Defect-rich two-dimensional (2D) layered materials have been the most promising candidate catalysts that can replace noble metals in catalysis. Nevertheless, the fabrication of defect-rich 2D layered material catalysts is still at the stage of trial-and-error so far. The insightful comprehension of catalytic dynamics at structural defects of 2D layered material is crucial for rational design of high-performance catalysts via defect engineering. Here, we unveiled the heterogeneous photocatalytic dynamics in defects of 2D layered InSe in situ by single-molecule imaging. From the super-resolved mapping results, we visualized and distinguished the photocatalytic activity at individual structural features on 2D layered InSe and found that vacancy has the highest photocatalytic activity among four structural features (i.e., basal plane, edge, wrinkle, and vacancy). We further deconvoluted the individual dynamic steps and analyzed quantitatively to extract the key dynamic parameters. Specifically, we discovered that the highest photocatalytic activity of vacancy was mainly due to the highest chemical conversion rate. However, surprisingly, it possessed the lowest reactant adsorption strength, slowest product dissociation rate, and smallest product surface diffusion coefficient. Whereas, other defects, such as edge and wrinkle, presented much higher reactant adsorption strength, product dissociation rate, and product surface diffusion coefficient, but lower chemical conversion rate. These special behaviors in dynamic photocatalytic properties of defects were correlated to their differences in electronic energy levels. Furthermore, we revealed that surface diffusion behaviors and layer number of bulk materials could also significantly affect the photocatalytic dynamics in the defects of layered InSe. This work paves the way for establishing the in-depth correlation between catalytic dynamics and physicochemical properties of defects.

Single-molecule photocatalytic dynamics at defects of layered two-dimensional InSe

ACS Spring Meeting 2021

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