Boosting CO2 Photoreduction Efficiency of Carbon Nitride via S‐scheme g‐C3N4/Fe2TiO5 Heterojunction

Abstract Photocatalysis has emerged as an alternative to high energy‐demanding CO2 reduction reactions. Among the widely studied photocatalysts, g‐C3N4 stands out due to its composition based on earth‐abundant elements, its ability to absorb visible light, and its suitable band structure. In this study, a photocatalyst based on an S‐scheme heterojunction formed by g‐C3N4 and nanosized Fe2TiO5 is successfully prepared via simple hydrothermal assembly of both pre‐synthesized semiconductors. Modifications induced on g‐C3N4 during the heterojunction preparation play a crucial role in the efficiency of the CO2 photoreduction reaction. Under simulated sunlight irradiation, the g‐C3N4/Fe2TiO5 heterojunction exhibits higher photocatalytic performance than the pristine materials for both CO2 reduction to produce CO and CH4, and H2O reduction reaction, producing H2. The results obtained correspond to a 1.5‐fold improvement compared to pristine g‐C3N4. When [Ru(bpy)3]2+ is applied as a sensitizer, the visible light (>380 nm) activity of the photocatalytic system is restored, showing lower activity but higher selectivity toward CO and H2 production, a route to renewable syngas.