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Doping Pd atoms in NC/Au monomers (nitrogen-doped carbon-supported gold monomers) requires precise control of the synthesis method to introduce Pd atoms into the Au monomer sites or adjacent positions while maintaining monomer dispersion. The following are the specific methods and steps:
1) Co-impregnation - pyrolysis method
Mix the Au precursor (such as HAuCl₄) and Pd precursor (such as PdCl₂ or Pd(NO₃)₂) in the desired ratio (e.g., Au:Pd = 1:1). Add the nitrogen-doped carbon carrier (such as ZIF-8-derived NC or commercial NC materials). Impregnation and drying: Stir/sonicate to allow the metal precursors to uniformly adsorb on the carrier, followed by freeze-drying or vacuum drying.
Pyrolysis reduction: Pyrolyze at 300–800°C in an inert atmosphere (Ar/N₂) to reduce and anchor the Au and Pd atoms at the NC defect sites.
Key point: Low temperature (<500°C) is conducive to the formation of monomers, while high temperature may lead to the formation of Pd-Au clusters. The dual solvent method (such as ethylene glycol/water) can be used to improve metal dispersion.
2) Atomic layer deposition (ALD) method
First, deposit Au monomers (such as using Me₂Au(acac) precursor) on the NC. Then, deposit Pd monomers (such as Pd(hfac)₂) using the same method. Promote the cooperative dispersion of Pd and Au at the sites through low-temperature annealing (200–300°C). Advantage: Precisely control the Pd/Au ratio (layer-by-layer regulation).
