Abstract
ZnS is a promising photocatalyst in water purification, whereas its low photon efficiency and poor visible-light response restrict its application. Constructing composites may help solve these problems. In this work, Ag2O was introduced to ZnS for the first time based on their energy band characteristics to form a novel ZnS/Ag2O composite photocatalyst. In the model reaction of degrading methylene blue, the as-designed catalyst exhibited high catalytic activity among a series of ZnS-based composite photocatalysts under similar conditions. The catalytic rate constant was up to 0.138 min−1, which is 27.4- and 15.6-times higher than those of ZnS and Ag2O. This composite degraded 92.4% methylene blue in 50 min, while the ratios were 31.9% and 68.8% for ZnS and Ag2O. Catalytic mechanism study based on photoluminescence and radical-scavenging experiments revealed that the enhanced photocatalytic activity was attributed to the composite structure of ZnS/Ag2O. The structure not only facilitated the separation and transmission of photogenerated carriers but also extended the light response range of the catalyst. The as-designed ZnS/Ag2O composite is promising in degrading organic pollutants in water.
Highlights
Accepted: 27 May 2021Zinc sulfide (ZnS) is a promising photocatalyst which has broad applications in environmental fields, especially degrading organic pollutants and water purification [1,2,3,4,5,6,7,8]
ZnS broccoli-like microspheres were synthesized through the hydrothermal process
From the X-ray diffraction (XRD) pattern in black, it is evident that all the diffraction peaks istic diffractions of the (100), (002), (101), (110), (103), and (112) crystal planes
Summary
Accepted: 27 May 2021Zinc sulfide (ZnS) is a promising photocatalyst which has broad applications in environmental fields, especially degrading organic pollutants and water purification [1,2,3,4,5,6,7,8]. Improving its catalytic activity is hindered by two challenges: Poor visible-light response for its wide band gap [13]. Low photon efficiency for its rapid electron-hole recombination [14]. To solve these problems, many strategies have been explored [15,16,17,18,19]. Among them, combining different types of semiconductors to form composites can improve the transmitting efficiency of photogenerated carriers and extend the spectral response range [20,21,22,23]. Compositing appropriate semiconductors is an effective approach to enhance the photocatalytic activity of ZnS
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