The role of luminescence self-absorption in photocatalytic properties of self-assembled ZnS nanocrystals

J Zhang,Y L Tang,X R Wang,L Yang,Z C Su,Y T Bao,Y Cui,X Z Lao,J Y Xu,S J Xu

doi:10.1063/5.0020856

Abstract

In this work, we used a template-free method to synthesize zinc sulfide (ZnS) materials. The photocatalytic performances of the samples were evaluated, and the physical natures of the ZnS nanocrystals were determined by photoluminescence (PL). Interestingly, the temperature-dependent PL variations of the samples were very different in connection with the synthesis condition. Combined with a series of catalytic experiments, it suggested that the intrinsic self-absorption of PL and photon recycling play key roles in photocatalysis. This work gives a new idea for understanding the photocatalysis and presents a new strategy to design ZnS related photocatalysts for further applications.

Highlights

The narrow light absorption range and the direct bandgap, which is conducive to the radiation recombination of the photogenic electron–hole pairs, limit its photocatalytic efficiency, restricting its catalytic efficiency
Defects may act as recombination centers, hampering the photocatalytic activity
The photocatalytic activities of the Zinc sulfide (ZnS) samples were evaluated by a series of experiments under different conditions, and the physical characteristics were studied by photoluminescence (PL) in detail

Summary

Introduction

Zinc sulfide (ZnS) is a good candidate for photocatalysis, which has attracted great attention recently.1–3 the narrow light absorption range and the direct bandgap, which is conducive to the radiation recombination of the photogenic electron–hole pairs, limit its photocatalytic efficiency, restricting its catalytic efficiency.4–6 several attempts have been made to improve its catalytic performance.7–18 As for photocatalysts, the intrinsic natures such as crystalline phases, defect states, etc., are crucial for the photocatalytic activities.4,19–21 For example, in photocatalysts, defects may serve as active sites capturing and trapping photogenerated carriers and, promote the catalytic performance.8,9,18 On the other hand, defects may act as recombination centers, hampering the photocatalytic activity.19 it is crucial to understand the intrinsic nature of ZnS to design related photocatalysts. The photocatalytic activities of the ZnS samples were evaluated by a series of experiments under different conditions, and the physical characteristics were studied by photoluminescence (PL) in detail. These results indicated that the preparing temperature greatly influenced the sizes and morphologies of the ZnS specimens.

Results

Conclusion