Synergistic Interfacial Engineering of Green TiO2@g-C3N4for Noble-Metal-Free Photocatalytic H2Generation under Natural Sunlight

Abstract

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.