Plasmonic imaging of the layer-dependent electrocatalytic activity of two-dimensional catalysts.

Studying the localized electrocatalytic activity of heterogeneous electrocatalysts is crucial for understanding electrocatalytic reactions and further improving their performance. However, correlating the electrocatalytic activity with the microscopic structure of two-dimensional (2D) electrocatalysts remains a great challenge due to the lack of in situ imaging techniques and methods of tuning structures with atomic precision. Here, we present a general method of probing the layer-dependent electrocatalytic activity of 2D materials in situ using a plasmonic imaging technique. Unlike the existing methods, this approach was used to visualize the surface charge density and electrocatalytic activity of single 2D MoS2 nanosheets, enabling the correlation of layer-dependent electrocatalytic activity with the surface charge density of single MoS2 nanosheets. This work provides insights into the electrocatalytic mechanisms of 2D transition metal dichalcogenides, and our approach can serve as a promising platform for investigating electrocatalytic reactions at the heterogeneous interface, thus guiding the rational design of high-performance electrocatalysts.