Photocatalytic hydrogen evolution is a developing technology that addresses the urgent energy shortage, without greenhouse gas emissions. Despite tremendous efforts over the past decades, the achievement of high-efficiency hydrogen evolution rates for application in semiconductors remains very challenging because of various factors, which include low charge mobility, low light absorption, and high charge carrier recombination. Nowadays, the built-in electric field of metal-semiconductor Schottky junctions exhibits significant developments to overcome the aforementioned limitations because of the enhanced charge separation and transportation efficiency. However, noble metals are scarce and unaffordable to limit the applications. As a promising alternative, the Ti 3 C 2 nanosheets showed excellent metal conductivity which is fascinating. A new Cd 0.5 Zn 0.5 S/Ti 3 C 2 composite was fabricated as a non-noble metal-based Schottky junction photocatalyst with enhanced H 2 production performance. For a practical exploration, this study expands its application in the realistic environment of natural seawater, which is not only more in line with the sustainable concept but also greatly alleviates the issue of limited freshwater. At present, due to the complex composition of seawater, only a few studies focus on the H 2 production of seawater. Remarkably, based on the rational design of the Cd 0.5 Zn 0.5 S/Ti 3 C 2 Schottky catalyst, the observed H 2 production rate of 9.071 mmol g −1 h −1 is thirty-three times higher than that of traditional Pt assisted photocatalyst in seawater.
Tao Junnan,Wang Mingyuan,Liu Guiwu,Liu Qinqin,Lu Lei,Wan Neng,Tang Hua,Qiao Guanjun
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 0.5 Zn 0.5 S/2D Ti 3 C 2 hybrid was fabricated by a solvothermally in-situ generated assembling method. The Cd 0.5 Zn 0.5 S nano-spheres with a fluffy surface completely and uniformly covered the ultrathin Ti 3 C 2 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 0.5 Zn 0.5 S/Ti 3 C 2 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 0.5 Zn 0.5 S, respectively. Both the multiple experimental measurements and the density functional theory (DFT) calculations further demonstrate the tight connection between Cd 0.5 Zn 0.5 S and Ti 3 C 2 , 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.
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