Non-noble metal (NNM) intermetallic compounds (IMCs) produced from transition metals bound with early p-block elements are rapidly rising as highly tunable catalysts that exhibit a far greater range of surface chemistry in comparison to pure or alloyed platinum group metal catalysts. The origins of the special low surface chemistry toward and attenuated hydrogenation kinetics of C═C bonds of NNM late-TM IMCs was determined to be associated with the strength and degree of d-/p-state hybridization in prior studies. However, the systematic trends in their surface chemistry toward C═O hydrogenation remained undetermined. This study focuses on identifying electronic properties and physical phenomena (electrostatic and redox properties) of IMCs that control surface chemistry in the demanding chemistry of selective hydrogenation of unsaturated aldehyde (cinnamaldehyde). The study has discovered that prior trends in bonding within the IMC and C═C hydrogenation also apply to C═O hydrogenation but are modified further by adsorption-induced reduction that stabilizes reaction intermediates. Additionally, proposed favorable electrostatic interactions that direct adsorbate geometry were refuted through the direct study of electric field effects at the location of the C═O moiety. At a greater level, results illustrate an ability to more individually tune surface chemistry and hydrogenation selectivity of C═C and C═O bonds compared to pure metals, which will greatly accelerate the rational design of inexpensive NNM IMC catalysts for a large number of classic and contemporary reactions.
Guo et al. (Mon,) studied this question.