Imaging the facet surface strain state of supported multi-faceted Pt nanoparticles during reaction

Abstract

Nanostructures with specific crystallographic planes display distinctive physico-chemical properties because of their unique atomic arrangements, resulting in widespread applications in catalysis, energy conversion or sensing. Understanding strain dynamics and their relationship with crystallographic facets have been largely unexplored. Here, we reveal in situ, in three-dimensions and at the nanoscale, the volume, surface and interface strain evolution of single supported platinum nanocrystals during reaction using coherent x-ray diffractive imaging. Interestingly, identical {hkl} facets show equivalent catalytic response during non-stoichiometric cycles. Periodic strain variations are rationalised in terms of O2 adsorption or desorption during O2 exposure or CO oxidation under reducing conditions, respectively. During stoichiometric CO oxidation, the strain evolution is, however, no longer facet dependent. Large strain variations are observed in localised areas, in particular in the vicinity of the substrate/particle interface, suggesting a significant influence of the substrate on the reactivity. These findings will improve the understanding of dynamic properties in catalysis and related fields.

Development of nanoparticle bulk morphology analysis: a multidomain XRD approach

“…S5), than the 200 peak. We assume that it is caused by the fact, that [200] direction has a small multiplicity (8). Whereas the [220] direction has 12 orientations allowing better domain size averaging.…”

“…However, their influence on the nanoparticles properties is often neglected. As shown by a number of experimental studies, microstrains affect the catalytical properties of NPs [7][8][9][10][11] . Meanwhile, theoretical predictions of catalytical activity do not take into account the effect of elastic strains 12,13 .…”

Insights into Heterogeneous Catalysts under Reaction Conditions by In Situ/Operando Electron Microscopy

“…Many in situ/operando FTIR (Fourier transform infrared spectroscopy), Raman, XAS (X‐ray absorption spectroscopy), XPS (X‐ray photoelectron spectroscopy), XRD (X‐ray diffraction), etc., have been used for catalyst characterizations which largely capture the average molecular or atomic information under reaction conditions. [ 22–47 ] In comparison, in situ/operando TEM is relatively new, which enables the ability to capture individual atom or molecule information under the reaction conditions. In other words, it provides information with atomic, molecular and sometimes nanoscale/microscale resolutions depending on the complexity of the sample system and the instrumental measurement configuration.…”

Reversible Ultrathin PtOx Formation at the Buried Pt/YSZ(111) Interface Studied In Situ under Electrochemical Polarization

“…First of all, the used temperature is about 350 K lower than the deposition temperature. Furthermore, typical conditions needed for extensive mass transport of Pt on oxides are temperatures above 1300 K for extensive times of 24 h . Once a thick, closed, and relaxed Pt film has formed at deposition temperature, it will remain morphologically stable at the used experimental temperatures.…”

“…First of all, the used temperature is about 350 K lower than the deposition temperature. Furthermore, typical conditions needed for extensive mass transport of Pt on oxides are temperatures above 1300 K for extensive times of 24 h. 37 Once a thick, closed, and relaxed Pt film has formed at deposition temperature, it will remain morphologically stable at the used experimental temperatures. During anodic polarization, oxygen gas can form at the Pt/YSZ interface and the pressure can increase up to several tens of bars, perhaps even 10–100 times higher during the initial platinum detachment, inside the blisters.…”