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

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

The control of catalytic performance using synthesis conditions is one of the main goals of catalytic research. Two series of Pt-Ti/SBA-15 catalysts with different TiO₂ percentages (n = 1, 5, 10, 30 wt.%) were obtained from tetrabutylorthotitanate (TBOT) and peroxotitanate (PT), as titania precursors and Pt impregnation. The obtained catalysts were characterized using X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), N₂ sorption, Raman, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), hydrogen temperature-programmed reduction (H₂-TPR) and H₂-chemisorption measurements. Raman spectroscopy showed framework titanium species in low TiO₂ loading samples. The anatase phase was evidenced for samples with higher titania loading, obtained from TBOT, and a mixture of rutile and anatase for those synthesized by PT. The rutile phase prevails in rich TiO₂ catalysts obtained from PT. Variable concentrations of Pt⁰ as a result of the stronger interaction of PtO with anatase and the weaker interaction with rutile were depicted using XPS. TiO₂ loading and precursors influenced the concentration of Pt species, while the effect on Pt nanoparticles' size and uniform distribution on support was insignificant. The Pt/PtO ratio and their concentration on the surface were the result of strong metal-support interaction, and this influenced catalytic performance in the complete oxidation of methane at a low temperature. The highest conversion was obtained for sample prepared from PT with 30% TiO₂.

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

A multicomponent composite membrane (P-S-T/C) with three-phase interface heterostructure is ingeniously designed. A polydopamine (PDA)-modified conductive carbon fiber cloth (C_FC) is used as the substrate. Activated poly(vinylidene fluoride) (PVDF) with titanium dioxide (TiO₂) and a silicon dioxide (SiO₂) aerogel are electrospun as the top layer. The three-phase interface heterostructure was formed by TiO₂, conductive C_FC, and the SiO₂ aerogel. Its photocatalytic performance is validated by photodegradation of organic dyes in a low-oxygen (O₂) water environment. On combining with the capillary condensation of a bilayer structure, P-S-T/C exhibits excellent removal capability for anionic and cationic dyes. Moreover, P-S-T/C exhibits excellent stability and recyclability under simulated sunlight. The mechanism study indicates that the separated photogenerated carriers diffuse to the composite membrane surface rapidly on the three-phase interface of P-S-T/C. The abundant O₂ adsorbed on the porous SiO₂ aerogel surface acts as an electron (e^-)-trapping agent, which can also decrease the work function of the composite materials. Superoxide radicals (^•O₂ ^-) play a dominant role in the reaction of photodegradation supported by a free radical-trapping experiment. This work paves a way to design a membrane with photocatalytic performance by constructing the interface heterostructure.

Light-induced synthesis of platinum/titania nanocapsules as an efficient, photosensitive and stable electrocatalyst

Novel Pt/TiO₂ nanocapsules (NCs) having sizes of 40–100 nm and walls of 6–17 nm were successfully synthesized.