Bimetallic monolayer catalyst breaks the activity–selectivity trade-off on metal particle size for efficient chemoselective hydrogenations

Particle size governs the geometric and electronic structure of metal nanoparticles (NPs), shaping their catalytic performance. However, size-dependent entanglement in the geometric and electronic structures often leads to a trade-off between activity and selectivity, limiting the optimization of the overall catalytic performance. Here we show that precisely controlled deposition of a platinum monolayer on large gold NPs breaks the activity–selectivity trade-off on particle size in platinum-catalysed chemoselective hydrogenation of halonitrobenzenes, resulting in a remarkable activity, along with a 99% selectivity for haloanilines under mild conditions. The high activity results from upshift of the platinum 5d-band centre through platinum lattice expansion and ligand effect, whereas the high selectivity is caused by exposing more terrace sites on large particles. The geometric and electronic properties of bimetallic monolayer materials, distinct from monometallic NPs and alloys, constitute a promising platform for the rational design of metal catalysts with superior performance in hydrogenation reactions. Chemoselective reactions are often characterized by an activity–selectivity trade-off that renders their optimization difficult. Here gold nanoparticles equipped with a platinum monolayer are introduced that, thanks to lattice expansion and ligand effect, achieve a remarkable performance for the chemoselective hydrogenation of halonitrobenzenes