%AFarrag, Mostafa [Department of Chemistry Virginia Commonwealth University Richmond VA 23284-2006 USA, Nanoclusters and Photocatalysis Laboratory Chemistry Department Faculty of Science Assiut University Asyut 71516 Assiut Egypt]%ADas, Mrinmoy [Department of Chemistry Virginia Commonwealth University Richmond VA 23284-2006 USA]%AMoody, Michael [Department of Chemistry Virginia Commonwealth University Richmond VA 23284-2006 USA]%ASamy El‐Shall, M. [Department of Chemistry Virginia Commonwealth University Richmond VA 23284-2006 USA]%BJournal Name: ChemPhysChem; Journal Volume: 22; Journal Issue: 3; Related Information: CHORUS Timestamp: 2023-09-02 16:39:55 %D2020%IWiley Blackwell (John Wiley & Sons) %JJournal Name: ChemPhysChem; Journal Volume: 22; Journal Issue: 3; Related Information: CHORUS Timestamp: 2023-09-02 16:39:55 %K %MOSTI ID: 10257649 %PMedium: X %TLigand‐Protected Ultrasmall Pd Nanoclusters Supported on Metal Oxide Surfaces for CO Oxidation: Does the Ligand Activate or Passivate the Pd Nanocatalyst? %XAbstract

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.

%0Journal Article