Facet-dependent electrocatalysis and surface electrochemical processes on polycrystalline platinum

Deciphering the Interplay between Local and Global Dynamics of Anodic Metal Oxidation

“…Intriguingly, the direction of polishing seems to exert minimal influence on this pattern’s distribution. Areas exhibiting a polygonal shape and sizes smaller than 10 μm (circled for emphasis) notably sustain a lighter hue, which closely resembles the metal crystallographic texture. − It is crucial to mention that our experiment utilized pure Fe, effectively eliminating chemical heterogeneities as a potential explanation for the observed patterning.…”

“…Recent advancements in the development and application of local probe techniques have highlighted the pronounced heterogeneity in metal oxidation, an attribute that is discernible even within pure metal phases. − The isolation of individual grains and grain boundaries within a nanodroplet electrochemical cellalso known as scanning electrochemical cell microscopy (SECCM)demonstrated that these grain boundaries exhibit the most substantial electrochemical activity within a polycrystalline metal structure. − The rate of oxidation was shown to be linked with the increase in grain boundary energy, the density of fractured bonds at the grain boundary plane, and the energy of metal oxidation on individual facets. ,,, This discovery presents a significant challenge to conventional methods of interpreting global electrochemical measurements, which have often been premised on the assumption of uniform metal reactivity. − Simultaneously, it is important to note that global reactivity cannot be solely inferred from measurements of isolated nanoscopic areas. This is due to the cooperative interplay between metal heterogeneities resulting from the formation of extensive galvanic couplings, , the diffusive exchange of dissolved species, − among other factors .…”

Structure-dependent CO2 reduction on molybdenite (MoS2) electrocatalysts

“…7,8 To verify and expand on these types of macroscale results, high resolution (nanoscale) electrochemistry has been developed in recent years and tested on a variety of materials to determine the role of these nanostructures in electrocatalytic processes. For example, high-resolution electrochemical mapping with scanning electrochemical cell microscopy (SECCM) 9,10 has indeed confirmed that the EP is highly active, but have also suggested that the BP may not be as inactive as previously thought, with a HER activity comparable to polycrystalline Au or Cu. 11 Such studies have not yet been extended to the study of the eCO 2 RR on MoS 2 and thus, herein, SECCM is deployed to describe the first direct and unambiguous correlation between MoS 2 surface defects and eCO 2 RR activity and (indirectly) selectivity.…”

Recent Developments in Single-Entity Electrochemistry

“…SECCM allows for localized electrochemical measurements by confining the electrochemically active region to the area defined by a meniscus formed between the tip of a nanopipette and a surface of interest . SECCM has been recently used to study diverse reactions at electrode interfaces, such as microscopic defect sites and step edges, grain boundaries, , crystal facets of polycrystalline metal, − defects, , and well-defined topological features. , These features are often challenging to isolate for studies with other SEE methods, such as immobilization on nanoelectrodes (Nanoelectrodes for Single-Entity Electrochemistry) or single-collision electrochemistry (Stochastic Particle Collision Experiments). Additionally, SECCM allows for the direct correlation of intrinsic electrochemical activity with appropriate colocated surface characterization to establish structure–activity relationships …”