Nanoscale quantification and structure–dynamics correlation of photoredox reactions on 2D nanoplates via single-molecule localization microscopy

Abstract

Understanding the site-specific photoredox behavior of anisotropic 2D photocatalysts remains a significant challenge using conventional techniques. Here, we employ single-molecule localization microscopy (SMLM) to quantitatively map and deconvolute nanoscale photoredox kinetics on BiOBr nanoplates with dominant (001) and (010) crystal planes-designated as BiOBr-001 and BiOBr-010, respectively. The rate constants for adsorption, catalytic conversion, and dissociation are quantified on BiOBr with nanometer precision (∼24 nm). A strong correlation between photoredox reactions is observed on nanoscale boundary subregions of BiOBr, as revealed by Spearman's coefficients. This is probably due to incomplete crystal termination with surface defects at corners and edges, which enhance charge separation and catalytic efficiency. In addition, BiOBr-001 and BiOBr-010 exhibit distinct adsorption and dissociation behaviors due to morphological and structural differences. The terminal oxygen atoms with negative charges on BiOBr-001 BPs repel anionic substrates, reducing their adsorption rates. In contrast, BiOBr-010 possesses an open-channel structure with abundant active sites, which facilitate substance adsorption and inhibit product dissociation. Within a single nanoplate, heterogeneous kinetic properties are also observed due to the presence of high-index facets, structural defects and steric hindrance. Therefore, our work sheds light on single-molecule studies of photoredox kinetics on 2D materials, establishing structure-dynamics correlations at the nanoscale.