文摘
Platinum nanoparticles (NPs) capped with polyvinylpyrrolidone (PVP) were studied with sum frequency generation (SFG) vibrational spectroscopy under reaction conditions during cyclohexene (CH) and 1,4-cyclohexadiene (1,4-CHD) hydrogenation at 295 K. Despite similar vibrational features observed during reaction, CH and 1,4-CHD proceed through mutually exclusive pathways on 1.7 and 4.6 nm Pt-PVP NPs unlike Pt(111) studied previously. The intense red-shifted C–H stretch of adsorbed 1,4-CHD at 2770 cm–1 was monitored for both reactions. SFG and kinetic experiments show CH hydrogenation is active and reversible, while 1,4-CHD hydrogenation poisons the surface.