Designed\nSynthesis\nof Mesoporous sp<sup>2</sup> Carbon-Conjugated\nBenzothiadiazole Covalent Organic Frameworks for Artificial Photosynthesis\nof Hydrogen Peroxide

Artificial photosynthesis of hydrogen\nperoxide (H<sub>2</sub>O<sub>2</sub>) from ambient air, water, and\nsunlight has\nattracted considerable\nattention recently. Despite being extremely challenging to synthesis,\nsp<sup>2</sup> carbon-conjugated covalent organic frameworks (COFs)\ncan be powerful and efficient materials for the photosynthesis of\nH<sub>2</sub>O<sub>2</sub> due to desirable properties. Herein, we\nreport the designed synthesis of an sp<sup>2</sup> carbon-conjugated\nCOF, BTD-sp<sup>2</sup>c-COF, from benzothiadiazole and triazine units\nwith high crystallinity and ultralarge mesopores (∼4 nm). The\nsp<sup>2</sup> carbon-conjugated skeletons guarantee BTD-sp<sup>2</sup>c-COF superior optoelectronic properties and chemical stability.\nBTD-sp<sup>2</sup>c-COF exhibits an exceptional efficiency of 3066\nμmol g<sup>–1</sup> h<sup>–1</sup> from pure water\nand air, much better than that of BTD-imine-COF. In contrast, the\nresilience of BTD-imine-COF is compromised due to the participation\nof imine linkages in the oxygen reduction reaction. Importantly, in\nsitu characterization and theoretical calculation results reveal that\nboth benzothiadiazole and triazine units serve as oxygen reduction\nreaction centers for H<sub>2</sub>O<sub>2</sub> photosynthesis through\na sequential electron transfer pathway, while the vinylene bridged\nphenyls serve as water oxidation reaction centers. The sp<sup>2</sup> carbon-conjugated COFs pave the way for potent artificial photosynthesis.