Synthesis of a Rationally Designed Multi-Component Photocatalyst Pt:SiO2:TiO2(P25) with Improved Activity for Dye Degradation by Atomic Layer Deposition

Abstract

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.

Multicomponent Composite Membrane with Three-Phase Interface Heterostructure as Photocatalyst for Organic Dye Removal

“…The characteristic peaks at 529.3 and 531.4 eV for P-TiO 2 /C were attributed to the TiO 2 lattice oxygen and surface hydroxyl groups, respectively. In comparison to P-TiO 2 /C, the enhanced and broadened peak of P-S-T/C at 531.4 eV was due to the increased contents of hydroxyl groups on the material’s surface upon the addition of the SiO 2 aerogel …”

“…By combining with free radical-trapping experiments, we proposed a reasonable hypothesis that the addition of the SiO 2 aerogel would increase the O 2 contents of the composite membrane, which would bond with the separated e – to generate • O 2 – via photocatalysis. 68 , 69 To compare the contents of • O 2 – formed by P-TiO 2 /C and P-S-T/C in the process of photodegradation, EPR experiment was conducted in methanol using DMPO as a capture agent. As shown in Figure 11 b, the DMPO– • O 2 – signal intensity of P-S-T/C was higher than that of P-TiO 2 /C.…”

“…In comparison to P-TiO 2 /C, the enhanced and broadened peak of P-S-T/C at 531.4 eV was due to the increased contents of hydroxyl groups on the material's surface upon the addition of the SiO 2 aerogel. 68 2.4.4. Possible Mechanism of Organic Dye Removal.…”

Variation in Metal–Support Interaction with TiO2 Loading and Synthesis Conditions for Pt-Ti/SBA-15 Active Catalysts in Methane Combustion

“…The immobilization of metal oxides and metal nanoparticles onto SBA-15 silica favors their dispersion [ 27 , 28 ]. Thus, a stronger metal–support interaction (SMSI) was evidenced for Pt/xTiO 2 -SBA-15 nanocomposites than for classical Pt/TiO 2 P25 catalysts [ 29 , 30 ]. The use of mesoporous silica-ordered channels as hosts for titanium species is a way to control and stabilize small-size particles and thus adjust interaction with Pt through the selection of the synthesis method, composition, and precursors.…”