Designed synthesis and formation mechanism of CeO₂hollow nanospheres and their facile functionalization with Au nanoparticles

Abstract

In this work, a facile one-step solvothermal method with the assistance of hydrochloric acid has been developed to prepare well-dispersed CeO 2 hollow nanospheres with high surface areas. The effects of 10 hydrochloric acid on the growth mechanism and the size distribution are investigated in detail. It is found that the hydrogen ions expedite the nucleation rate of the CeO 2 nuclei in the nucleation course while the chloride ions accelerate the Ostwald ripening in the acidic environment. Both the hydrogen ion (H + ) and the chloride ion (Cl -) are confirmed to play a key role in the formation of hollow morphology. Based on our experiments, a HCl-assisted oxidation-nucleation with Ostwald ripening process mechanism was 15 proposed. Furthermore, the Au nanoparticles with a size of 2.5-6 nm were uniformly deposited on the surface of ceria support by a simplified reduction process with the sodium borohydride (NaBH 4 ). The synthesized Au/CeO 2 nanospheres exhibit a higher catalytic activity in CO oxidation than pure ceria nanospheres-due to the existence of different Au species (metallic Au 0 and positively charged Au δ+ )and the strengthened interfacial interactions between the Au NPs and the ceria support.

The Synthesis of SiO2@AuAg@CeO2 Sandwich Structures with Enhanced Catalytic Performance Towards CO Oxidation

“…As inspired by the fact above, the SACs were designed and prepared with a view to improve the catalytic performance by integrating the advantage of the sandwich structure and bimetallic alloy. CeO 2 was chosen as the attractive shell due to its unique redox properties . As shown in Figure , the novel synthetic procedure of the SACs involves preparation of SiO 2 nanospheres as support, adsorbing the AuAg alloy nanoparticles on the SiO 2 , and coating the CeO 2 shell entirely over the supported nanostructures.…”

“…And the CeO 2 shell can fully protect the AuAg nanoparticles from sintering and aggregation during the catalytic process. A comparison of the catalytic performances for CO oxidation between the previously reported catalysts and SACs was shown in Table S1, [16,22,34,[36][37][38] from which the excellent low-temperature catalytic activity of SACs is clearly observed.…”

“…CeO 2 was chosen as the attractive shell due to its unique redox properties. [22][23][24] As shown in Figure 1, the novel synthetic procedure of the SACs involves preparation of SiO 2 nanospheres as support, adsorbing the AuAg alloy nanoparticles on the SiO 2 , and coating the CeO 2 shell entirely over the supported nanostructures. Compared with the supported and monometallic catalysts, the as-obtained SACs exhibit much improved low-temperature catalytic activity and high-temperature thermal stability in CO oxidation.…”

Hollow Micro/Nanostructured Ceria‐Based Materials: Synthetic Strategies and Versatile Applications

“…[59] Similarly, CeO 2 with hollow structures show superiority on ethanol reforming reactions as well. [156] Similarly, besides CeO 2 HSs, CeO 2 NTs can be used as support for Au NPs and showed improved CO oxidation performance. Compared with catalysts with CeO 2 particles, Zr-doped CeO 2 NTs based catalysts are more active for hydrogen reduction and ethanol reforming, which might result from a higher proportion of exposed {100} and {110} high-energy active facets within NTs relative to CeO 2 NPs.…”

Au/CeO2 Catalysts: Structure and CO Oxidation Activity

“…The Au/CeO 2 nanorods (110 + 100) and Au/CeO 2 nanopolyhedra (111 + 100) showed higher activity than Au nanocube (100) catalysts. A one-step hydrochloric acid-assisted solvothermal method for the preparation of well-dispersed CeO 2 hollow nanospheres with high surface area and its decoration by colloidal Au nanoparticles were reported by Liu et al [124]. According to the authors, this method leads to the existence of different Au species, both metallic and positively charged, which strengthened the interface interactions with the support.…”