Synergistic Interfacial Engineering of Green TiO ₂ @g-C ₃ N ₄ for Noble-Metal-Free Photocatalytic H ₂ Generation under Natural Sunlight

The plausible design for accurate, sunlight-responsive photocatalysts for feasible hydrogen generation remains a critical focus in solar energy conversion exploration. In this work, a green TiO₂@g-C₃N₄ heterojunction was produced and systematically assessed for enhanced photocatalytic H₂ evolution in an aqueous glycerol solution according to direct sunlight. Structural, morphological, and interfacial features were extensively determined utilizing TEM, XPS, and photoluminescence (PL) spectroscopy, verifying the accomplished generation of a robust heterojunction with strong Ti-N-C interfacial bonding. Gas chromatography confirmed the absence of H₂ and O₂ prior to irradiation, guaranteeing precise baseline assessments. Pristine g-C₃N₄ and green TiO₂ displayed hydrogen generation rates of 3.75 and 44.5 μmolh^-1, respectively, while green TiO₂ most notably surpassed traditional white TiO₂ (<40 μmolh^-1) owing to oxygen vacancies boosting visible-light absorption. Interestingly, the designed green TiO₂@g-C₃N₄ heterostructure attained a superior H₂ evolution rate of 110.25 μmol h^-1, a 29.4- and 2.4-fold improvement over g-C₃N₄ and green TiO₂, respectively. This elevated photocatalytic achievement is credited to escalated interfacial charge movement, prolonged charge carrier lifetimes, and upgraded surface redox kinetics. This work offers beneficial insights into the rational design of g-C₃N₄-based heterostructures for highly effective, noble-metal-free, solar-driven hydrogen production.