Controllable synthesis of hollow COFs for boosting photocatalytic hydrogen generation

L., Ye,; Xia, Zhihua; Xu, Quanlong; Yang, Yun; Xu, Xiangju; Jin, Huile; Wang, Shun

doi:10.1039/d3cc02914j

Cited by 9 publications

(6 citation statements)

References 35 publications

(42 reference statements)

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“…Additionally, the strong intensity at the baseline of GIWAXS shows a high degree of ordering relative to the SiO 2 /Si substrates with horizontally aligned crystalline structures. Lastly, we completed Raman and XPS analysis on these linkages to confirm the reaction of monomers showing reported spectra agreeing with previous literature. − A more in-depth analysis is available in Figures S17 and S18 in the Supporting Information. This shows that CVD can be used to produce high quality COF films of hydrazone, imine, and β-ketoenamine linkages.…”

Section: Resultsmentioning

confidence: 99%

Solutions Are the Problem: Ordered Two-Dimensional Covalent Organic Framework Films by Chemical Vapor Deposition

Daum,

Ajnsztajn,

Iyengar

et al. 2023

ACS Nano

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Covalent organic frameworks (COFs) are a promising class of crystalline polymer networks that are useful due to their high porosity, versatile functionality, and tunable architecture. Conventional solution-based methods of producing COFs are marred by slow reactions that produce powders that are difficult to process into adaptable form factors for functional applications, and there is a need for facile and fast synthesis techniques for making crystalline and ordered covalent organic framework (COF) thin films. In this work, we report a chemical vapor deposition (CVD) approach utilizing co-evaporation of two monomers onto a heated substrate to produce highly crystalline, defect-free COF films and coatings with hydrazone, imine, and ketoenamine COF linkages. This all-in-one synthesis technique produces highly crystalline, 40 nm–1 μm-thick COF films on Si/SiO2 substrates in less than 30 min. Crystallinity and alignment were proven by using a combination of grazing-incidence wide-angle X-ray scattering (GIWAXS) and transmission electron microscopy (TEM), and successful conversion of the monomers to produce the target COF was supported by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and UV–vis measurements. Additionally, we used atomic force microscopy (AFM) to investigate the growth mechanisms of these films, showing the coalescence of triangular crystallites into a smooth film. To show the wide applicability and scope of the CVD process, we also prepared crystalline ordered COF films with imine and ketoenamine linkages. These films show potential as high-quality size exclusion membranes, catalytic platforms, and organic transistors.

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Section: Resultsmentioning

confidence: 99%

Solutions Are the Problem: Ordered Two-Dimensional Covalent Organic Framework Films by Chemical Vapor Deposition

Daum,

Ajnsztajn,

Iyengar

et al. 2023

ACS Nano

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“…It is generally acknowledged that the morphology of a photocatalyst greatly influences its surface property, optical absorption, and charge-carrier diffusion, etc. ,, In this regard, innovative approaches for better control of the morphology of COFs toward ideal structural, electronic, and photocatalytic alterations are key. Very recently, a cubic hollow COF was prepared with NaCl as a hard template (denoted as COF-LZU1-X, Figure ).…”

Section: Strategies For Improving the Photoactivity Of Cofsmentioning

confidence: 99%

“…Very recently, a cubic hollow COF was prepared with NaCl as a hard template (denoted as COF-LZU1-X, Figure ). Compared with the pristine COF-LZU1, COF-LZU1-600 possessed an improved light harvesting capability, reduced charge-carrier diffusion distance, and boosted H 2 evolution photoactivity. In addition, Bai and co-workers synthesized an anthraquinone functionalized COF (denoted as AQ-COF) linked by β-ketoenamines with a noodle-like nanofiber morphology .…”

Section: Strategies For Improving the Photoactivity Of Cofsmentioning

confidence: 99%

Progress of Covalent Organic Framework Photocatalysts: From Crystallinity–Stability Dilemma to Photocatalytic Performance Improvement

Ran,

Xu,

Yang

et al. 2024

ACS Catal.

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Covalent organic frameworks (COFs) are a category of organic crystalline porous materials, which have been identified as an appealing and promising photocatalyst owing to attractive characteristics such as molecular structure designability, extended πconjugation, rich porosity, and high surface area. In the past decade, research on COFs has been blossoming and currently represents one of the most prospective forefronts in heterogeneous photocatalysis. This review summarizes the latest advances in the synthesis, characterization, and properties of COF-based photocatalysts, with emphasis on the state-ofthe-art strategies to tackle the crystallinity−stability dichotomy of COFs, in particular, by means of the conversion of the linkages and the control of the interlayer interactions. In addition, an arsenal of approaches for enhancing the photocatalytic performance of COFs are discussed in detail, such as boosting exciton dissociation, improving crystallinity, regulating molecular structure, doping, loading cocatalyst, coupling sensitizer, constructing heterojunction, and modulating morphology. Finally, this review concludes with opportunities, challenges, and perspectives for the further cutting-edge development of COF-based photocatalysts.

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“…In the recent literature, there have been reports on the rational design of COF nanomaterials with precise crystalline forms and consistent pore size distributions, aiming to enhance their characteristics and expand their potential uses . The enhancement of π-stacking interactions between layers of COFs and the manipulation of the stiffness or flexibility of the constituent monomers will have an impact on the crystalline structure of the resulting COFs. , Various kinds of well-defined crystallites, such as fabric fibers, belts, cubes, sheets, platelets, and spheres, are being created effectively for COFs. − Nevertheless, the occurrence of all-in-one COF microflowers possessing prospective characteristics has been scarcely documented in the literature.…”

Section: Introductionmentioning

confidence: 99%

Heterosporous Phenylpyridine-Based Covalent Organic Framework Microflowers for Highly Selective Sensing of Hydrogen Sulfide

Chen,

EL-Mahdy

2024

ACS Appl. Polym. Mater.

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Covalent organic frameworks (COFs) demonstrate considerable promise for gas and chemical sensing applications. Although there has been notable advancement in synthesizing such crystalline materials, the utilization of template-free approaches to fabricate COFs with flower-like microstructures remains infrequent. Herein, we report the synthesis of microflower-like and hollow microtubular phenylpyridine-based COFs� TAPP-TFBZ and TAPP-TFBP COFs�through template-free [4 + 4] polycondensation of 5′-(2,6-bis(4-aminophenyl)pyridin-4-yl)-[1,1′:3′,1″-terphenyl]-4,4″-diamine (TAPP-4NH 2 ) with 4′,5′-bis(4-formylphenyl)-[1,1′:2′,1″-terphenyl]-4,4″-dicarbaldehyde (TFBZ-4CHO) and 5′,5″-bis(4-formylphenyl)-[1,1′:3′,1″:3″,1‴-quaterphenyl]-4,4‴-dicarbaldehyde (TFBP-4CHO), respectively. The resultant COFs exhibit exceptional thermal stability beyond 592 °C and possess high Brunauer−Emmett−Teller (BET) surface areas surpassing 943 m 2 g −1 . The TAPP-TFBZ COF has a dual porosity feature, whereas the TAPP-TFBP COF demonstrates a singular porosity. Interestingly, the TAPP-TFBZ COF microflowers have promising capabilities as a prospective fluorescent chemosensor, enabling the sensitive and selective sensing of H 2 S. Our developed sensing assay demonstrates a time efficiency of 10 min for completion while achieving a limit of detection of 1.6 nM. This work will advance research into the design concepts of flower-shaped COF materials that hold potential for applications in gas and chemical sensing.

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Controllable synthesis of hollow COFs for boosting photocatalytic hydrogen generation

Abstract: COF-LZU1 with cubic hollow structure was fabricated through a hard template approach by using water solvable NaCl as template. The precisely prepared COF-LZU1 hollow cube displays enhanced H2 evolution rate...

Cited by 9 publications

References 35 publications

Solutions Are the Problem: Ordered Two-Dimensional Covalent Organic Framework Films by Chemical Vapor Deposition

Solutions Are the Problem: Ordered Two-Dimensional Covalent Organic Framework Films by Chemical Vapor Deposition

Progress of Covalent Organic Framework Photocatalysts: From Crystallinity–Stability Dilemma to Photocatalytic Performance Improvement

Heterosporous Phenylpyridine-Based Covalent Organic Framework Microflowers for Highly Selective Sensing of Hydrogen Sulfide

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