Z-scheme CdSe/ZnSe heterojunction for efficient photocatalytic hydrogen evolution

Construction heterojunction has been accepted as one of the most promising approaches to avoid charge recombination and extend light response range of a single photocatalyst, and achieve effective photocatalytic processes. Herein, a Z-scheme CdSe/ZnSe heterojunction was successfully synthesized via a simple mechanical mixing strategy. The results show that 3 wt% CdSe/ZnSe composite exhibits superior H-2 evolution activity of 15.3 mmol.h(-1).g(-1) without cocatalyst in Na2S/Na2SO3 solution, which is 4.2 and 34.1 times higher than those of ZnSe and CdSe respectively under the same conditions. The apparent quantum efficiency (AQE) is 4.0% under 400 (+/- 5) nm light irradiation. A Z-scheme charge transfer mechanism is established based on a series of trapping experiments and photochemical analyses, which is more beneficial for the charge separation as well as maintaining their relatively higher redox ability, leading to an excellent H-2 evolution activity.

Automated summary

The Z-scheme CdSe/ZnSe heterojunction was successfully synthesized via a simple mechanical mixing strategy, showing superior H-2 evolution activity in Na2S/Na2SO3 solution. The charge transfer mechanism of the Z-scheme is beneficial for charge separation and maintaining higher redox ability, leading to excellent H-2 evolution activity.