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dc.contributor.authorOpoku, Francis
dc.contributor.authorVan Sittert, Cornelia Gertina Catharina Elizabeth
dc.contributor.authorGovender, Krishna Kuben
dc.contributor.authorGovender, Penny Poomani
dc.identifier.citationOpoku, F. et al. 2017. Insights into the photocatalytic mechanism of mediator-free direct Z-scheme g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures: a hybrid density functional theory study. Applied surface science, 427 (Pt B):487-498. []en_US
dc.description.abstractGraphite-like carbon nitride (g-C3N4)-based heterostructures have received much attention due to their prominent photocatalytic activity. The g-C3N4/Bi2WO6 and g-C3N4/Bi2MoO6 heterostructures, which follow a typical hetero-junction charge transfer mechanisms show a weak potential for hydrogen evolution and reactive radical generation under visible light irradiation. A mediator-free Z-scheme g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures photocatalyst are designed for the first time using first-principles studies. Moreover, theoretical understanding of the underlying mechanism, the effects of interfacial composition and the role the interface play in the overall photoactivity is still unexplained. The calculated band gap of the heterostructures is reduced compared to the bulk Bi2WO6 and Bi2MoO6. In this study, we systematically calculated energy band structure, optical properties and charge transfer of the g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures using the hybrid density functional theory approach. The results show that the charge transfer at the interface of the heterostructures induces a built-in potential, which benefits the separation of photogenerated charge carriers. The g-C3N4/Bi2MoO6(010) heterostructure with more negative adhesion energy (−1.10 eVA−2) is predicted to have a better adsorptive ability and can form more easily compared to the g-C3N4/Bi2WO6(010) interface (−1.16 eVA−2). Therefore, our results show that the g-C3N4 interaction with Bi2MoO6 is stronger than Bi2WO6, which is also verified by the smaller vertical separation (3.25 Å) between Bi2MoO6 and g-C3N4 compared to the g-C3N4/Bi2WO6(010) interface (3.36 Å). The optical absorption verifies that these proposed Z-scheme heterostructures are excellent visible light harvesting semiconductor photocatalyst materials. This enhancement is ascribed to the role of g-C3N4 monolayer as an electron acceptor and the direct Z-scheme charge carrier transfer at the interface of the heterostructures. This work is useful for designing new types of Z-scheme photocatalyst and offers new insight into Z-scheme charge transfer mechanism for applications in the field of solar energy conversionen_US
dc.subjectAdhesion energyen_US
dc.subjectHybrid density functional theoryen_US
dc.subjectBuilt-in potentialen_US
dc.titleInsights into the photocatalytic mechanism of mediator-free direct Z-scheme g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures: a hybrid density functional theory studyen_US
dc.contributor.researchID10073817 - Van Sittert, Cornelia Gertina Catharina E.

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