UV–Ozone Cleaning of Supported Poly(vinylpyrrolidone)-Stabilized Palladium Nanocubes: Effect of Stabilizer Removal on Morphology and Catalytic Behavior

Abstract

Poly(vinylpyrrolidone) (PVP)-stabilized Pd nanocubes were synthesized, deposited on a carbon-based support, and subsequently treated with UV-ozone (UVO) in order to eliminate the traces of PVP still present on the surface. Cubes, being a thermodynamically unfavorable shape, are very prone to restructuring to minimize the interfacial free energy and thus allow the assessment of their morphological stability during UVO cleaning. The process of PVP removal was monitored by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and in situ attenuated total reflection infrared spectroscopy (ATR-IR). High-resolution scanning electron microscopy (SEM) imaging was used to evaluate the morphology of the nanocubes. The effect of PVP removal was also studied in the hydrogenation of acetylene, showing a 4-fold increase of activity. This method can be applied to nanoparticles of other common shapes, which expose different crystal planes, in order to study the structure sensitivity of chemical reactions.

Shape-Dependence of Pd Nanocrystal Carburization during Acetylene Hydrogenation

“…2.5 nm 44 ) above which size does not significantly impact carbide formation. It is worth noting that the morphology of shape-controlled nanocrystals under similar reaction conditions was not affected as shown in a previous study, 45 and therefore, the shape and size of the nanocrystals used in this study is most probably preserved throughout the duration of the in situ measurements.…”

Electrocatalysis on shape-controlled metal nanoparticles: Progress in surface cleaning methodologies

“…In fact, these electrochemical tools have been shown to be extremely sensitive to analyse possible perturbations of the surface structure of the nanoparticles when too aggressive decontamination protocols are employed. In this way, it was possible to evidence that the use of UV/ozone as decontamination protocol [25][26][27] resulted in an important surface structure perturbation but without affecting neither the size nor the shape of the nanoparticles as deduced from TEM measurements [28 ].…”

Controllable Catalysis with Nanoparticles: Bimetallic Alloy Systems and Surface Adsorbates

“…Thus, a variety of surface treatment protocols for the removal of adsorbates have been developed to yield pristine NP surfaces for catalytic applications. [15][16][67][68][69][70] However, the "naked" NPs are not always optimal catalysts. The influence of adsorbates on the catalytic properties of NPs can be salutary, resulting in improved or modified chemoselectivities and increased reaction rates.…”