The phase junction of nanocomposite materials is key to enhanced performance, but is largely ignored in recent theoretical examinations of photocatalytic interactions in titania-based composites, where the focus has been on bulk band alignments. Computational advances now allow more precise modeling of the electronic and optical properties of realistic models of composites. Focusing on mixed phase anatase-rutile TiO2 as a model system, we present density functional theory (DFT) results interrogating the essential structural feature, namely the rutile-anatase interface, and its relationship to photogenerated charge localisation, bulk band alignments, and point defect formation. The interfacial region is highly disordered and localised and distinct from either rutile and anatase. This region also contains low coordinated Ti and oxygen sites and oxygen vacancies are easily formed in the interface - these are both drivers of charge localisation. The relaxations of the interface upon formation of photoexcited electrons and holes determine the final location of charges which cannot necessarily be predicted from bulk band alignments. The charge locasliation also allows the heretofore unexplained EPR data on hole locaisation to be resolved. Detailed understanding of interfacial phase junction lays the foundation for directed synthesis of highly active and efficient composite photocatalysts

Role of non-bulk interfacial structure in charge localisation in rutile-anatase TiO<sub>2</sub> composites

251st National Meeting (2016)

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Role of non-bulk interfacial structure in charge localisation in rutile-anatase TiO2 composites

Role of non-bulk interfacial structure in charge localisation in rutile-anatase TiO₂ composites