Luo Laiyu, Wu Qinglong, Wang Siyu, Song Haojie, Li Jiaqi, Zhang Liping, Zhang Qun, Fang Yuanxing, Jiang Baojiang, Wang Xinchen
Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People's Republic of China, Heilongjiang University, Harbin, 150080, P.R. China.
Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, P.R. China.
Angew Chem Int Ed Engl. 2025 Jul;64(29):e202507415. doi: 10.1002/anie.202507415. Epub 2025 May 24.
Poly(heptazine imide) (PHI) is a promising photocatalyst for hydrogen peroxide (HO) production; however, enhancing its specific surface area to expose internal active sites and understanding their roles in key mechanistic steps for the HO synthesis remain challenging. Here, we utilized organic cations to exfoliate bulk PHI and fabricate PHI nanosheets for producing HO at a rate of 27.35 mmol g h under simulated solar light irradiation, outperforming most of the reported carbon nitride-based catalysts. Importantly, after 36 h of cyclic accumulation reactions in a self-created spiral flow reactor, the HO concentration stabilized at 2.7 wt.%, close to medical sterilization levels. In situ spectroscopic characterizations and density functional theory calculations revealed that the exfoliation results in molecular reconfiguration of the PHI basal planes, forming the active sites to promote charge separation and electron localization. This new structure also creates midgap states, enabling direct HO production via a one-step, two-electron pathway, bypassing the superoxide radical pathway. Theoretical calculations suggest that the localized electronic structure created by the active sites favors the protonation of adsorbed O and stabilizes the *OOH species, which converts to HO. This study elucidates and underscores the importance of active-site reconfiguration for efficient photocatalytic oxygen reduction reaction (ORR) pathways.
聚（七嗪酰亚胺）（PHI）是一种很有前景的用于生产过氧化氢（HO）的光催化剂；然而，提高其比表面积以暴露内部活性位点并了解它们在HO合成关键机制步骤中的作用仍然具有挑战性。在此，我们利用有机阳离子剥离块状PHI并制备PHI纳米片，以在模拟太阳光照射下以27.35 mmol g h的速率生产HO，性能优于大多数已报道的基于氮化碳的催化剂。重要的是，在自建的螺旋流反应器中进行36小时的循环累积反应后，HO浓度稳定在2.7 wt.%，接近医疗消毒水平。原位光谱表征和密度泛函理论计算表明，剥离导致PHI基面的分子重排，形成促进电荷分离和电子定位的活性位点。这种新结构还产生了带隙中间态，能够通过一步两电子途径直接生产HO，绕过超氧自由基途径。理论计算表明，由活性位点产生的局域电子结构有利于吸附的O的质子化并稳定*OOH物种，后者转化为HO。这项研究阐明并强调了活性位点重排对于高效光催化氧还原反应（ORR）途径的重要性。
