Search

Hydrogen spillover is an important theme for hydrogen storage and H-involving catalytic reactions. This work shows that catalytic reactivity and selectivity can be revealed by differentiating the energetic characteristics of spilled H species. With the assistance of Ti, F and C in MXenes, Pd1.8Ni@Ti3C2Txpresents a high capacity for spillover hydrogen storage at ambient temperatures, and the rich oxygenated groups act as the main carriers of hydrogen spillover around metal nanoparticles. Thermodynamic analysis reveals that the catalytic performances are energetically dominated by the adsorption enthalpies of the active spilled H species rather than the amount of spillover hydrogen, and can be tuned by alloying and surface modification. The ideas are verified from the excellent catalysis, chemoselectivity and stereoselectivity of Pd1.8Ni@Ti3C2Txin semihydrogenations. The strategy of maximizing catalytic performances is applicable to other Pd-based bimetals@Ti3C2Tx, such as Pd2.6Co@Ti3C2Txand Pd1.5Fe@Ti3C2Tx, and provides new energetics perspectives to understand the catalytic mechanism in spillover-involving chemical procedures.

The selective semihydrogenation of alkynes is of importance in many industrial applications, but great challenges still remain in the full utilization of noble metals for the catalysis of hydrogen spillover on mixed supports. As Pd0is chemically loaded on Cu2O/TiO2, this work reports that Pd0is imparted with a high electron density to dissociate H2efficiently and the active Cu2O hydride is responsible for the high catalytic activity in spillover semihydrogenations. As compared with inert Pd–Cu2O/SiO2interfaces, the studies demonstrate that the high chemoselectivity and stereoselectivity originate from the well-defined p–n junctions of Cu2O/TiO2, therein alkynes are adsorbed in their transconfigurations and the product is desorbed from them. As catalyzed by 1.3Pd–3.6Cu2O/TiO2in 1 atm H2at 30 °C, the semihydrogenations can be completed in 90 min with 97.6% chemoselectivity for phenylacetylene, and in 45 min with 92.4% stereoselectivity for methyl non-2-ynoate. These studies provide new ideas to design and synthesize noble metal-based catalysts through manipulating the interface properties of the mixed supports.