them. We show the effect of depositing small amounts (<1wt%) Pt or Au on TiO₂ using ALD in a fluidized bed reactor. A disadvantage of using these noble metals are the high costs involved. The deposition of Cu₂O on TiO₂(P25) is a cheaper alternative to noble metals such as Pt to improve the photocatalytic activity. We were able to deposit Cu₂O nanoclusters on the surface of TiO₂ (P25) particles using ALD in a fluidized bed. Very low loaded Cu₂O:TiO₂(P25) (0.4wt% Cu) demonstrated a double photocatalytic activity for the degradation of several dye molecules compared to bare P25. An even cheaper and more stable material is SiO₂. By precisely controlling the thickness of the SiO₂ coating we were able to tune the photocatalytic activity from enhancement (<1.2 nm) to suppression (>1.2 nm) with an optimum activity at a coating thickness of about 0.7 nm.

Using the insights gained, we developed a new catalyst material by building up a material with a thin layer of SiO₂ on TiO₂(P25), followed by the deposition of Pt clusters to combine both components’ advantages. Pt:SiO₂:P25 exhibited a further improvement in the activity for the degradation of Acid Blue 9 (6x better than P25), where the optimal loading ranges of SiO₂ and Pt on P25 in the combined material are similar to the mono-modified materials SiO₂:P25 and Pt:P25. This demonstrates that the combination of multiple materials opens the door to further catalyst improvement using ALD.