Highly ordered nitrogen‐doped titanium dioxide (N‐doped TiO₂) nanotube arrays were prepared by anodic oxidation method and then annealed in a N₂ atmosphere to obtain N‐doped TiO₂ nanotube arrays. The samples were characterized with scanning electron microscope (SEM), X‐ray powder diffraction (XRD), X‐ray photoelectron spectrum (XPS), and UV‐visible spectrophotometry (UV‐vis) spectrum. Degradation of the insecticide acephate under the visible light was used as a model to examine the visible‐light photocatalytic activity of N‐doped TiO₂ nanotube arrays. The results show that N type doping has no notable effects on the morphology and structure of TiO₂ nanotube arrays. After N type doping, the N replaces a small amount of O in TiO₂, forming an N–Ti–O structure. This shifts the optical absorption edge and enhances absorption of the visible light. N‐doped TiO₂ nanotube arrays subjected to annealing at 500°C in N₂ atmosphere show the strongest photocatalytic activity and reach a degradation rate of 84% within 2 h.

Phenoxazine, as an organic-small-molecule chromophore, has attracted much attention for its potential electrochromic applications recently. To develop appealing materials, phenoxazine chromophores were introduced at the N-position of carbazole–thiophene pigment, yielding two novel monomers (DTCP and DDCP), whose chemical structures were characterized by NMR, HRMS and FTIR. The results of the optical property study indicate that little influence could be observed in the presence of the phenoxazine chromophore. Corresponding polymer films on the surface of an ITO/glass electrode were obtained through electropolymerization. The electrochemical features displayed were various due to the introduction of the phenoxazine group. The spectroelectrochemical results demonstrate that the color of the polymer films could be changed. Compared with the PDDC films, the PDDCP films exhibited three different colors (tangerine, green and purple colors) in different redox states, which could be attributed to the synergistic effect between the carbazole–thiophene conjugate chain and the phenoxazine group. Moreover, fast switching time could be seen due to the presence of the phenoxazine chromophore. This study could provide a reference for obtaining high-performance electrochromic materials.