Self-assembled three-dimensional BiOI microspheres composed of nanoplatelets were synthesized at low temperature using ethanol–water mixed solvent as reaction media and NH₃·H₂O as pH adjustment. The as-prepared BiOI was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, and nitrogen sorption. The possible formation mechanism for the architectures was discussed. It was found that mixed solvent and alkali play key roles in the formation of BiOI microspheres. The photocatalytic activity of the as-prepared sample was evaluated by degradation of phenol in aqueous solution under visible light irradiation. The BiOI microspheres show much higher photocatalytic activity than the random BiOI platelets. The total organic carbon measurement after the degradation process indicated that phenol was effectively mineralized over the BiOI microspheres. In addition, the BiOI microspheres are stable during the reaction and can be used repeatedly. The high catalytic performance of the BiOI microspheres comes from their narrow band gap, high surface area and high surface-to-volume ratio.

Spherical Bi₂MoO₆ nanoarchitectures with scale of 500 nm–2 μm were prepared by a solvothermal reaction using bismuth nitrate and ammonium molybdate as precursors. Ag₃PO₄ nanoparticles were then deposited onto the surface of Bi₂MoO₆via a facile deposition–precipitation technique. The photocatalytic tests display that the Ag₃PO₄/Bi₂MoO₆ nanocomposites possess a much higher rate for degradation of rhodamine B and methylene blue than the pure Ag₃PO₄ nanoparticles and Bi₂MoO₆ under visible light. The catalytic activity of the composite photocatalysts is greatly influenced by the loading level of Ag₃PO₄. The 50 mol% Ag₃PO₄-loaded Bi₂MoO₆ spheres exhibit the highest photocatalytic activity in both the decolorization of RhB and MB. The observed improvement in photocatalytic activity is associated with the extended absorption in the visible light region resulting from the Ag₃PO₄ nanoparticles, and the effective separation of photogenerated carriers at the Ag₃PO₄/Bi₂MoO₆ interfaces. In addition, the composite can be easily reclaimed by sedimentation without any loss of its stability. Moreover, the tests of radical scavengers confirmed that h⁺ and ˙OH were the main reactive species for the degradation of RhB.

In this article, we discuss functional hybrid materials based on carbon nanotubes (CNTs) and metal oxides. The unique geometric nanostructure and electrical properties of CNTs significantly promote the dispersion of oxides with strong interaction. The improvement effect of CNTs on the performance of hybrid materials for supercapacitors, lithium ion batteries, electroanalysis and photocatalysis is addressed. The applications of CNT-oxide hybrid materials for solar cell and gas sensors are briefly introduced. The prospects and challenges for material science are also discussed.