Volcano-Type Behavior in Spatially Resolved Electron Transfer and Hydrogen Evolution Reaction Mapping over 2D...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Developing efficient electrochemical devices requires understanding interfacial electron transfer dynamics.
• Two-dimensional (2D) materials are promising catalysts, but their nanoscale electrochemical properties, especially layer-by-layer, are understudied.
• High-resolution mapping of electron transfer is key to advancing 2D material catalysis.

Purpose of the Study:

• To spatially resolve and quantify interfacial electron transfer at the 2D semiconducting WSe2 electrode-electrolyte interface.
• To investigate the layer-dependent electrochemical activity of WSe2.
• To elucidate the relationship between electronic structure, charge transport, and catalytic performance in WSe2.

Main Methods:

• In situ electron transfer mapping at the WSe2 electrode-electrolyte interface.
• High-resolution spatial resolution and quantification of outer-sphere and inner-sphere electron transfer.
• Micro-electrochemical hydrogen evolution reaction (HER) measurements.

Main Results:

• Spatially resolved electron transfer dynamics were successfully mapped at the WSe2 interface.
• WSe2 demonstrated a volcano-type behavior in electrochemical activity, with peak performance at four layers.
• The observed phenomenon is attributed to the interplay of layer-specific electronic density of states and interlayer charge carrier tunneling.

Conclusions:

• The study provides critical nanoscale insights into the electrochemical activity of 2D WSe2.
• Layer thickness significantly influences the catalytic performance of WSe2, with an optimal four-layer structure identified.
• Understanding these layer-dependent electronic and transport properties is crucial for designing next-generation 2D material-based electrochemical devices.