Self-assembled fabrication of a polycrystalline boron-doped diamond surface supporting Pt (or Pd)/Au-shell/core nanoparticles on the (111) facets and Au nanoparticles on the (100) facets

Modified boron-doped diamond (BDD) surfaces supporting different, carefully selected types of metal nanoparticles on different types of crystal facets were fabricated via a self-assembly method. A hydrogen plasma-treated BDD surface was treated with UV/ozone for 10 s followed by immersion in a Au nanoparticle (AuNP) solution to fabricate a BDD surface selectively and densely supporting AuNPs on the (111) facet (AuNP111-BDD). The AuNP111-BDD sample was then immersed in H2PtCl6/ascorbic acid or H2PdCl4/sodium citrate to cover the AuNP surface with Pt or Pd (Pt/AuNP111-BDD or Pd/AuNP111-BDD). These samples were treated with UV/ozone for 40 s followed by re-immersion in the AuNP solution to immobilize AuNPs on the (100) facets (Pt/AuNP111–AuNP100-BDD or Pd/AuNP111–AuNP100-BDD). The metal nanoparticles supported on the BDD surface were confirmed by cyclic voltammetry to be electrochemically active. The crystal-facet-selective support of the metal nanoparticles was also confirmed by two-dimensional elemental mapping via field emission Auger electron spectroscopy. The macro procedures used for the crystal-facet-selective immobilization of the AuNPs was reproducible, and this technique should be applicable to the creation of a new class of advanced materials in such fields as optics, electronics, sensing, and (electro)catalysis.

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► Crystal-facet-selective metal NP-modified BDD surfaces were fabricated.
► Pt (or Pd)/AuNP and AuNP were supported on the (111) and (100) facets selectively.
► The electrochemical activity of each type of NP on the surface was confirmed.
► Elemental mapping with FE-AES also indicated the crystal-facet-selective supporting.