Facet Preferencing by Chemical Substitution Controls Semi-Hydrogenation Selectivity in Ternary Pyrite-Type...

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• Intermetallic compounds are valuable model catalysts for selective hydrogenation.
• Tuning active site composition, geometry, and electronic structure is key to catalyst design.
• Introducing a third element can alter exposed crystal facets, improving catalytic behavior.

Purpose of the Study:

• To investigate the effect of site-specific substitution on facet exposure in intermetallic catalysts.
• To demonstrate a strategy for indirectly modifying active sites via preferential facet exposure.
• To enhance catalytic performance in selective hydrogenation reactions.

Main Methods:

• Synthesis of ternary intermetallic compounds (Pd$_{1-x}$Au$_x$Sb$_2$).
• Characterization using electron backscattered diffraction.
• Computational analysis using density functional theory (DFT).

Main Results:

• Substitution of Pd with Au in PdSb$_2$ led to preferential exposure of the (100) facet over the (111) facet.
• DFT calculations confirmed the facet change induced by Au substitution.
• The (100) facet exhibited higher net alkene selectivity due to weaker alkene binding.

Conclusions:

• Site-specific substitution is an effective strategy for controlling facet exposure in intermetallic catalysts.
• Preferential exposure of the (100) facet enhances selectivity in hydrogenation reactions.
• This work highlights indirect modification of active sites through facet engineering.