Efficient photocatalytic hydrogen evolution coupled with benzaldehyde production over 0D Cd_0.5Zn_0.5S/2D Ti₃C₂ Schottky heterojunction

Converting water into hydrogen fuel and oxidizing benzyl alcohol to benzaldehyde simultaneously under visible light illumination is of great significance, but the fast recombination of photogenerated carriers in photocatalysts seriously decreases the conversion efficiency. Herein, a novel dual-functional 0D Cd_0.5Zn_0.5S/2D Ti₃C₂ hybrid was fabricated by a solvothermally in-situ generated assembling method. The Cd_0.5Zn_0.5S nano-spheres with a fluffy surface completely and uniformly covered the ultrathin Ti₃C₂ nanosheets, leading to the increased Schottky barrier (SB) sites due to a large contact area, which could accelerate the electron-hole separation and improve the light utilization. The optimized Cd_0.5Zn_0.5S/Ti₃C₂ hybrid simultaneously presents a hydrogen evolution rate of 5.3 mmol/(g·h) and a benzaldehyde production rate of 29.3 mmol/(g·h), which are ~3.2 and 2 times higher than those of pristine Cd_0.5Zn_0.5S, respectively. Both the multiple experimental measurements and the density functional theory (DFT) calculations further demonstrate the tight connection between Cd_0.5Zn_0.5S and Ti₃C₂, formation of Schottky junction, and efficient photogenerated electron-hole separation. This paper suggests a dual-functional composite catalyst for photocatalytic hydrogen evolution and benzaldehyde production, and provides a new strategy for preventing the photogenerated electrons and holes from recombining by constructing a 0D/2D heterojunction with increased SB sites.