Design and Development of Bismuth Oxyhalides Photocatalysts with High Solar-energy Conversion Efficiency

Benefiting from the two-dimensional (2D) layered structure, bismuth oxyhalides BiOX (X: Br, Cl) are promising excellent photocatalysts in photocatalytic O2 evolution and dye degradation. Unfortunately, the application of BiOX is limited into the ultraviolet light (UV) region as BiOX has an indirect wide band-gap with the value of about 3.2 eV. Thus, developing approaches to extend the absorption of BiOX into visible or near-infrared (NIR) light region is highly demanded in enhancing the photocatalytic performance of BiOX. In this thesis, three different strategies, including fabricating BiOCl with oxygen vacancies, constructing heterogeneous structures between novel metal and BiOCl and constructing heterogeneous structures between upconversion particle and BiOCl, were adopted to extend the solar light harvesting of BiOCl into visible and NIR region. The photocatalytic reactions including photocatalytic water splitting and dye degradation were used to evaluate whether the photocatalytic performance of the designed systems with BiOCl was improved due to the enhanced solar light harvesting. The epitaxial heterostructure with ZnO and upconversional particles was also investigated to explore whether the strategy involving upconversion materials is applicable to extend the solar utilization of other semiconductors.