This research is from Angew. Chem. Int. Ed. 2022, 61(19), e202201900 completed by Professor Long Chen and co-workers.

Abstract Paraphrase
1) The article addresses key challenges in solar steam generation (SSG) posed by the hydrophobic nature and limited near-infrared (NIR) light absorption of porous organic polymers. The authors introduce a novel 1,4,5,8-tetrakis(phenylamino)anthracene-9,10-dione (TPAD)-based covalent organic framework (COF), TPAD-COF, which is superhydrophilic and absorbs light broadly from the UV/Vis to NIR regions.
2) TPAD-COF is presented as an efficient photothermal conversion material that, even without additives, achieves a water evaporation rate of 1.42 kg m−2 h−1 and an energy conversion efficiency of 94% under one sun irradiation.
3) The material's light absorption range is further extended through post-synthetic modification by chelating BF2 moieties, although this results in a decrease in hydrophilicity. Notably, the hydrophilicity of TPAD-COF is identified as more critical for SSG performance than light absorption efficiency.

Background Summary
1) Industry Problems: The escalating demand for clean water and the limitations of existing desalination and water purification technologies highlight the need for efficient SSG methods. The hydrophobicity and insufficient light absorption of photothermal conversion materials are significant hurdles.
2) Previous Solutions: Researchers have explored various materials, including carbon-based materials and metallic nanoparticles, and attempted to enhance their properties through post-treatments such as carbonization and chemical hydrophilic treatment.
3) Innovations: The authors propose a TPAD-based COF that combines superhydrophilicity and broad light absorption. This material is synthesized without the need for post-treatments, offering a streamlined and high-performance solution for SSG.

Experimental Details
1) Synthesis of Monomers: TPAD-DMO and TPAD-NH2 were synthesized via Buchwald–Hartwig amination and characterized using NMR and MS, with TPAD-DMO's structure confirmed by single-crystal X-ray diffraction.
2) Fabrication of TPAD-COF: TPAD-COF was produced through poly-condensation under solvothermal conditions and characterized using FT-IR, CP-MAS NMR, SEM, and TEM, revealing a rod-like morphology.
3) Post-Synthetic Modification: TPAD-COF-BF2 was synthesized by incorporating BF2 moieties, resulting in a larger π-conjugated core structure that was characterized using similar techniques, showing a similar morphology but altered hydrophilicity.

Characteristic Test and Analysis
1) Characterization Techniques: PXRD confirmed the crystallinity of TPAD-COFs, with Pawley refinement providing cell parameters. N2 adsorption-desorption measurements revealed microporosity and surface areas of 1170 m2 g−1 for TPAD-COF and 531 m2 g−1 for TPAD-COF-BF2.
2) Thermal and Chemical Stability: TGA showed TPAD-COF maintained 95% of its initial weight up to 450 °C, indicating high thermal stability. Chemical stability was demonstrated after treatment in harsh conditions.
3) SSG Performance: TPAD-COF exhibited a high evaporation rate and energy conversion efficiency, superior to most hybrid materials and charcoal-treated POPs. In contrast, TPAD-COF-BF2, despite higher light absorption efficiency, showed lower performance due to reduced hydrophilicity.

Conclusion
1) The developed TPAD-COF is an efficient photothermal conversion material for SSG, achieving high water evaporation rates and energy conversion efficiencies, surpassing many existing materials.
2) The study underscores the critical role of hydrophilicity in SSG performance, even more so than light absorption efficiency.
The work opens a new pathway for creating efficient COF-based photothermal conversion materials for SSG by integrating NIR dyes, offering a promising direction for material development.
3) It is recommended that the authors investigate the material's performance under various environmental conditions and its potential for integration into existing water treatment infrastructure. Additionally, exploring the recyclability and long-term stability of TPAD-COF in practical SSG applications would be valuable.


Superhydrophilic 2D Covalent Organic Frameworks as Broadband Absorbers for Efficient Solar Steam Generation
Authors: Xiaoli Yan, Shanzhi Lyu, Xiao-Qi Xu, Dr. Weiben Chen, Pengna Shang, Zongfan Yang, Guang Zhang, Prof. Weihua Chen, Prof. Yapei Wang, Prof. Long Chen
DOI: 10.1002/anie.202201900
Original Link：https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202201900