Synthesis of a rationally designed multi-component photocatalyst pt:Sio<sub>2</sub>:Tio<sub>2</sub> (p25) with improved activity for dye degradation by atomic layer deposition

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Photocatalysts for water purification typically lack efficiency for practical applications. Here we present a multi-component (Pt:SiO2:TiO2 (P25)) material that was designed using knowledge of reaction mechanisms of mono-modified catalysts (SiO2:TiO2, and Pt:TiO2 ) combined with the potential of atomic layer deposition (ALD). The deposition of ultrathin SiO2 layers on TiO2 nanoparticles, applying ALD in a fluidized bed reactor, demonstrated in earlier studies their beneficial effects for the photocatalytic degradation of organic pollutants due to more acidic surface Si–OH groups which benefit the generation of hydroxyl radicals. Furthermore, our investigation on the role of Pt on TiO2 (P25), as an improved photocatalyst, demonstrated that suppression of charge recombination by oxygen adsorbed on the Pt particles, reacting with the separated electrons to superoxide radicals, acts as an important factor for the catalytic improvement. Combining both materials into the resulting Pt:SiO2:TiO2 (P25) nanopowder exceeded the dye degradation performance of both the individual SiO2:TiO2 (P25) (1.5 fold) and Pt:TiO2 (P25) (4-fold) catalysts by 6-fold as compared to TiO2 (P25). This approach thus shows that by understanding the individual materials’ behavior and using ALD as an appropriate deposition technique enabling control on the nano-scale, new materials can be designed and developed, further improving the photocatalytic activity. Our research demonstrates that ALD is an attractive technology to synthesize multicomponent catalysts in a precise and scalable way.