Explaining the Size Dependence in Platinum‐Nanoparticle‐Catalyzed Hydrogenation Reactions

Abstract

Hydrogenation reactions are industrially important reactions that typically require unfavorably high H2 pressure and temperature for many functional groups. Herein we reveal surprisingly strong size‐dependent activity of Pt nanoparticles (PtNPs) in catalyzing this reaction. Based on unambiguous spectral analyses, the size effect has been rationalized by the size‐dependent d‐band electron structure of the PtNPs. This understanding enables production of a catalyst with size of 1.2 nm, which shows a sixfold increase in turnover frequency and 28‐fold increase in mass activity in the regioselective hydrogenation of quinoline, compared with PtNPs of 5.3 nm, allowing the reaction to proceed under ambient conditions with unprecedentedly high reaction rates. The size effect and the synthesis strategy developed herein may provide a general methodology in the design of metal‐nanoparticle‐based catalysts for a broad range of organic syntheses.

A Review on Particle Size Effect in Metal‐Catalyzed Heterogeneous Reactions

“…In hydrogenation of quinolone, Gao and co‐workers reported a volcano‐shape activity on Pt/SiO 2 catalysts with the Pt particle size in the range of 0.7—5.3 nm, where the maximum was observed at the Pt size of 1.2 nm (Figure 15A). [ 102 ] With XPS and UPS measurements (Figures 15B and C), they found a clear shift of the d‐band center towards the valence band maximum (VBM) and higher d‐band vacancy with decreasing Pt particle size, which both lead to a stronger interaction between Pt and guest molecules. Thus, they attributed the volcano‐shape activity to the size‐dependent d‐band electronic structure of Pt NPs and thus their varied interactions with reactants based on the Sabatier's principle.…”

Size-dependent activity and selectivity of carbon dioxide photocatalytic reduction over platinum nanoparticles

“…With the decrease in particle size, the proportion of the low-coordinated surface sites (corner or edge) increased 14 , 15 . In addition, the metal oxidation states also exhibited size-dependent properties 16 , 17 . Therefore, a good understanding of the size-dependent activity of Pt has been demonstrated in many catalytic reactions, such as ammonia borane dehydrogenation 14 , 18 , regioselective hydrogenation of quinolone 16 , and the oxygen reduction reaction 15 , among others.…”

“…In addition, the metal oxidation states also exhibited size-dependent properties 16 , 17 . Therefore, a good understanding of the size-dependent activity of Pt has been demonstrated in many catalytic reactions, such as ammonia borane dehydrogenation 14 , 18 , regioselective hydrogenation of quinolone 16 , and the oxygen reduction reaction 15 , among others. Recently, size-dependent activity and selectivity in the CO 2 electrocatalytic reduction reaction (CO2RR) have been reported for metal NPs, such as Pd, Au and Cu, due to the intrinsic free energy of key intermediate evolutions on different surface sites 19 – 21 .…”

Pd–Ni nanoparticles supported on reduced graphene oxides as catalysts for hydrogen generation from hydrazine

“…Ultra-small metal nanocatalysts (<7 nm) have received substantial attention, because they show high catalytic efficiencies in numerous reactions. [29][30][31][32][33] However, the broad particle size distribution and the aggregation of metal NPs during reaction limit their applications. Supports can be used to solve this problem.…”