scholarly journals Remarkable Photocatalytic Behavior of WO3 /MoS2 Heterostructure: Insights From a Combined Experimental and Theoretical Investigations

2021 ◽  
Author(s):  
Sulakshana Shenoy ◽  
Kishore Sridha ◽  
Kartick Tarafder
Keyword(s):  
Photocatalytic Performance ◽  
Theoretical Study ◽  
Photogenerated Electron ◽  
Blue Dye ◽  
Internal Electric Field ◽  
Electron Hole ◽  
Photocatalytic System ◽  
Theoretical Investigations ◽  
Redox Ability ◽  
Natural Photosynthesis

Abstract The Z-scheme heterogeneous photocatalytic system simulates the natural photosynthesis process and can overcome the shortcomings of the single-component photocatalyst, and possess many merits, including increased light-harvesting, spatially separated reductive and oxidative sites, and well-preserved strong redox ability, which benefits the photocatalytic performance. Here we report the fabrication of a novel WO3/MoS2 heterojunction via the hydrothermal method, with the structure, electronic and photocatalytic properties analyzed by means of experimental and theoretical methods. Photocatalytic studies have been conducted on methylene blue dye under visible light in the presence of WO3/MoS2 heterostructure, and the degradation rate was as high as 90% within 60 min of light irradiation. A detailed theoretical study of this system shows that an internal electric field at the interface of the heterojunction was formed directed from MoS2 to WO3, which helps to separate the photogenerated electron-hole pairs efficiently through a direct Z-scheme charge transfer process. This work also demonstrated the significant potential of WO3/MoS2 heterostructure towards hydrogen evolution reaction.

scholarly journals Construction of Ag3PO4/SnO2 Heterojunction on Carbon Cloth with Enhanced Visible Light Photocatalytic Degradation

2020 ◽  
Vol 10 (9) ◽  
pp. 3238
Author(s):  
Min Liu ◽  
Guangxin Wang ◽  
Panpan Xu ◽  
Yanfeng Zhu ◽  
Wuhui Li
Keyword(s):  
Visible Light ◽  
Photocatalytic Performance ◽  
Separation Efficiency ◽  
Photogenerated Electron ◽  
Carbon Cloth ◽  
Electron Hole ◽  
Step Process ◽  
Photogenerated Electrons ◽  
Rapid Transfer ◽  
Visible Light Photocatalytic

In this study, the Ag3PO4/SnO2 heterojunction on carbon cloth (Ag3PO4/SnO2/CC) was successfully fabricated via a facile two-step process. The results showed that the Ag3PO4/SnO2/CC heterojunction exhibited a remarkable photocatalytic performance for the degradation of Rhodamine B (RhB) and methylene blue (MB), under visible light irradiation. The calculated k values for the degradation of RhB and MB over Ag3PO4/SnO2/CC are 0.04716 min−1 and 0.04916 min−1, which are higher than those calculated for the reactions over Ag3PO4/SnO2, Ag3PO4/CC and SnO2/CC, respectively. The enhanced photocatalytic activity could mainly be attributed to the improved separation efficiency of photogenerated electron-hole pairs, after the formation of the Ag3PO4/SnO2/CC heterojunction. Moreover, carbon cloth with a large specific surface area and excellent conductivity was used as the substrate, which helped to increase the contact area of dye solution with photocatalysts and the rapid transfer of photogenerated electrons. Notably, when compared with the powder catalyst, the catalysts supported on carbon cloth are easier to quickly recycle from the pollutant solution, thereby reducing the probability of recontamination.

scholarly journals Preparation and Photocatalytic Performance for Degradation of Rhodamine B of AgPt/Bi4Ti3O12 Composites

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2206
Author(s):  
Gaoqian Yuan ◽  
Gen Zhang ◽  
Kezhuo Li ◽  
Faliang Li ◽  
Yunbo Cao ◽  
...  
Keyword(s):  
Visible Light ◽  
Noble Metal ◽  
Rhodamine B ◽  
Photocatalytic Performance ◽  
Bimetallic Nanoparticles ◽  
Resonance Effect ◽  
Visible Region ◽  
Photogenerated Electron ◽  
Pt Nanoparticles ◽  
Electron Hole

Loading a noble metal on Bi4Ti3O12 could enable the formation of the Schottky barrier at the interface between the former and the latter, which causes electrons to be trapped and inhibits the recombination of photoelectrons and photoholes. In this paper, AgPt/Bi4Ti3O12 composite photocatalysts were prepared using the photoreduction method, and the effects of the type and content of noble metal on the photocatalytic performance of the catalysts were investigated. The photocatalytic degradation of rhodamine B (RhB) showed that the loading of AgPt bimetallic nanoparticles significantly improved the catalytic performance of Bi4Ti3O12. When 0.10 wt% noble metal was loaded, the degradation rate for RhB of Ag0.7Pt0.3/Bi4Ti3O12 was 0.027 min−1, which was respectively about 2, 1.7 and 3.7 times as that of Ag/Bi4Ti3O12, Pt/Bi3Ti4O12 and Bi4Ti3O12. The reasons may be attributed as follows: (i) the utilization of visible light was enhanced due to the surface plasmon resonance effect of Ag and Pt in the visible region; (ii) Ag nanoparticles mainly acted as electron acceptors to restrain the recombination of photogenerated electron-hole pairs under visible light irradiation; and (iii) Pt nanoparticles acted as electron cocatalysts to further suppress the recombination of photogenerated electron-hole pairs. The photocatalytic performance of Ag0.7Pt0.3/Bi4Ti3O12 was superior to that of Ag/Bi4Ti3O12 and Pt/Bi3Ti4O12 owing to the synergistic effect between Ag and Pt nanoparticles.

NiFe-LDH@ZnO@NF composite for photo-degradation of Rhodamine B dye

MRS Advances ◽  
2019 ◽  
Vol 4 (33-34) ◽  
pp. 1887-1893
Author(s):  
Jun Wu ◽  
Yonghui Gong ◽  
Qiang Fu ◽  
Chunxu Pan
Keyword(s):  
Rhodamine B ◽  
Photocatalytic Performance ◽  
Nickel Foam ◽  
Photogenerated Electron ◽  
Chemical Compositions ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Photo Degradation ◽  
Potential Applications ◽  
Rhodamine B Dye

ABSTRACTIn this paper, a novel NiFe-LDH@ZnO composite was prepared by using a facile two-step process upon nickel foam (NF) substrate. The morphologies and chemical compositions of the samples were characterized by SEM, EDS, XRD and XPS. Photocatalytic degradation of Rhodamine B dye was tested with the samples NiFe-LDH@ZnO@NF, ZnO@NF and NiFe-LDH under the same conditions. The experimental results revealed that the NiFe-LDH@ZnO@NF composite exhibited excellent photocatalytic performance, i.e., 1.4 and 2.5 times higher than that of pure ZnO and NiFe-LDH, respectively. The reason was that the NiFe-LDH@ZnO@NF composite provided a possibility to effectively inhibit the recombination of the photogenerated electron-hole pairs, and therefore enhanced the photocatalytic efficiency. This composite is expected to have potential applications in wastewater treatment field.

scholarly journals Ag as Cocatalyst and Electron-Hole Medium in CeO2 QDs/Ag/Ag2Se Z-scheme Heterojunction Enhanced the Photo-Electrocatalytic Properties of the Photoelectrode

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 253 ◽  
Author(s):  
Lingwei Li ◽  
Hange Feng ◽  
Xiaofan Wei ◽  
Kun Jiang ◽  
Shaolin Xue ◽  
...  
Keyword(s):  
High Speed ◽  
Oxygen Vacancies ◽  
Photocatalytic Performance ◽  
Interfacial Region ◽  
Photogenerated Carrier ◽  
Electron Hole ◽  
Carrier Recombination ◽  
Photocatalytic System ◽  
Nano Channel ◽  
Active Substances

A recyclable photoelectrode with high degradation capability for organic pollutants is crucial for environmental protection and, in this work, a novel CeO2 quantum dot (QDs)/Ag2Se 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% CeO2 QDs/Ag2Se 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 CeO2 QDs advance the separation and transfer of photogenerated carriers at the interfacial region. Free radical capture tests demonstrate that •O2−, •OH, and h+ are the principal active substances and, by also considering the bandgaps of CeO2 QDs and Ag2Se, the photocatalytic mechanism of CeO2 QDs/Ag2Se 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.

scholarly journals Synthesis and characterization of black TiO2/graphene composites with enhanced photocatalysis

2020 ◽  
Author(s):  
Zhaoqing Li ◽  
Zhufeng Liu ◽  
Xiao Yang ◽  
Peng Chen ◽  
Lei Yang ◽  
...  
Keyword(s):  
Visible Light ◽  
Photocatalytic Performance ◽  
Sol Gel ◽  
Photogenerated Electron ◽  
Catalytic Performance ◽  
Attractive Potential ◽  
Electron Hole ◽  
Hole Recombination

Abstract According to the composite design, a series of black TiO2/graphene composites were synthesized to improve its photocatalytic activity. TiO2 is generated in situ on the surface of graphene by a facile sol-gel method. The combination of graphene and TiO2 was beneficial for eliminating the opportunity of photogenerated electron-hole recombination due to the excellent conductivity of graphene. In the subsequent hydrogenation process, the self-doping Ti3+ was introduced accompanied by the crystallization of amorphous TiO2. The narrowed bandgap caused by self-doping Ti3+ enhanced the visible light absorption and make the composites appear black. Both of them improved the photocatalytic performance of the synthesized black TiO2/graphene composites. The band structure of the composite was analyzed by valence band XPS, revealing the reason for the high visible light catalytic performance of the composite. The results proved that the black TiO2/graphene composites synthesized show attractive potential for applications in environmental and energy issues.

Surface oxygen vacancy and defect engineering of WO3 for improved visible light photocatalytic performance

2018 ◽  
Vol 8 (17) ◽  
pp. 4399-4406 ◽  
Author(s):  
Qi Liu ◽  
Fengjiao Wang ◽  
Huaxiang Lin ◽  
Yanyu Xie ◽  
Na Tong ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Visible Light ◽  
Photocatalytic Performance ◽  
Photogenerated Electron ◽  
Vacancy Defect ◽  
Surface Oxygen ◽  
Defect Engineering ◽  
Electron Hole ◽  
Surface Oxygen Vacancy ◽  
Visible Light Photocatalytic

Compared to the pristine WO3, the oxygen vacancy defect levels of the sub-stoichiometric WO3−X narrow the bandgap and promote the separation of photogenerated electron–hole pairs.

scholarly journals Highly effective photocatalytic performance of {001}-TiO2/MoS2/RGO hybrid heterostructures for the reduction of Rh B

RSC Advances ◽  
2019 ◽  
Vol 9 (26) ◽  
pp. 15033-15041 ◽  
Author(s):  
Ya Gao ◽  
Yongjie Zheng ◽  
Jixing Chai ◽  
Jingzhi Tian ◽  
Tao Jing ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Photocatalytic Performance ◽  
Photogenerated Electron ◽  
High Catalytic Activity ◽  
Electron Hole ◽  
Co Catalysts ◽  
Effective Separation ◽  
Key Features ◽  
Rapid Transfer ◽  
Photocatalytic Materials

Effective separation and rapid transfer of photogenerated electron–hole pairs are key features of photocatalytic materials with high catalytic activity, which could be achieved by co-catalysts.

scholarly journals A metal-free 3C-SiC/g-C3N4 composite with enhanced visible light photocatalytic activity

RSC Advances ◽  
2017 ◽  
Vol 7 (63) ◽  
pp. 40028-40033 ◽  
Author(s):  
Hao Xu ◽  
Zhixing Gan ◽  
Weiping Zhou ◽  
Zuoming Ding ◽  
Xiaowei Zhang
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Light Absorption ◽  
Carbon Nitride ◽  
Photocatalytic Performance ◽  
Photogenerated Electron ◽  
Electron Hole ◽  
Visible Light Absorption ◽  
Metal Free ◽  
Visible Light Photocatalytic

Insufficient visible light absorption and fast recombination of the photogenerated electron–hole pairs have seriously hampered the photocatalytic performance of graphitic carbon nitride (g-C3N4) up to now.

Synthesis of g-C3N4/CuS Heterojunction with Enhanced Photocatalytic Activity Under Visible-Light

2020 ◽  
Vol 20 (9) ◽  
pp. 5896-5905
Author(s):  
Fan Wang ◽  
Qingru Zeng ◽  
Jinping Tang ◽  
Liang Peng ◽  
Jihai Shao ◽  
...  
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Separation Efficiency ◽  
Photocatalytic Property ◽  
Photogenerated Electron ◽  
Light Irradiation ◽  
Electron Hole ◽  
Photocatalytic System ◽  
Composite Photocatalysts ◽  
The Stability

Novel g-C3N4/CuS hybrid photocatalysts were synthesized successfully via a facile hydrothermal method. Characterization results of the photocatalysts showed that especial heterostructure had formed between g-C3N4 and CuS, and possess suitable matched band potential. The composite photocatalysts displayed strong UV-visible light absorption ability in the range from 200 to 800 nm. Photocatalytic performance of the photocatalysts were evaluated via photooxidation of methyl orange (MO) under visible-light irradiation. Hybrid photocatalysts showed better photocatalytic properties than that of pure g-C3N4 or CuS. The 60% g-C3N4/CuS sample proved the supreme photocatalytic property. The integrated g-C3N4 and CuS heterojunction elevated the separation efficiency of photogenerated electron–hole pairs, and increased the photo-decoloration efficiency of MO under visible-light irradiation. A four-cycle repeatability experiment was carried out to investigate the stability of hybrid photocatalysts in the photocatalyst reaction. Radical capture experiments proved that photogenerated e−, h+ and .OH were responsible for MO photo-decoloration. In addition, the potential mechanism of the photocatalytic system g-C3N4/CuS+H2O2+vis are presented.

Enhanced visible light photocatalytic activity of AgI/TiO2 composite fabricated by a grinding method

2019 ◽  
Vol 54 (3) ◽  
pp. 257-264
Author(s):  
Jin Xu ◽  
Dasheng Gao ◽  
Shuang Cui ◽  
Xiaohua Wang ◽  
Ningning Liu
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Active Sites ◽  
Photocatalytic Performance ◽  
Photogenerated Electron ◽  
Active Species ◽  
Electron Hole ◽  
Grinding Method ◽  
The Stability ◽  
Visible Light Photocatalytic

Abstract Through a simple grinding method, AgI/TiO2 composites were successfully synthesized. The as-prepared AgI/TiO2 composites were used as photocatalysts for Rhodamine B (RhB) degradation under visible light irradiation and exhibited excellent photocatalytic performance. In the presence of composites, almost 100% RhB was decomposed after 60 min. The photocatalytic activity of AgI/TiO2-0.5 composite was optimal, which was 9.5 times higher than that of pristine TiO2, and 15.6 times higher than that of AgI. Moreover, experimental results revealed that the improved photocatalytic activity was not only ascribed to the loading AgI but also resulted from the method that enabled the exposure of more active sites in the composites. In addition, the intimate interfacial contact obtained by this method could also promote the efficient separation of photogenerated electron-hole pairs. Moreover, the possible photocatalytic active species and the stability of the photocatalyst were investigated in detail.

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