A thioether-functionalized pyrene-based covalent organic framework anchoring ultrafine Au nanoparticles for efficient photocatalytic hydrogen generation

Covalent organic frameworks (COFs) have lately emerged as a blooming class of potential materials for photocatalytic water splitting because of their high crystallinity, huge surface areas, and struc-tural versatility. However, the photocatalytic performance for most pure COFs face some limitations factors, such as the significant recombination of photogenerated carriers and slow charge transfer. Herein, a novel thioether-functionalized pyrene-based COF (S4-COF) was effectively produced and chosen as a support for the immobilization of ultrafine gold nanoparticles (Au NPs). S4-COF photo -catalyst with Au as cocatalyst demonstrates remarkable photocatalytic activity with a H2 generation rate of 1377 limol g-1 h-1 under visible light (>420 nm), which is ca. 4.5-fold increase comparing to that of pure S4-COF (302 limol g-1 h-1). Au NPs anchored on S4-COF possess an ultrafine size distri-bution ranging from 1.75 to 6.25 nm with an average size centered at 3.8 nm, which benefits from the coordination interaction between thioether groups and Au. Meanwhile, the produced Au@S4-COF can generate a stable photocatalytic H2 generation during the four recycles and pre-serve its crystallinity structure after the stability testing. The Au NPs anchored on the S4-COF pho-tocatalyst can greatly accelerate the separation of photogenerated carriers and increase charge transfer because of the combined function of Au NPs and thioether groups. Such a method can not only prevent the aggregation of Au NPs onto thioether-containing COFs to achieve long-term photo -stability but also allow uniform dispersion for an ordered structure of photocatalysts. This work provides a rational strategy for designing and preparing COF-based photocatalysts for solar-driven H2 production.(c) 2022, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

This article presents a novel thioether-functionalized pyrene-based COF catalyst with ultrafine gold nanoparticles (Au NPs) as a cocatalyst, exhibiting remarkable photocatalytic activity and increased H2 generation rate under visible light.