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 CO 2 reduction reactions. Among the widely studied photocatalysts, g‐C 3 N 4 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‐C 3 N 4 and nanosized Fe 2 TiO 5 is successfully prepared via simple hydrothermal assembly of both pre‐synthesized semiconductors. Modifications induced on g‐C 3 N 4 during the heterojunction preparation play a crucial role in the efficiency of the CO 2 photoreduction reaction. Under simulated sunlight irradiation, the g‐C 3 N 4 /Fe 2 TiO 5 heterojunction exhibits higher photocatalytic performance than the pristine materials for both CO 2 reduction to produce CO and CH 4 , and H 2 O reduction reaction, producing H 2 . The results obtained correspond to a 1.5‐fold improvement compared to pristine g‐C 3 N 4 . 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 H 2 production, a route to renewable syngas.