Morphology and CO Oxidation Activity of Pd Nanoparticles on SrTiO₃ Nanopolyhedra

Abstract

Single crystal SrTiO3 nanocuboids having primarily TiO2-(001) surfaces and nanododecahedra having primarily (110) surfaces were created by two separate hydrothermal synthesis processes. Pd nanoparticles grown on the two sets of STO nanopolyhedra by atomic layer deposition show different morphologies and CO oxidation performance. Transmission electron microscopy and small-angle X-ray scattering show that 2–3 nm Pd nanoparticles with 3–5 nm interparticle distances decorate the STO surfaces. When the number of ALD cycles increases, the growth of the Pd nanoparticles is more significant in size on TiO2-(001)-STO surfaces, while that on (110)-STO surfaces is more predominant in number. High resolution electron microscopy images show that single crystal and multiply twinned Pd nanoparticles coexist on both types of the STO nanopolyhedra and exhibit different degrees of adhesion. The CO oxidation reaction, which was employed to determine the dependence of catalytic activity, showed that the Pd catalytic performance was dominated by the coverage of CO, which is more directly related to Pd nanoparticle size than to shape. CO turnover frequency analysis and diffuse reflectance infrared Fourier transform spectroscopy show that regardless of the shape or degrees of wetting, larger Pd nanoparticles (∼3 nm) have lower catalytic activity due to high CO coverage on nanoparticle facets. Smaller nanoparticles (∼2 nm) have more edge and corner sites and exhibit 2–3 times higher TOF at 80 and 100 °C.

Understanding the Impact of Defects on Catalytic CO Oxidation of LaFeO3-Supported Rh, Pd, and Pt Single-Atom Catalysts

“…1−6 The cost of PGMs and their low-temperature performance as well as their aggregation into larger particles when operated at elevated temperatures pose significant challenges in developing better catalysts. 7,8 These aspects explain why already for a long time substantial efforts have been made to reduce the content of precious metals in these catalysts. 9−15 In the extreme case, catalysts contain these precious metals in an atomically dispersed form, which in recent years has become a topic of frontier research.…”

Ba-addition induced enhanced surface reducibility of SrTiO3: implications on catalytic aspects

“…57,58 There have been a few reports exploring the photocatalytic activity and the effect of the size and morphology of the supported nanoparticle. [59][60][61] Our observation of enhancement of catalytic activity by adding Ba to the SrTiO 3 support suggests that it could be an ideal system to obtain interesting insights into the interplay between oxygen vacancies, catalyst pre-treatment and catalytic activity.…”

Cu–Cu2O Heterogeneous Architecture for the Enhanced CO Catalytic Oxidation

“…Although noble metals (such as Au, Ag, and Ru) exhibit highly CO oxidation activities,17–19 the rare quantity and high cost restrict their application. In contrast, transition metal oxides are of interest as the most suitable substitutes owing to the low cost and abundance.…”

“…However, few appeared reports have concerned about the CO catalytic activity of Cu–Cu 2 O interface in oxygen atmospheres. From the previous theoretical perspective, the role of the loading particles focuses on the variations in work functions, the polarization at the interface of hybrid material, and the regulating and controlling of oxygen vacancy 17,25. The lack of Cu–Cu 2 O heterogeneous interface and molecular understanding during the catalytic process remain unclear.…”