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Nanomaterials have been widely used in the fields of photocatalysis, sensors, and solar cells due to their excellent properties. However, nanomaterials are mainly prepared under nonlimited conditions. With the development of biomimetic nanochannels, their gating properties and chemical stability have come to the fore. Inspired by the potential applications of biomimetic nanochannels, it is significant to synthesize nanomaterials inside biomimetic nanochannels under limited conditions for facilitating newer applications. Therefore, we used an anodic aluminum oxide (AAO) template with different pore diameters as the limited condition to synthesize CdS structures via different synthesis methods. We successfully synthesized CdS nanoparticles and flower-like CdS structures in AAO nanochannels by the electrochemical-assisted method or solution impregnation method. Field-emission scanning electron microscope (FESEM) results revealed that the CdS nanoparticles would agglomerate together to form irregular bulks with an increase in the applied voltage; flower-like CdS structures would block the AAO nanochannels for longer reaction times and higher concentrations. Energy-dispersive spectrometer (EDS) and X-ray diffraction (XRD) results revealed that these structures self-assembled into AAO nanochannels were, in fact, CdS. In conclusion, these methods can provide important guidelines for nanomaterial synthesis in AAO nanochannels.

The integration of photocatalytic materials and self-cleaning superhydrophobic materials provides a possibility of combining decontamination and antifouling. Herein, considering the ability of TiO2 in the photocatalytic degradation of pollutants, morphology-controllable TiO2 nanotube arrays (TNAs) were successfully synthesized by adjusting the anodizing and annealing parameters of anodic oxidation. On this basis, superhydrophobic states on 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PTES)-modified TNAs and stearic acid (SA)-modified TNAs were fabricated by means of a facile impregnation method. The TNAs prior to and after modification were characterized by powder X-ray diffraction (XRD) for determining the phase structure, field emission scanning electron microscopy (FESEM) for determining the surface morphology, energy dispersive spectroscopy (EDS) for determining the chemical composition, ultraviolet-visible spectroscopy (UV-Vis) for determining the light absorption performance and a droplet shape analyzer (DSA) for determining surface wettability. The photocatalytic degradation efficiency of methylene blue was investigated, and the synergistic effect of photocatalysis and self-cleaning was well-established from the photocatalytic tests and self-cleaning simulation tests. Compared with untreated TNAs, the modified superhydrophobic TNAs not only maintained better photocatalytic performance, but also possessed the ability to further remove the residual pollutants on the superhydrophobic surfaces by a self-cleaning effect; thus, they have profound impacts on and potential applications in both photocatalysis and self-cleaning.

CdS is a well-known visible-light-sensitive semiconductor and has been widely used in photocatalysis. In order to improve the photocatalytic activity of CdS, controllable synthesis with different morphologies has been focused on. In this work, CdS structures with different kinds of surfactants were synthesized by the hydrothermal method. The as-prepared samples were characterized by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-Vis), and fluorescence spectroscopy (PL). Their photocatalytic activities were evaluated by the photocatalytic degradation of methylene blue (MB) under simulated visible-light irradiation. The XRD and EDS results revealed that fishbone-like CdS exhibited the hexagonal phase. The FESEM results showed that the morphologies of CdS indicated microsphere structures, flower-like structures, and branch-like structures when we added hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and polyethylene glycol (PEG 2000), respectively, as surfactants. The possible growth mechanism of CdS with different surfactants was explained. The UV-Vis results showed that the band gap of fishbone-like CdS was 2.32 eV, while the band gaps of CdS were 2.22 eV, 2.30 eV, and 2.31 eV for CTAB, SDS, and PEG 2000, respectively, when the concentration was 0.005 g mL−1. The photocatalytic results showed that the highest degradation rates of MB were 90.0%, 87.9%, and 87.5% for the different kinds of surfactants, which were consistent with the UV-Vis and PL results. The CdS microspheres displayed photocatalytic stability to MB. The trapping experiments indicated that the photogenerated electrons played a key role in the photocatalytic degradation of MB. Briefly, different kinds of surfactants have obvious effects on the structure and photocatalytic performance of CdS.