One-step fabrication of N-doped TiO2 inverse opal films with visible light photocatalytic activity

Photonic Band Gap Engineering by Varying the Inverse Opal Wall Thickness

We demonstrate the band gap programming of inverse opals by fabrication of different wall thickness by atomic layer deposition (ALD). The opal templates were synthesized using polystyrene and carbon nanospheres by the vertical deposition method. The structure and properties of the TiO2 inverse opal samples were investigated using Scanning Electron Microscope (SEM) and Focused Ion Beam Scanning Electron Microscopy (FIB-SEM), Energy Dispersive X-ray analysis (EDX), X-ray Diffraction (XRD) and Finite Difference Time Domain (FDTD) simulations. The photonic properties can be well detected by UV-Vis reflectance spectroscopy, while diffuse reflectance spectroscopy appears to be less sensitive. The samples showed visible light photocatalytic properties using Raman microscopy and UV-Visible spectrophotometry, and a newly developed digital photography-based detection method to track dye degradation. In our work, we stretch the boundaries of a working inverse opal to make it commercially more available while avoiding fully filling and using cheaper, but lower-quality, carbon nanosphere sacrificial templates.

Engineered inverse opal structured semiconductors for solar light-driven environmental catalysis

Inverse opal (IO) macroporous semiconductor materials with unique physicochemical advantages have been widely used in solar-related environmental areas. In this minireview, we first summarize the synthetic methods of IO materials, emphasizing the two-step and three-step approaches, with the typical physicochemical properties being compared where applicable. We subsequently discuss the application of IO semiconductors (e.g., TiO₂, ZnO, g-C₃N₄) in various photo-related environmental techniques, including photo- and photoelectro-catalytic organic pollutant degradation in water, optical sensors for environmental monitoring, and water disinfection. The engineering strategies of these hierarchical structures for optimizing the activities for different catalytic reactions are discussed, ranging from heterojunction construction, cocatalyst loading, and heteroatom doping, to surface defect construction. Structure-activity relationships are established correspondingly. With a systematic understanding of the unique properties and catalytic activities, this review is expected to orient the design and structure optimization of IO semiconductor materials for photo-related performance improvement in various environmental techniques. Finally, the challenges of emerging IO structured semiconductors and future development directions are proposed.

3D macroporous TiO2inverse opal binary and ternary composite materials and their photocatalytic activity

We have fabricated binary and ternary 3D macroporous composite materials containing inverse opal TiO₂, gold nanoparticles and nanosized cadmium sulfide on glass slides and these materials show excellent photocatalytic activity.

N-doped mesoporous inverse opal structures for visible-light photocatalysts

N-doped, mesoporous IO TiO₂ structures were fabricated as visible-light photocatalysts.