The physical and chemical properties of sputtered HfO2−x–TiO2−x nanocolumn arrays and the photocatalytic action of high-ε (HfO2) nanocolumns for decomposition of methylene blue have been studied. Fabrication of HfO2−x–TiO2−x nanocolumn array composites by reactive sputtering without further treatment was comprehensively investigated. Well-isolated HfO2−x nanocolumns with maximum separation of approximately 500 nm and excellent orientation normal to the substrate were obtained. The coupling between HfO2−x and TiO2−x was found to be crucial for enhanced photocatalytic action; the optimal coupling was identified for HfO2−x–TiO2−x nanocolumn composites with four pairs of alternating layers, which showed better performance (by approximately 25%) under 30 W of ultraviolet (UV) irradiation, compared with TiO2−x thin films. The synergistic photocatalytic effect was predominantly attributed to defect-induced electron migration along the HfO2−x nanocolumn structure. In addition, the corresponding photoluminescence spectra and energy band diagram for the HfO2−x–TiO2−x system were used to complement the photocatalytic results.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry