Elsevier

Advanced Powder Technology

Volume 30, Issue 10, October 2019, Pages 2363-2368
Advanced Powder Technology

Original Research Paper
Cu7.2S4 nanosheets decorated on the {3 3 2} high index facets of Cu2O with controllable oxygen defects and enhanced photocatalytic activity

https://doi.org/10.1016/j.apt.2019.07.019Get rights and content

Highlights

  • The heterostructure of Cu7.2S4 nanosheets/trisoctahedron Cu2O are fabricated.

  • The oxygen defects content is dependent on the thickness of Cu7.2S4 nanosheets.

  • Cu7.2S4 (10 nm)/Cu2O show higher catalytic activity for MO decoloration.

Abstract

The heterostructure of Cu7.2S4 nanosheets/trisoctahedron Cu2O were successfully constructed on the {3 3 2} high-index facets of Cu2O. The results show that oxygen defects amount of the Cu7.2S4/Cu2O samples are closely related to the thickness of Cu7.2S4 nanosheets. Compared with the unmodified cuprous oxide and the Cu7.2S4/Cu2O modified with thick Cu7.2S4 nanosheets, the Cu7.2S4/Cu2O grafted with 10 nm thickness of Cu7.2S4 show higher oxygen defects content and photocatalytic performance for MO decoloration. UV–VIS DRS and PL detection show that the Cu7.2S4 nanosheets grafting on Cu2O with high-index facets accelerates the charge carrier separation, which results in an elevated degradation properties for MO.

Graphical abstract

The heterostructure of Cu7.2S4 nanosheets/trisoctahedron Cu2O are successfully fabricated via a simple Na2S etching on the {3 3 2} high-index facets of Cu2O. The Cu7.2S4/Cu2O grafted with 10 nm thickness of Cu7.2S4 show higher oxygen defects content and photocatalytic performance for MO decoloration.

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Introduction

Currently, semiconductor photocatalysts have attracted extensive attention owing to their potential applications for resolving the environmental and energy problems [1], [2], [3]. As one type of important semiconductor, cuprous oxide (Cu2O), is generally acknowledged as a promising photocatalyst due to its cleanliness, low cost, and good availability [4], [5], [6]. Thus, various Cu2O catalysts were constructed via modulating their composition, crystal facet and surface defect, etc [7], [8], [9]. To date, although plentiful nano/micro Cu2O have been designed, the use of Cu2O is still limited owing to the low conversion efficiency of photo-generated charge carriers. Therefore, it is still necessary to develop new strategies for increasing the efficiency of photo-induced carriers.

Heterojunction has been confirmed to have the potential to enhance the separation efficiency of carriers [10], [11], [12]. Thus, numerous heterojunctions of Cu2O coupled with other materials, such as CuS, ZnO and CdS, have been constructed and presented an enhanced photocatalytic performance [13], [14], [15]. Recent studies indicate that the performance of heterojunction are affected not only by the grafting body composition but also by its microstructure. Among various microstructure, 2D nanosheets, have been demonstrated holding special promoting effect for shorting the diffusion length and increasing the separation efficient of carriers [16], [17]. Nevertheless, compared with the acquired evolution of the heterojunctions [18], [19], [20], the 2D nanosheets grafted on the high-energy facets of Cu2O has not been reported. Since the high-energy facets often have high surface energy, such facets are expected to accelerate the formation rate of heterojunction and then to produce the 2D nanosheets grafted on them during the liquid-solid phase reaction. Such 2D nanosheets grafted on the high-energy facets is expected to generate an enhanced light conversion efficiency. Here, the Cu7.2S4 nanosheets were firstly constructed on the high-energy facets of the trisoctahedron Cu2O by a facile wet chemical method. The trisoctahedron Cu2O microcrystals with {3 3 2} high-index facets were firstly prepared by our previous report [21], which was used to construct the Cu7.2S4/Cu2O. Moreover, the photocatalytic activities of the resulted samples were tested.

Section snippets

Synthesis of Cu7.2S4/Cu2O

The concave trisoctahedron Cu2O was prepared firstly by reference to our previous research [21]. For the synthesis of Cu7.2S4/Cu2O, 0.1 g of the resulted trisoctahedron Cu2O powder was added to a 40 mL deionized water to make a suspension. Then 100 mL of different concentration of Na2S·9H2O solution (0.0025 M, 0.0050 M and 0.0075 M) were added, respectively. After being stirred for 10 min, the obtained precipitate was collected and washed with deionized water and ethanol three times. Then the

Analysis of morphologies and compositions

The morphologies and compositions of the samples were characterized by SEM, HRTEM and EDS; results are showed in Fig. 1. As can be seen in Fig. 1A, the trisoctahedron Cu2O microcrystal with distinct concave was prepared successfully. According to our previous report [21], we know that the 24 inclined surfaces are assigned to {3 3 2} high-index facets. When the Cu2O microcrystals were treated by Na2S solution with different concentrations, various nanosheets with different thickness presented on

Conclusions

In conclusion, the Cu7.2S4 nanosheets decorated trisoctahedron Cu2O heterostructure have been successfully fabricated via a simple Na2S etching and growing on the high-energy facets of Cu2O. The effects of the Na2S contents on the structure and catalytic performance of the Cu7.2S4/Cu2O sampled were studied in detail. The result shows that the crucial influencing factor (oxygen defects content) for the photocatalyst is heavily depended on the thickness of Cu7.2S4 nanosheets for the as-prepared

Acknowledgements

This study is funded by National Nature Science Foundation of China (51572004 and 21801003), University Natural Science Research Project of Anhui Province, China (KJ2016SD06), Top-notch Talent Cultivation Plan of Anhui Polytechnic University, China (2016BJRC002), Natural Science Fund for Distinguished Young Scholars of Anhui Polytechnic University, China (2016JQ01) and National College Student Innovation Imbark Training Program Foundation of China (201710363176).

References (26)

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