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| 1 | Two-dimensional conjugated N-rich covalent organic frameworks for superior sodium storage显示文摘Sodium-ion batteries(SIBs) are considered as a promising next-generation energy storage system. To achieve the large-scale application of SIBs, it is crucial to develop cost-effective anode materials with high Na-ion storage capacity. Herein twodimensional(2D) conjugated covalent organic frameworks(c COFs) with N-rich phthalocyanine(Pc) units fused via benzene moieties(named MPc-2D-c COFs) were explored as the SIBs anode materials. Electrochemical tests reveal their high reversible capacities of 538 and 342 m A h g^(-1) at 50 and 1000 m A g^(-1), respectively, good rate performance, and excellent stability,comparable to the state-of-the-art anode materials of SIBs, indicating their outstanding Na-ion storage performance. Ex situ Xray photoelectron and Fourier transform infrared spectroscopies together with theoretical calculations disclose the N atoms at the pore channels and conjugated pyrrole moieties of MPc-2D-c COFs provide abundant Na-ion storage sites. This, in cooperation with the enhanced electrical conductivity owing to the 2D conjugated structure, contributes to the outstanding Na-ion storage capacity of MPc-2D-c COFs. The present result is surely helpful for developing high-performance and cost-effective COFs as electroactive materials for SIBs. | Xiya Yang Yucheng Jin Baoqiu Yu Lei Gong Wenbo Liu Xiaolin Liu Xin Chen Kang Wang Jianzhuang Jiang | 2022 | Science China Chemistry2022，65，7： | 0 |
| 2 | Hydrothermal synthesis of polyimide-linked covalent organic frameworks towards ultrafast and stable cathodic sodium storage显示文摘Redox-active organic materials are capturing growing attention as cathode materials for sustainable alkaline metal ion batteries.However,the storage of Na+in most organic materials-based cathodes is plagued by low capacity and unsatisfying rate performance due to their low active site densities and limited exposed active sites.Herein,two polyimide-linked covalent organic frameworks(COFs),namely HATN-PD-COF and HATN-TAB-COF,were fabricated from hydrothermal synthesis with redoxactive triphenylene-2,3,6,7,10,11-hexacarboxylic acid and aromatic amines as starting materials.Powder X-ray diffraction and electron microscopy analysis indicate the high crystalline nature of these COFs with AA stacking configuration and orderly mesoporous tunnel.N_(2) sorption measurement discloses the permanent porosity of these two COFs with a Brunauer-EmmettTeller surface area of 1,065-1,200 m^(2)g^(-1)and a large pore size of 2.0-3.1 nm.Galvanostatic intermittent titration technique and density functional theory calculations reveal the facile Na+ion diffusion along the mesoporous tunnel of these COFs with a small energy barrier of 0.13-0.40 e V.In particular,the as-prepared COFs based-cathodes show ultrafast and stable Na+storage associated with their conjugated electronic structure,highly ordered mesoporous tunnel,robust structure,and redox-active C=N/C=O-rich framework as exemplified by the high reversible capacity of 210 m A h g^(-1)at 200 m A g^(-1),record-high rate performance(195 m A h g^(-1)at a high current density of 10,000 m A g^(-1))among organic electrodes and the capacity retention of nearly 91%at 10,000 m A g^(-1)after 7,000 cycles for HATN-PD-COF. | Xiya Yang Lei Gong Zhixin Liu Qianjun Zhi Baoqiu Yu Xin Chen Kang Wang Xiaofeng Li Dongdong Qi Jianzhuang Jiang | 2024 | Science China Chemistry2024，67，4： | 0 |
| 3 | Covalent organic frameworks with imine proton acceptors for efficient photocatalytic H_(2) production显示文摘Covalent organic frameworks (COFs) are promising crystalline materials for the light-driven hydrogen evolution reaction (HER) due to their tunable chemical structures and energy band gaps.However,deeply understanding corresponding mechanism is still challenging due to the multiple components and complicated electron transfer and reduction paths involved in photocatalytic HER.Here,the photocatalytic HER investigation has been reported based on three COFs catalysts,1–3,which are prepared by benzo[1,2-b:3,4-b’:5,6-b’]trithiophene-2,5,8-trialdehyde to react with C3symmetric triamines including tris(4-aminophenyl)amine,1,3,5-tris(4-aminophenyl)benzene,and (1,3,5-tris-(4-aminophenyl)triazine,respectively.As the isostructural hexagonal honeycomb-type COF of 2 and 3 reported previously,the crystal structure of 1 has been carefully correlated through the powder X-ray diffraction study with the help of theoretical simulations.1 shows highly porous framework with Brunauer-Emmett-Teller surface area of1249 m^(2)/g.Moreover,the introduction of ascorbic acid into the photocatalytic system of COFs achieves the hydrogen evolution rate of 3.75,12.16 and 20.2 mmol g^(–1)h^(–1) for 1–3,respectively.The important role of ascorbic acid in photocatalysis of HER is disclosed to protonate the imine linkages of these COFs,leading to the obvious absorbance red-shift and the improved charge separation efficiency together with reduced resistance in contrast to pristine materials according to the spectroscopic and electronic characterizations.These innovations of chemical and physical properties for these COFs are responsible for their excellent photocatalytic performance.These results elucidate that tiny modifications of COFs structures is able to greatly tune their band structures as well as catalytic properties,therefore providing an available approach for optimizing COFs functionalities. | Xiaolin Liu Xiya Yang Xu Ding Hailong Wang Wei Cao Yucheng Jin Baoqiu Yu Jianzhuang Jiang | 2023 | Chinese Chemical Letters2023，34，10： | 0 |
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