COF-Based Photocatalysts for Enhanced Synthesis of Hydrogen Peroxide

Abstract

Covalent Organic Frameworks (COFs), with their intrinsic structural regularity and modifiable chemical functionality, have burgeoned as a pivotal material in the realm of photocatalytic hydrogen peroxide (H₂O₂) synthesis. This article reviews the recent advancements and multifaceted approaches employed in using the unique properties of COFs for high-efficient photocatalytic H₂O₂ production. We first introduced COFs and their advantages in the photocatalytic synthesis of H₂O₂. Subsequently, we spotlight the principles and evaluation of photocatalytic H₂O₂ generation, followed by various strategies for the incorporation of active sites aiming to optimize the separation and transfer of photoinduced charge carriers. Finally, we explore the challenges and future prospects, emphasizing the necessity for a deeper mechanistic understanding and the development of scalable and economically viable COF-based photocatalysts for sustainable H₂O₂ production.

Keywords: H2O2 photosynthesis; covalent organic framework; photosynthesis; solar conversion.

Figure 1

The advantages of COFs for the photosynthesis of H₂O₂.

Figure 2

(a) Schematic illustration and (b) Corresponding energy diagrams of the oxygen reduction and water oxidation involved in H₂O₂ photosynthesis. Reproduced with permission [1].

Figure 3

(a) Synthetic process of sulfone-modified COFs. (b) Photocatalytic H₂O₂ production rate of C-COFs (black), S-COFs (red), and FS-COFs (blue). (c) UV/Vis spectrum of FS-COFs and AQY for H₂O₂ production. Reproduced with permission [113]. Copyright 2023, Wiley-VCH.

Figure 4

(a) Synthetic route of thiourea-functionalized COFs. (b) Relative OH bending intensity of thiourea-functionalized COFs. (c) H₂O₂ generation rate. (d) Weight differential index of fragments in excited states 4–9 of Bpt-CTF. (e) Schematic diagram of the catalytic pathway. Reproduced with permission [114]. Copyright 2022, Wiley-VCH.

Figure 5

(a) Schematic diagram of the synthesis process. (b) H₂O₂ production yield. (c) H₂O₂ production rate. (d) AQY of TpDz at chosen wavelengths: 420 (purple), 450 (light blue), 500 (green), and 600 (red) nm. Reproduced with permission. Copyright 2023 [104], Wiley-VCH.

Figure 6

(a) Synthetic process of fluorinated COFs. (b) N2 sorption isotherms of obtained COFs. (c) Specific surface areas and pore volumes in H-COF, TF-COF, and TF50-COF Using BET and Langmuir Models. (d) Crystal stacking energies of TF-COF and H-COF. (e) Photocatalytic H₂O₂ production rate for 1 h. (f) Photocatalytic H₂O₂ production rate for 5 h. (g) The SCC efficiencies of synthesized COFs. Reproduced with permission [107]. Copyright 2022, Wiley-VCH.

Figure 7

(a) Synthetic route of BTEA-COF (red) and EBA-COF (blue). (b) UV-DRS of EBA-COF (blue) and BTEA-COF (red). (c) Mott-Schottky plot of the BTEA-COF. (d) Reactions of EBA-COF under varied gas atmospheres. (e) Photocatalytic production of H₂O₂ using EBA-COF in the presence of KI, CuSO₄, and p-benzoquinone. Reproduced with permission [115]. Copyright 2022, American Chemical Society.