Ag as Cocatalyst and Electron-Hole Medium in CeO<sub>2</sub> QDs/Ag/Ag<sub>2</sub>Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the Photoelectrode
A recyclable photoelectrode with high degradation capability for organic pollutants is crucial for environmental protection and, in this work, a novel CeO<sub>2</sub> quantum dot (QDs)/Ag<sub>2</sub>Se Z-scheme photoelectrode boasting increased visible light absorption and fa...
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doaj-05f6f85d9e0349168848571ec552b6ac2020-11-25T03:32:40ZengMDPI AGNanomaterials2079-49912020-01-0110225310.3390/nano10020253nano10020253Ag as Cocatalyst and Electron-Hole Medium in CeO<sub>2</sub> QDs/Ag/Ag<sub>2</sub>Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the PhotoelectrodeLingwei Li0Hange Feng1Xiaofan Wei2Kun Jiang3Shaolin Xue4Paul K. Chu5College of Science, Donghua University, Shanghai 201620, ChinaCollege of Science, Donghua University, Shanghai 201620, ChinaCollege of Science, Donghua University, Shanghai 201620, ChinaCollege of Science, Donghua University, Shanghai 201620, ChinaCollege of Science, Donghua University, Shanghai 201620, ChinaDepartment of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 999077, ChinaA recyclable photoelectrode with high degradation capability for organic pollutants is crucial for environmental protection and, in this work, a novel CeO<sub>2</sub> quantum dot (QDs)/Ag<sub>2</sub>Se Z-scheme photoelectrode boasting increased visible light absorption and fast separation and transfer of photo-induced carriers is prepared and demonstrated. A higher voltage increases the photocurrent and 95.8% of tetracycline (TC) is degraded by 10% CeO<sub>2</sub> QDs/Ag<sub>2</sub>Se in 75 minutes. The degradation rate is superior to that achieved by photocatalysis (92.3% of TC in 90 min) or electrocatalysis (27.7% of TC in 90 min). Oxygen vacancies on the CeO<sub>2</sub> QDs advance the separation and transfer of photogenerated carriers at the interfacial region. Free radical capture tests demonstrate that •O<sub>2</sub><sup>−</sup>, •OH, and h<sup>+</sup> are the principal active substances and, by also considering the bandgaps of CeO<sub>2</sub> QDs and Ag<sub>2</sub>Se, the photocatalytic mechanism of CeO<sub>2</sub> QDs/Ag<sub>2</sub>Se abides by the Z-scheme rather than the traditional heterojunction scheme. A small amount of metallic Ag formed in the photocatalysis process can form a high-speed charge transfer nano channel, which can greatly inhibit the photogenerated carrier recombination, improve the photocatalytic performance, and help form a steady Z-scheme photocatalysis system. This study would lay a foundation for the design of a Z-scheme solar photocatalytic system.https://www.mdpi.com/2079-4991/10/2/253ceo<sub>2</sub> quantum dotsag<sub>2</sub>se nanoflowersz-schemecocatalystphoto-electrocatalysis |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Lingwei Li Hange Feng Xiaofan Wei Kun Jiang Shaolin Xue Paul K. Chu |
spellingShingle |
Lingwei Li Hange Feng Xiaofan Wei Kun Jiang Shaolin Xue Paul K. Chu Ag as Cocatalyst and Electron-Hole Medium in CeO<sub>2</sub> QDs/Ag/Ag<sub>2</sub>Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the Photoelectrode Nanomaterials ceo<sub>2</sub> quantum dots ag<sub>2</sub>se nanoflowers z-scheme cocatalyst photo-electrocatalysis |
author_facet |
Lingwei Li Hange Feng Xiaofan Wei Kun Jiang Shaolin Xue Paul K. Chu |
author_sort |
Lingwei Li |
title |
Ag as Cocatalyst and Electron-Hole Medium in CeO<sub>2</sub> QDs/Ag/Ag<sub>2</sub>Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the Photoelectrode |
title_short |
Ag as Cocatalyst and Electron-Hole Medium in CeO<sub>2</sub> QDs/Ag/Ag<sub>2</sub>Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the Photoelectrode |
title_full |
Ag as Cocatalyst and Electron-Hole Medium in CeO<sub>2</sub> QDs/Ag/Ag<sub>2</sub>Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the Photoelectrode |
title_fullStr |
Ag as Cocatalyst and Electron-Hole Medium in CeO<sub>2</sub> QDs/Ag/Ag<sub>2</sub>Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the Photoelectrode |
title_full_unstemmed |
Ag as Cocatalyst and Electron-Hole Medium in CeO<sub>2</sub> QDs/Ag/Ag<sub>2</sub>Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the Photoelectrode |
title_sort |
ag as cocatalyst and electron-hole medium in ceo<sub>2</sub> qds/ag/ag<sub>2</sub>se z-scheme heterojunction enhanced the photo-electrocatalytic properties of the photoelectrode |
publisher |
MDPI AG |
series |
Nanomaterials |
issn |
2079-4991 |
publishDate |
2020-01-01 |
description |
A recyclable photoelectrode with high degradation capability for organic pollutants is crucial for environmental protection and, in this work, a novel CeO<sub>2</sub> quantum dot (QDs)/Ag<sub>2</sub>Se Z-scheme photoelectrode boasting increased visible light absorption and fast separation and transfer of photo-induced carriers is prepared and demonstrated. A higher voltage increases the photocurrent and 95.8% of tetracycline (TC) is degraded by 10% CeO<sub>2</sub> QDs/Ag<sub>2</sub>Se in 75 minutes. The degradation rate is superior to that achieved by photocatalysis (92.3% of TC in 90 min) or electrocatalysis (27.7% of TC in 90 min). Oxygen vacancies on the CeO<sub>2</sub> QDs advance the separation and transfer of photogenerated carriers at the interfacial region. Free radical capture tests demonstrate that •O<sub>2</sub><sup>−</sup>, •OH, and h<sup>+</sup> are the principal active substances and, by also considering the bandgaps of CeO<sub>2</sub> QDs and Ag<sub>2</sub>Se, the photocatalytic mechanism of CeO<sub>2</sub> QDs/Ag<sub>2</sub>Se abides by the Z-scheme rather than the traditional heterojunction scheme. A small amount of metallic Ag formed in the photocatalysis process can form a high-speed charge transfer nano channel, which can greatly inhibit the photogenerated carrier recombination, improve the photocatalytic performance, and help form a steady Z-scheme photocatalysis system. This study would lay a foundation for the design of a Z-scheme solar photocatalytic system. |
topic |
ceo<sub>2</sub> quantum dots ag<sub>2</sub>se nanoflowers z-scheme cocatalyst photo-electrocatalysis |
url |
https://www.mdpi.com/2079-4991/10/2/253 |
work_keys_str_mv |
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