Herein, we report on the synthesis of ultrasmall Pd nanoclusters (∼2 nm) protected by L‐cysteine [HOCOCH(NH2)CH2SH] ligands (Pdn(L‐Cys)m) and supported on the surfaces of CeO2, TiO2, Fe3O4, and ZnO nanoparticles for CO catalytic oxidation. The Pdn(L‐Cys)mnanoclusters supported on the reducible metal oxides CeO2, TiO2and Fe3O4exhibit a remarkable catalytic activity towards CO oxidation, significantly higher than the reported Pd nanoparticle catalysts. The high catalytic activity of the ligand‐protected clusters Pdn(L‐Cys)mis observed on the three reducible oxides where 100 % CO conversion occurs at 93–110 °C. The high activity is attributed to the ligand‐protected Pd nanoclusters where the L‐cysteine ligands aid in achieving monodispersity of the Pd clusters by limiting the cluster size to the active sub‐2‐nm region and decreasing the tendency of the clusters for agglomeration. In the case of the ceria support, a complete removal of the L‐cysteine ligands results in connected agglomerated Pd clusters which are less reactive than the ligand‐protected clusters. However, for the TiO2and Fe3O4supports, complete removal of the ligands from the Pdn(L‐Cys)mclusters leads to a slight decrease in activity where the T100%CO conversion occurs at 99 °C and 107 °C, respectively. The high porosity of the TiO2and Fe3O4supports appears to aid in efficient encapsulation of the bare Pdnnanoclusters within the mesoporous pores of the support.
Gold (Au)- and ceria (CeO2)-based catalysts are amongst the most active catalysts for the gas phase CO oxidation reaction. Nevertheless, nanosized Au and CeO2catalysts may encounter heat-induced sintering in thermochemical catalytic reactions. Herein, we report on the rational one-pot synthesis of ceria-reduced graphene oxide (CeO2-RGO) using a facile ethylenediamine (EDA)-assisted solvothermal method. Standalone RGO and free-standing CeO2were also prepared using the same EDA-assisted method for comparison. We then incorporated Au into the prepared samples by colloidal reduction and evaluated the catalytic activity of the different catalysts for CO oxidation. The RGO-supported CeO2surpassed the free-standing CeO2, exhibiting a 100% CO conversion at 285oC compared to 340oC in the case of CeO2. Interestingly, the RGO-supported Au/CeO2catalysts outperformed the Au/CeO2catalysts and achieved a 100% CO conversion at 76oC compared to 113oC in the case of Au/CeO2. Additionally, the Au/CeO2-RGO catalyst demonstrated remarkable room-temperature activity with simultaneous 72% CO conversion. This outstanding performance was attributed to the unique dispersion and size characteristics of the RGO-supported CeO2and Au catalysts in the ternary Au/CeO2-RGO nanocomposite, as revealed by TEM and XPS, among other techniques.
more » « less- Award ID(s):
- 1900094
- NSF-PAR ID:
- 10397632
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Materials Research Express
- ISSN:
- 2053-1591
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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