Lattice Strained Bimetallic PtPd Nanocatalysts Display Multifunctional Nature for Transfer Hydrogenolysis of Sorbitol in Base-Free Medium

Abstract Catalytic transfer hydrogenolysis of polyols by in-situ formed H2 under mild reaction conditions, displays both technological and environmental advantages over conventional hydrogenolysis processes operating at elevated temperatures and pressures. Current studies on catalyst design are primarily focused on compositional features of solid catalysts to obtain superior activity and selectivity to value added products. A major challenge is to understand the electronic nature of catalysts in C-H, C-C and C-O cleavage of polyols. In this work, we report a design principle for modulating lattice and electronic configuration of bimetallic PtPd/NMC catalysts, immobilized on N-doped carbon, for highly efficient transfer hydrogenolysis of sorbitol to renewable glycols and alcohols in base-free medium. The finding is that lattice strain and electronic coupling at metal-N interface induce confined growth of PtPd crystal facets, leading to strained structures with Pt lattice contraction and Pd phase segregation. While conventional PtPd nanoparticles exhibit monofunctional nature in facilitating C-H cleavage of sorbitol with poor activity, such unique PtPd/NMC catalysts display a synergistic four-fold activity enhancement (TOF: 58 h-1 at 200 oC) for tandem C-H, C-C and C-O cleavage of polyols. Chemisoprtion and XPS spectroscopy studies reveal that N-doped carbon functions as a Lewis base and lattice modulator to manipulate electronic properties of bimetallic nanocatalysts, for facile tandem C-H (H2 generation) and C-O/C-C cleavage (hydrogenolysis) catalysis.