Direct Z-scheme Cs2O–Bi2O3–ZnO heterostructures for photocatalytic overall water splitting

In this work, a direct Z-scheme Cs2O–Bi2O3–ZnO heterostructure without any electron mediator is fabricated by a simple solution combustion route. Cs2O is chosen as a sensitizer to expand the light absorption range, and in addition, its conduction band minimum (CBM) and valence band maximum (VBM) pos...

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Published inJournal of materials chemistry. A, Materials for energy and sustainability Vol. 6; no. 43; pp. 21379 - 21388
Main Authors Abdo Hezam, Namratha, K, Drmosh, Q A, Deepalekshmi Ponnamma, Adel Morshed Nagi Saeed, Ganesh, V, Neppolian, B, Byrappa, K
Format Journal Article
LanguageEnglish
Published Cambridge Royal Society of Chemistry 2018
Subjects
Absorption
Bismuth oxides
Bismuth trioxide
Catalysts
Cesium oxides
Conduction
Conduction bands
Current carriers
Dependence
Electrochemistry
Electromagnetic absorption
Heterostructures
Incident light
Irradiation
Migration
Photocatalysis
Photovoltaic cells
Quantum efficiency
Radiation
Redox potential
Splitting
Valence band
Water splitting
Zinc oxide
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Summary:In this work, a direct Z-scheme Cs2O–Bi2O3–ZnO heterostructure without any electron mediator is fabricated by a simple solution combustion route. Cs2O is chosen as a sensitizer to expand the light absorption range, and in addition, its conduction band minimum (CBM) and valence band maximum (VBM) positions are suitable to construct a direct Z-scheme system with ZnO and Bi2O3. Structural and elemental analyses show clear evidence for heterostructure formation. The Z-scheme charge carrier migration pathway in Cs2O–Bi2O3–ZnO is confirmed by high resolution XPS and ESR studies. The fabricated heterostructure exhibits a good ability to split water to H2 and O2 under simulated sunlight irradiation without any sacrificial agents or co-catalysts and has excellent photostability. The apparent quantum efficiency of the optimized Cs2O–Bi2O3–ZnO heterostructure reaches up to 0.92% at 420 nm. The excellent efficiency of this fabricated heterostructure is attributed to the efficient charge carrier separation, the high redox potential of the CBM and VBM benefiting from a direct Z-scheme charge carrier migration pathway and the extended light absorption range.
ISSN:2050-7488
2050-7496
DOI:10.1039/c8ta08033j