In the first part of this work, we reveal the complexity of commercially available platinum-based electrocatalysts and their electrochemical behavior. In the second part, we introduce a bottom-up approach where atomically resolved properties, structural changes, and strain analysis are recorded as well as analyzed on an individual nanoparticle before and after electrochemical conditions (e.g. high current density). Our methodology offers a new level of understanding of structure-stability relationships of practically viable nanoparticulate systems.
COBISS.SI-ID: 49660163
The present study showcases the importance of temperature and potential window for evaluation of Pt-based supported electrocatalyst stability. A platinum based commercial material with an average size of Pt nanoparticles between 2-3 nm (Pt/C) and its thermally annealed analogue with an average particle size of ~5 nm (Pt/C-HT) are considered. X-ray diffraction (XRD), ex situ transmission electron microscopy (TEM) imaging and thin film rotating disc electrode (TF-RDE) along with proprietary high-temperature disc electrode (HT-DE) are used for electrocatalysts inspection. The study shows a clear dependence between the electrochemical surface area (ECSA) loss and the temperature increase during the potentiodynamic accelerated degradation test (ADT). Additionally it is demonstrated that selection of the lower and upper potential limits in ADT protocol plays an important role in ECSA loss. Comparing various results obtained on Pt/C and Pt/C-HT, we show that varying ADT conditions of temperature and different potential windows is crucial for adequate evaluation and stability interpretation of potentially promising novel electrocatalysts and that relatively mild ADT conditions (i.e. 0.4-1.0 VRHE, RT) can be potentially misleading.
COBISS.SI-ID: 23888131
A modified floating electrode (MFE) approach for investigating the electrochemical phenomena at a gas/electrode/liquid reaction interface is introduced. Such investigation is in sharp contrast to conventional electrochemical techniques, which measure the properties of electrode/liquid interfaces. MFE is based on an apparatus that enables electrocatalytic conversion under enhanced mass transport of reactant gas. This is enabled by the floating regime of the working electrode that presents a low mass transport barrier for the gas. The present MFE is designed to take the advantage of transmission electron microscopy (TEM) grids with a deposited electrocatalyst of choice, to be used as working electrodes.
COBISS.SI-ID: 39249411