In Situ Quantitative Study of Single‐Molecule Photoreduction Activities and Kinetics on 1D–1D Heterostructure

Abstract

Understanding the underlying catalytic mechanisms with nanometer resolution is of critical importance to the rational design of 1D heterogeneous catalysts. However, a fundamental investigation of photocatalytic activities and kinetics at their individual sites is still challenging. Herein, in situ single‐molecule fluorescence microscopy is employed to study the site‐specific catalytic activities and dynamics on 1D–1D heterostructure for the first time. For carbon nanotube (CNT)/CdS nanorod composites, it is found that the CdS end with heterojunction exhibits the highest catalytic conversion rate constant of resazurin photoreduction, which is 30%, 7%, and 19% higher than those of the middle segment and the bare end of CdS, and the CNT end with heterojunction, respectively. A similar trend of adsorption abilities is observed in these structures. Such phenomena can be attributed to the different content of defects in these structures. Regarding the dissociation behaviors, the dissociation rate constants of all structures exhibit an opposite trend to those of adsorption and conversion. The direct and indirect dissociation are found to be predominant on CdS and CNT, respectively. Such investigation provides a deep insight into the understanding of site‐specific properties on 1D heterogeneous catalysts and helps construct the “structure‐dynamics” correlations at the nanoscale.

Single-molecule fluorescence imaging of photocatalytic nanomaterials

“…13g). 202 Upon laser excitation at 488 nm, photoinduced e − generated by CdS facilitated the reduction of Rz to Rf on both CdS and CNT surfaces. Subsequently, Rf molecules were excited by a 532 nm laser for single-molecule fluorescence imaging, by which the kinetic steps including Rz adsorption and conversion as well as Rf dissociation were successfully quantified at various structural features of CNT/CdS (Fig.…”

Heterostructured Photocatalysts for Water Splitting and the Interfacial Charge Transfer

“…A study utilized a fluorescence reaction to observe in realtime the catalytic activity and kinetics of different structural positions on carbon nanotube (CNT)/CdS nanorod composites. 106 Under the laser excitation at 488 nm, CdS-generated photoinduced electrons were capable of reducing resazurin to resorufin on the surface of CdS and CNT. Furthermore, the resulting resorufin molecules could be excited by laser light at 532 nm, as depicted in Figure 16c,d.…”

“…The measured photoelectron transport distance on the CNT reached 16.82 μm, which is the longest distance reported so far. A study utilized a fluorescence reaction to observe in real-time the catalytic activity and kinetics of different structural positions on carbon nanotube (CNT)/CdS nanorod composites . Under the laser excitation at 488 nm, CdS-generated photoinduced electrons were capable of reducing resazurin to resorufin on the surface of CdS and CNT.…”

“…(d) Schematic diagram of the kinetic process including resazurin adsorption, conversion, and resorufin dissociation. Reproduced with permission from ref . Copyright 2024 Wiley.…”