title: Uncovering the Key Role of the Fermi Level of the Electron Mediator in a Z-Scheme Photocatalyst by Detecting the Charge Transfer Process of WO3-metal-gC3N4 (Metal = Cu, Ag, Au).
abstract: Z-scheme photocatalytic system shows superiority in degradation of refractory pollutants and water splitting due to the high redox capacities caused by its unique charge transfer behaviors. As a key component of Z-scheme system, the electron mediator plays an important role in charge carrier migration. According to the energy band theory, we believe the interfacial energy band bendings facilitate the electron transfer via Z-scheme mechanism when the Fermi level of electron mediator is between the Fermi levels of Photosystem II (PS II) and Photosystem I (PS I), whereas charge transfer is inhibited in other cases as energy band barriers would form at the semiconductor-metal interfaces. Here, this inference was verified by the increased hydroxyl radical generation and improved photocurrent on WO3-Cu-gC3N4 (with the desired Fermi level structure), which were not observed on either WO3-Ag-gC3N4 or WO3-Au-gC3N4. Finally, photocatalytic degradation rate of 4-nonylphenol on WO3-Cu-gC3N4 was proved to be as high as 11.6 times than that of WO3-gC3N4, further demonstrating the necessity of a suitable electron mediator in Z-scheme system. This study provides scientific basis for rational construction of Z-scheme photocatalytic system.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology , Dalian 116024, China.
authors.forename: Houfen
authors.initials: H
authors.lastname: Li
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology , Dalian 116024, China.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Yu
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology , Dalian 116024, China.
authors.forename: Xie
authors.initials: X
authors.lastname: Quan
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology , Dalian 116024, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Chen
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology , Dalian 116024, China.
authors.forename: Yaobin
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D002384:Catalysis; D003460:Crystallization; D004560:Electricity; D004583:Electrons; D017665:Hydroxyl Radical; D008027:Light; D008670:Metals / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D012972:Sodium Hydroxide / Q000737:chemistry; D012996:Solutions; D013816:Thermodynamics; D013997:Time Factors; D014414:Tungsten / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D008670:Metals; D010087:Oxides; D010636:Phenols; D012996:Solutions; D017665:Hydroxyl Radical; D012972:Sodium Hydroxide; C511604:tungsten oxide; C041594:4-nonylphenol; D014414:Tungsten
keywords: Fermi level; Z-scheme; charge transfer; electron mediator; photocatalysis