New Route for the Preparation of Pd and PdAu Nanoparticles Using Photoexcited Ti-Containing Zeolite as an Efficient Support Material and Investigation of Their Catalytic Properties

Abstract

A simple and unique route to synthesize nanosize Pd particles using a zeolite support including a single-site Ti oxide moiety (TS-1) under UV-light irradiation has been developed. By the photoassisted deposition (PAD) method, a Pd precursor can be deposited directly on the photoexcited tetrahedrally coordinated Ti oxide moiety within the zeolite frameworks from an aqueous solution of Pd. The subsequent reduction with H2 generates the nanosized Pd metal particles with a narrow size distribution (PAD-Pd/TS-1). Characterization by XAFS and TEM analysis revealed that the size of the metal particles depends on the preparation methods and that the smaller sizes of Pd nanoparticles were formed on the photodeposited catalysts compared with the conventionally prepared impregnated catalysts. PAD also provides PdAu bimetallic nanoparticles from an aqueous solution of mixture of PdCl2 and HAuCl4. The catalytic activities in the direct synthesis of hydrogen peroxide (H2O2) using H2 and O2 gases under atmospheric pressure were strongly dependent on the preparation method and the presence of Au atoms. Here, both deposition of PdAu onto the TS-1 moiety under UV-light irradiation was the most efficient for the above reaction. The applicability of the present catalytic system is highlighted by the one-pot reaction of phenol using PAD-Pd/TS-1 in the presence of H2 and O2, in which both Pd nanoparticles and isolated Ti oxide moieties within the frameworks participate in the formation of H2O2 and oxidation of phenol, respectively.

Fabrication of Gold/Titania Photocatalyst for CO2 Reduction Based on Pyrolytic Conversion of the Metal–Organic Framework NH2-MIL-125(Ti) Loaded with Gold Nanoparticles

“…45-47 One of the most studied composites is Au/TiO2 material, which can be obtained by deposition-precipitation, colloidal synthesis or photodeposition of Au. [48][49][50][51][52] Recently, the reduction of CO2 to formate has been studied using Au and Pt loaded MOFs. 53 Herein, the goal of this study is to combine the GNPmodification of TiO2 with the possible advantages of using a Tibased MOF as sacrificial precursor for the TiO2 component while also acting as support matrix for the dispersion and stabilization of small GNPs.…”

Synthesis of Ce ions doped metal–organic framework for promoting catalytic H2 production from ammonia borane under visible light irradiation

“…Subsequently, Pt@MOFs assemblies, prepared by photocatalytic deposition of Pt nanoparticles into the cavities of two phosphorescent UiO MOFs built from two Ir-phosphor-derived dicarboxylated ligands, were found to be effective photocatalysts for hydrogen generation. 23 In contrast, the nodes of MOFs possess the unique atomic coordination, 24,25 which holds a great potential for promoting unusual redox chemical reaction. On the other hand, the single site porous materials, in which foreigner metal ions were introduced in the skeleton of porous materials as a mediator have been applied for many photocatalytic application.…”

Preparation of Cr–Ti Binary Oxide Anchored Mesoporous Silica by CVD Method and Their Photocatalytic Activities

“…-oxide containing catalyst have also attracted much attention due to their visible light sensitivity and fascinating catalytic activities [9][10][11][12]. Our group has also demonstrated that transition metal oxides containing silica-based materials, which were called single-site photocatalyts, can be used not only to promote the photocatalytic reactions but also to form nanosized metals and alloys [1,13,14]. The preparation of binary oxide containing mesoporous silica was also successfully attained by photo-assisted deposition (PAD) technique, which shows the high selectivity in the partial oxidation of propylene into propylene oxide [13,15].…”