Nucleation of Monolayer Catalyst Obtained By Slrr of UPD Monolayer
Authors: Brankovic Stanko 
Published: May 2020

Catalyst MLs have been extensively studied and their catalytic properties depend on the interplay between the host metal and the ML overlayer.1–8 Ideal ML catalysts are difficult to synthesize and often exhibit defect structures that may contribute to their catalytic activity.12 The most common example is Pt and, at room temperature, Pt is very difficult to deposit in a true continuous ML configuration.13 Hence, the sub-monolayer (sML) configuration is dominant. Functional Pt sML catalysts have a morphology consisting of compact 2D nanoclusters with certain size distribution and coverage of the substrate.14–17 Due to finite size effects,18,19 the local strain in Pt nanoclusters (l) is a combination of the coherent strain and the strain caused by the finite size effects. Therefore, the finite size effect represents a phenomenon that can be used as additional knob to fine-tune the d-band energy of the ML catalysts, which inherently controls overall catalytic activity. Turning this knob in desired direction by varying nanocluster sizes requires a better understanding of the conditions during ML catalyst synthesis, which are responsible for nanocluster nucleation and size control.
In the first part of the talk we will review several examples of the finite size effects on activity of ML catalyst as a prelude to the discussion about how to control catalyst ML nucleation and morphology. The special emphasis is on identifying effective approach to control and manipulate conditions during ML catalyst synthesis via SLRR of UPD ML which result in desired nanocluster size, nucleation density and overall ML morphology. The analytical model describing the fundamental link between the nucleation kinetics and reaction kinetics of SLRR is discussed. Further on, the link between the SLRR process parameters such as choice of UPD ML, concentration of metal ions, temperature, mixing and concentration of supporting electrolyte in solution for SLRR will be discussed within the frame work of the models describing the SLRR reaction kinetics and their link to the resulting catalyst ML morphology.
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