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NiTiO3/Bi4NbO8Cl heterostructure photocatalysts were successfully synthesized by a mechanical mixing method. The crystal structure, morphology, optical properties and energy band structures of all samples were determined by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, ultraviolet–visible diffuse reflection spectra (UV–Vis DRS), and Mott–Schottky tests. The NiTiO3/Bi4NbO8Cl composites were observed to possess an improved activity in the photocatalytic degradation of organic dye rhodamine B (RhB) under irradiation. In particular, Bi4NbO8Cl modified with NiTiO3 (10% in weight) exhibits the best photocatalytic performance. The enhanced photocatalytic performance can be ascribed to the formation of intimate interfacial contact and type-II band alignment between NiTiO3 and Bi4NbO8Cl. From the results of photoluminescence spectra (PL), time-resolved decay spectra (TR-PL), photocurrent and electrochemical impedance spectroscopy, the rapid separation and transportation of photoinduced charge carriers were proved. In addition, the proposed mechanism for the enhanced photocatalytic activities is proposed in this paper.

A strong interfacial contact of heterostructured photocatalysts plays a key role in charges migration, thus promoting photocatalytic performance. Benefiting from the unique two-dimensional (2D) morphology and abundant terminals, 2D/2D “face-to-face” WO3·H2O/g-C3N4 heterostructured self-assemblies were fabricated employing tungsten oxide hydrate (WO3·H2O) nanoplates and graphitic carbon nitride (g-C3N4) sheets as precursors. Compared to pristine WO3·H2O and g-C3N4, the binary WO3·H2O/g-C3N4 heterostructures exhibit excellent photocatalytic performance towards water decontamination, using organic dye rhodamine B/methyl orange as probes. It is found that WO3·H2O/g-C3N4 with 20 wt% mass ratio (WHC-20) possesses the best photocatalytic activities, with about 3.05 times higher than that of pristine g-C3N4. The remarkable increase performance is attributed to the enhanced evolution of superoxide radicals (·O2−) via photoreduction in adsorbed oxygen molecules (O2−), which are promoted by efficient Z-scheme charges separation and rapid electrons transfer at 2D/2D interface. Given the low-cost, facile synthetic procedure and recycling stability, the heterostructured WO3·H2O/g-C3N4 could be served as a promising photocatalyst to deal with water contamination.

BiVO4/TiO2 nanocomposites were fabricated by a facile wet-chemical process, followed by the synthesis of TiO2 hierarchical spheres via hydrothermal method. The BiVO4/TiO2 nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The results showed that prepared TiO2 presented hierarchical spherical morphology self-assembled by nanoparticles and an anatase–brookite mixed crystal phase. The introduction of monoclinic BiVO4 components retained the hierarchical structures and expanded the light response to around 510 nm. Type II BiVO4/TiO2 heterostructured nanocomposites exhibited improved photocatalytic degradation towards methylene blue under visible-light irradiation, especially for the composite photocatalysts with atomic Ti/Bi = 10, which showed double degradation rate than that of pure BiVO4. The enhanced photocatalytic mechanism of the heterostructured BiVO4/TiO2 nanocomposites was discussed as well.

TiO2/WO3 composite nanotubes were synthesized in an anodic aluminum oxide (AAO) template by a sol–gel method. The prepared nanotubes were characterized by transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, and Brunauer–Emmett–Teller surface area. Using the nanotubes embedded in the AAO templates as catalysts, photocatalytic degradation of methyl orange aqueous solution was carried out under UV light irradiation. The results showed that the TiO2/WO3 composite nanotubes with the thickness about 50 nm could be successfully synthesized by this method. TiO2 showed anatase phase and WO3 displayed monoclinic phase. The composite nanotubes (TiO2/WO3) exhibited higher photocatalytic activity than the pure nanotubes (WO3 or TiO2). The possible reason for improving the photocatalytic activity was also discussed.

Flower-like Se nanostructures consisting of clusters of nanorods with width of 40–100 nm and length of several 100 nm have been synthesized via a carbamide-assisted hydrothermal method. The optimal clusters are composed of nanorods protruding from a central point. FESEM and TEM demonstrate the flower-like morphology. The X-ray diffraction (XRD) pattern shows that the as-prepared flower-like Se nanostructures are of hexagonal phase.