Xuehui Li

Covalent organic framework (COF)‐based catalysts are promising for overall photocatalytic hydrogen peroxide (H ₂ O ₂ ) production, yet the sluggish kinetics of water oxidation reaction (WOR) and inefficient charge carrier processes limit the catalytic performance. Herein, by modulating the donor structure of COF where the WORs take place, we designed and synthesized a new benzothiophene‐based donor moiety (BTPC) with intramolecular windmill‐type π ‐extension to simultaneously enrich WOR active sites and enhance charge carrier separation. The BTPC‐based COFs exhibited remarkably enhanced photocatalytic H ₂ O ₂ production performance compared with the conventional benzotrithiophene‐based COF (BTT‐TAT). Notably, BTPC‐TAT achieved a rate of 9.08 mmol g ⁻¹ h ⁻¹ , which is over 3‐fold higher than that of BTT‐TAT (2.94 mmol g ⁻¹ h ⁻¹ ). In the following continuous‐flow H ₂ O ₂ generation system, the immobilized BTPC‐TAT also exhibited excellent stability and facile operation for in situ H ₂ O ₂ generation coupled with Rhodamine B degradation. Comprehensive studies demonstrate that the “windmill‐type π ‐extension” strategy in the donor moiety promotes charge carrier separation and prolongs carrier lifetime, while enhancing WOR interfacial interactions via improved water adsorption and reduced energy barriers for intermediate formation. This work introduces a new donor moiety for efficient photocatalytic H ₂ O ₂ production and provides insights into rational intra‐donor π ‐system engineering.

Covalent organic framework (COF)‐based catalysts are promising for overall photocatalytic hydrogen peroxide (H ₂ O ₂ ) production, yet the sluggish kinetics of water oxidation reaction (WOR) and inefficient charge carrier processes limit the catalytic performance. Herein, by modulating the donor structure of COF where the WORs take place, we designed and synthesized a new benzothiophene‐based donor moiety (BTPC) with intramolecular windmill‐type π ‐extension to simultaneously enrich WOR active sites and enhance charge carrier separation. The BTPC‐based COFs exhibited remarkably enhanced photocatalytic H ₂ O ₂ production performance compared with the conventional benzotrithiophene‐based COF (BTT‐TAT). Notably, BTPC‐TAT achieved a rate of 9.08 mmol g ⁻¹ h ⁻¹ , which is over 3‐fold higher than that of BTT‐TAT (2.94 mmol g ⁻¹ h ⁻¹ ). In the following continuous‐flow H ₂ O ₂ generation system, the immobilized BTPC‐TAT also exhibited excellent stability and facile operation for in situ H ₂ O ₂ generation coupled with Rhodamine B degradation. Comprehensive studies demonstrate that the “windmill‐type π ‐extension” strategy in the donor moiety promotes charge carrier separation and prolongs carrier lifetime, while enhancing WOR interfacial interactions via improved water adsorption and reduced energy barriers for intermediate formation. This work introduces a new donor moiety for efficient photocatalytic H ₂ O ₂ production and provides insights into rational intra‐donor π ‐system engineering.

Covalent organic frameworks (COFs) are promising for photocatalytic H₂O₂ generation. However, imine‐linked COFs often suffer from poor charge separation and low photocatalytic performance. Therefore, constructing sp² carbon‐linked COFs with extended π‐conjugation is very significant in boosting the photocatalytic properties, but their synthesis is challenging due to the low reversibility of C═C bond. Here, two vinylene‐linked COFs: BBT‐ACN COF‐1 and BBT‐ACN COF‐2 are designed. To investigate the effects of different structures on exciton binding energy (E_b), the designed BBT‐ACN COF‐1 possesses a Donor–Acceptor (D–A) structure with the electron‐deficient benzobisthiazole (BBT) as acceptor and benzotrithiophene as donor, while the latter holds a π‐A structure with pyrene as π‐unit and BBT as acceptor. Both BBT‐ACN COFs show photocatalytic H₂O₂ production activity in a two‐step 2e⁻ oxygen reduction reaction (ORR). As anticipated, the D–A structured BBT‐ACN COF‐1 exhibits a lower E_b value, and its photocatalytic H₂O₂ production rate in pure water and air reaches up to 2.50 mmol g⁻¹ h⁻¹, ≈3 times higher than that of the π‐A structured BBT‐ACN COF‐2 (0.91 mmol g⁻¹ h⁻¹). This study reveals that constructing fully sp²‐carbon‐linked COFs is very beneficial for photocatalytic H₂O₂ production, which provides an effective approach for designing high‐performance organic photocatalysts.

A novel impregnation-deposition method was applied to prepare presulfided MoS₂/Al₂O₃ catalysts with large surface areas for the application of hydrodesulfurization (HDS). The synthesized catalysts were characterized systematically, and their catalytic performances were evaluated by the HDS of dibenzothiophene (DBT). It is found that the impregnation-deposition method improves the surface area of the synthesized catalysts by eliminating the micropores of the alumina support and adding mesostructured MoS₂ particles within the support. Moreover, this method enhances the reducibility of the sulfided Mo species, as characterized by temperature-programed reduction (TPR) and X-ray photoelectron spectroscopy. Compared to the impregnation method, the impregnation-deposition method leads to the formation of more active sites as proved by TPR and CO-Fourier-transform infrared analyses. Hence, the reaction conversion rates and the hydrogenation/direct-desulfurization ratios of the DBT on the catalysts synthesized by the impregnation-deposition method are 1.3 times and 1.5 times as high as those of the catalysts made by the conventional impregnation method, respectively.