Our group has employed the thiosulfate protocol, using sodium S-alkylthiosulfates instead of alkanethiols, to generate catalytically active Pd nanoparticles (PdNP) capped with the lower density of alkanethiolate ligands. The controlled alkanethiolate capping has provided nanoparticles the partial poisoning necessary for selective hydrogenation and/or isomerization of olefins. To further increase the utility of Pd nanoparticle catalysts, the colloidal hybrids of PdNP with graphene quantum dots (GQD) and bismuth selenide (Bi2Se3) nanodiscs (BSD) were prepared. It has been found that significant enhancement of photocatalytic efficiency is achieved by the deposition of noble metal nanoparticles on the semiconductor particle surfaces, since metal acts as a reservoir for photogenerated electrons or holes and promotes interfacial charge separation processes. Our research hypothesizes that the transferred electrons or holes created by the semiconductor supports might have strong effects on the catalytic activity and selectivity of colloidal PdNP. GQD was found to be an excellent UV-active semiconductor, with its optical and electronic properties induced by the quantum confinement effect. The strong near-infrared (NIR) absorption of Bi2Se3 nanodiscs also allowed to utilize a solar spectrum to generate electrons and holes. Photo-enhanced catalysis of PdNP-GQD and PdNP-BSD hybrids was investigated for understanding the effect of photo-generated electrons or holes in the activity of PdNP using the model alkene hydrogenation reaction. The ligand-capped PdNP, PdNP/GQD, and PdNP/BSD were characterized using UV-vis spectroscopy, fluorescence spectroscopy, Raman spectroscopy, and transmission electron microscopy (TEM). The catalytic alkene hydrogenation was monitored using gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR).

Pd nanoparticle-quantum dot nanodisc hybrids for photo-enhanced colloidal catalysis

2019 Fall National Meeting

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