Abstract
The selective enhancement of catalytic activity is a challenging task, as catalyst modification is generally accompanied by both desirable and undesirable properties. For example, in the case of the direct synthesis of hydrogen peroxide, Pt on Pd improves hydrogen conversion, but lowers hydrogen peroxide selectivity, whereas Au on Pd enhances hydrogen peroxide selectivity but decreases hydrogen conversion. Toward an ideal catalytic property, the development of a catalyst that is capable of improving H-H dissociation for increasing H2 conversion, whilst suppressing O-O dissociation for high H2O2 selectivity would be highly beneficial. Pd-core AuPt-bimetallic shell nanoparticles with a nano-sized bimetallic layer composed of Au-rich or Pt-rich content with Pd cubes were readily prepared via the direct seed-mediated growth method. In the Pd-core AuPt-bimetallic shell nanoparticles, Au was predominantly located on the {100} facets of the Pd nanocubes, whereas Pt was deposited on the corners of the Pd nanocubes. The evaluation of Pd-core AuPt-bimetallic shell nanoparticles with varying Au and Pt contents revealed that Pd-core AuPt-bimetallic shell that was composed of 2.5 mol% Au and 5 mol% Pt, in relation to Pd, exhibited the highest H2O2 production rate (914 mmol H2O2 gmetal−1 h−1), due to the improvement of both H2O2 selectivity and H2 conversion.
Highlights
The fabrication of core–shell nanostructures that are composed of a partially or fully enveloping shell located on the surface of a nanostructured core material has been implemented for the enhancement of catalyst properties [1,2,3]
Core–shell nanoparticles comprised of a Pd nanocube core and a AuPt bimetallic shell were synthesized via a direct seed-mediated growth approach, which was achieved by the simultaneous
Core–shell nanoparticles comprised of a Pd nanocube core and a AuPt bimetallic shell were the need for washing during synthesis
Summary
The fabrication of core–shell nanostructures that are composed of a partially or fully enveloping shell located on the surface of a nanostructured core material has been implemented for the enhancement of catalyst properties [1,2,3]. Four PtNi atomic layers presented a five-fold increase in oxygen reduction reaction (ORR) activity as compared to conventional Pt/C catalyst, as well as enhanced stability [5]. Pd core nanocrystals that are encapsulated by isolated Ptand Au-promoted domains are expected to produce an advanced catalyst for the DSHP reaction by enhancing H2 conversion and increasing H2 O2 selectivity. We report a facile aqueous-phase synthesis of Pd-core AuPt–bimetallic shell nanoparticles and their application as DSHP reaction catalysts, wherein enhanced selectivity and activity were observed for direct H2 O2 production. In the synthesized core–shell nanoparticles, Au was predominantly located on the Pd (100) terrace surface, whereas Pt was generally deposited on the corners of the Pd nanocubes, which indicated the successful formation of a AuPt bimetallic shell
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