Imaging and Quantifying the Formation of Single Nanobubbles at Single Platinum Nanoparticles during the Hydrogen Evolution Reaction

While numerous efforts have been made toward the design of sustainable and efficient nanocatalysts of the hydrogen evolution reaction, there is a need for the operando observation and quantification of the formation of gas nanobubbles (NBs) involved in this electrochemical reaction. It is achieved herein through interference reflection microscopy coupled to electrochemistry and optical modeling. In addition to analyzing the geometry and growth rate of individual NBs at single nanocatalysts, the toolbox offered by superlocalization and quantitative label-free optical microscopy allows analyzing the geometry (contact angle and footprint with surface) of individual NBs and their growth rate. It turns out that, after a few seconds, NBs are steadily growing while they are fully covering the Pt nanoparticles that allowed their nucleation and their pinning on the electrode surface. It then raises relevant questions related to gas evolution catalysts, such as, for example, does the evaluation of NB growth at the single nanocatalyst really reflect its electrochemical activity?

Automated summary

Efforts have been made towards designing sustainable and efficient nanocatalysts for the hydrogen evolution reaction, but there is a need for the real-time observation and quantification of gas nanobubble formation. This study utilized interference reflection microscopy coupled with electrochemistry and optical modeling to analyze individual nanobubbles' geometry and growth rate. The results showed that nanobubbles cover Pt nanoparticles and steadily grow on the electrode surface, raising questions about the relationship between nanobubble growth and electrochemical activity.