Visible-light-driven photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol over CdS@MoS2 heterostructures

Abstract

Photocatalytic hydrogen production coupled with selective oxidation of organic substrates to produce highvalue-added fine chemicals has drawn increasing attention. Herein, we report a noble metal-free photocatalyst for the highly efficient and simultaneous generation of hydrogen and the selective oxidation of benzyl alcohol into benzaldehyde over CdS@MoS 2 heterostructures under visible light. Without the need for a sacrificial agent, CdS@MoS 2 displayed an excellent hydrogen production rate of 4233 μmol g −1 h −1 with 0.3 mmol benzyl alcohol, which is approximately 53 times higher than that of bare CdS nanorods (80 μmol g −1 h −1). The reaction system was highly selective for the oxidation of benzyl alcohol into benzaldehyde. When the amount of benzyl alcohol increased to 1.0 mmol, the hydrogen production reached 9033 μmol g −1 h −1. Scanning electron microscopy and transmission electron microscopy images revealed that p-type MoS 2 sheets with a flower-like structure closely adhered to n-type semiconductor CdS nanorods through the formation of a p-n heterojunction. As a potential Z-scheme photocatalyst, the CdS@MoS 2 heterostructure effectively produces and separates electron-hole pairs under visible light. Thus, the electrons are used for reduction to generate hydrogen, and the holes oxidize benzyl alcohol into benzaldehyde. Moreover, a mechanism of photogenerated charge transfer and separation was proposed and verified by photoluminescence, electrochemical impedance spectroscopy, photocurrent and Mott-Schottky measurements. The results reveal that the CdS@MoS 2 heterojunctions have rapid and efficient charge separation and transfer, thereby greatly improving benzyl alcohol dehy-drogenation. This work provides insight into the rational design of high-performance Z-scheme photocatalysts and the use of holes and electrons to obtain two valuable chemicals simultaneously.

Zirconium-Based Metal–Organic Framework Particle Films for Visible-Light-Driven Efficient Photoreduction of CO2

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One-pot, ligand-free, room-temperature synthesis of Au/Pd/ZnO nanoclusters with ultra-low noble metal loading and synergistically improved photocatalytic performances

“…[1][2][3][4] Semiconductor photocatalysis is one of the advanced physicochemical processes applicable in the photodegradation of environmental pollutants and toxic compounds, because it is an energy-saving, environmentally friendly and efficient technology in comparison with other techniques. [5][6][7] Among the photocatalysts, zinc oxide (ZnO) has attracted considerable attention due to its low cost, nontoxicity, abundance, wide band gap, and unique optical and electronic properties. [8][9][10] However, the pristine ZnO usually exhibits low photo energy conversion efficiency probably because of its relatively low charge separation efficiency and fast recombination of photogenerated electron-hole pairs.…”

Boosting CdS Photocatalytic Activity for Hydrogen Evolution in Formic Acid Solution by P Doping and MoS2 Photodeposition

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