Constructing photocatalytically active and stable covalent organic frameworks containing both oxidative and reductive reaction centers remain a challenge. In this study, benzotrithiophene-based covalent organic frameworks with spatially separated redox centers are rationally designed for the photocatalytic production of hydrogen peroxide from water and oxygen without sacrificial agents. The triazine-containing framework demonstrates high selectivity for H₂O₂photogeneration, with a yield rate of 2111 μM h⁻¹(21.11 μmol h⁻¹and 1407 μmol g⁻¹h⁻¹) and a solar-to-chemical conversion efficiency of 0.296%. Codirectional charge transfer and large energetic differences between linkages and linkers are verified in the double donor-acceptor structures of periodic frameworks. The active sites are mainly concentrated on the electron-acceptor fragments near the imine bond, which regulate the electron distribution of adjacent carbon atoms to optimally reduce the Gibbs free energy of O₂* and OOH* intermediates during the formation of H₂O₂.

2D materials show many particular properties, such as high surface‐to‐volume ratio, high anisotropic degree, and adjustable chemical functionality. These unique properties in 2D materials have sparked immense interest due to their applications in photocatalytic systems, resulting in significantly enhanced light capture, charge‐transfer kinetics, and surface reaction. Herein, the research progress in 2D photocatalysts based on varied compositions and functions, followed by specific surface modification strategies, is introduced. Fundamental principles focusing on light harvesting, charge separation, and molecular adsorption/activation in the 2D‐material‐based photocatalytic system are systemically explored. The examples described here detail the use of 2D materials in various photocatalytic energy‐conversion systems, including water splitting, carbon dioxide reduction, nitrogen fixation, hydrogen peroxide production, and organic synthesis. Finally, by elaborating the challenges and possible solutions for developing these 2D materials, the review is expected to provide some inspiration for the future research of 2D materials used on efficient photocatalytic energy conversions.

The artificial photosynthesis of hydrogen peroxide (H₂O₂) is of great interest, yet simultaneously boosting the oxygen reduction reaction (ORR) while maintaining an efficient water oxidation reaction (WOR) poses a significant challenge. Herein, we present an innovative strategy to construct precisely engineered photocatalysts with adjacent dual active sites, which effectively promote both the ORR and WOR. Specifically, isolated tungsten (W) atoms are strategically positioned next to the triazine rings of polymeric carbon nitride, creating synergistic reactive regions with complementary ORR and WOR activities. Through a combination of experimental investigations and theoretical simulations, we demonstrate that by tuning the isolated W species, the adjacent coordinating triazine units can activate a highly selective two-electron ORR pathway, facilitating the production of H₂O₂. Simultaneously, the WOR occurs at the dedicated W site, and the in situ generated O₂ is rapidly consumed by the adjacent ORR active sites. This interplay between the two active sites is crucial for improving the overall reaction kinetics. The optimized catalyst exhibits exceptional performance, with a high activity of 556 μmol g⁻¹ h⁻¹ for overall H₂O₂ production with an apparent quantum yield of 8.53% and a remarkable solar-to-chemical conversion efficiency of 0.31%, outperforming most previously reported catalysts under similar conditions. The promising efficiency in H₂O₂ generation, accomplished through the intricate design of catalysts with cooperative dual sites, broadens the avenue for converting solar energy into valuable chemical products in a sustainable and environmentally friendly manner.