Verification of Organic Capping Agent Removal from Supported Colloidal Synthesized Pt Nanoparticle Catalysts

摘要

The synthesis and application of colloidal metal nanoparticles as catalyst components are emerging research areas with potential to revolutionize the field of heterogeneous catalysis due to the ability to achieve simultaneous size, shape, and composition control and thus defined active sites. This contribution evaluates the role of the synthetic strategy on the catalytic properties of polymer stabilized Pt nanoparticles supported on silica and titania. Temperature-programmed oxidation (TPO) profiles confirmed that triple washings in ethanol/hexanes cycles removed the majority of organic species. Ethylene hydro-genation demonstrated that the turnover frequencies match the expected literature values at near ambient conditions. Finally, catalytic methanol decomposition and methanol oxidation showed differences with the support, which inferred that the Pt-support interface is free from organic impurities that would block the metal-support interactions. Moreover, ongoing studies on photocatalytic decomposition with titania showed enhancements with the addition of Pt and this result again supports the existence of the Pt-support interface. Together, these methodologies provide both an array of techniques to probe the role of the organic capping layers and a comprehensive demonstration that these systems are relatively free from organic capping interference with the optimized synthesis and purification protocols.