Coverage Layer Phase Composition-Dependent Photoactivity of One-Dimensional TiO-BiO Composites.

TiO-BiO composite rods were synthesized by combining hydrothermal growth of rutile TiO rod templates and sputtering deposition of BiO thin films. The TiO-BiO composite rods with β-BiO phase and α/β-BiO dual-phase decoration layers were designed, respectively, via in situ radio-frequency magnetron sputtering growth and post-annealing procedures in ambient air. The crystal structure, surface morphology, and photo-absorption performances of the pristine TiO rods decorated with various BiO phases were investigated. The crystal structure analysis reveals that the crystalline TiO-BiO rods contained β-BiO and α/β-BiO crystallites were separately formed on the TiO rod templates with different synthesis approaches. The morphology analysis demonstrates that the β-BiO coverage layer on the crystalline rutile TiO rods showed flat layer morphology; however, the surface morphology of the α/β-BiO dual-phase coverage layer on the TiO rods exhibited a sheet-like feature. The results of photocatalytic decomposition towards methyl orange dyes show that the substantially improved photoactivity of the rutile TiO rods was achieved by decorating a thin sheet-like α/β-BiO coverage layer. The effectively photoinduced charge separation efficiency in the stepped energy band configuration in the composite rods made from the TiO and α/β-BiO explained their markedly improved photoactivity. The TiO-α/β-BiO composite rods are promising for use as photocatalysts and photoelectrodes.