Constructing the Covalent Organic Framework and Covalently Bridged Inorganic/Organic Hybrids toward Excellent Visible-Light Photocatalytic Hydrogen Evolution

The growing demand for sustainable energy solutions has prompted significant interest in photocatalytic hydrogen production as a promising alternative to fossil fuels. Covalent organic frameworks (COFs), known for their crystalline porosity, tunable structures, and π-conjugated networks, have emerged as ideal candidates for photocatalysis. However, their limited charge separation efficiency and poor hydrophilicity hinder their full potential. This study introduces a novel ternary composite system, Ti 3 C 2 (10)@In 2 O 3 (50)@COF-3, which effectively combines the advantages of COFs, In 2 O 3, and Ti 3 C 2 to overcome these limitations. By leveraging the conductive properties of Ti 3 C 2, the active centers of In 2 O 3, and the porous nature of COFs, the composite achieves a remarkable hydrogen evolution rate of 12901.23 μmol g –1 h –1, a 14-fold increase over pure COF-3. Comprehensive structural characterizations, including PXRD, FT-IR, BET surface area measurements, and XPS, confirm the successful integration of these components and demonstrate the structural stability of the composites. The enhanced photocatalytic activity is attributed to the synergistic effects of efficient charge separation, rapid electron transport through the Ti 3 C 2 network, and improved hydrophilicity, which together promote superior photocatalytic performance. AQE values further confirm the composites’ enhanced light absorption capacity. The photocatalytic mechanism is elucidated through electrochemical impedance spectroscopy, transient photocurrent responses, and photoluminescence measurements, revealing the critical role of Ti 3 C 2 as an electron transfer conduit. This study not only highlights the successful design of multifunctional hybrid photocatalysts but also provides a promising strategy for developing highly efficient, stable, and scalable photocatalysts for sustainable hydrogen production.