Cu₂O films composed of homogeneous core–shell microspheres with multilayered shells consisting of nanoparticles, have been obtained by a simple, rapid and one-step chemical bath deposition method via the corrosive action of self-produced gluconic acid instead of a template at low temperature (80 °C). FESEM, TEM, XRD and FTIR studies show that the formation of Cu₂O films composed of homogeneous core–shell microspheres with multilayered shells mainly relies on the corrosive action of gluconic acid on the Cu₂O solid spheres, which is produced from the oxidation of the reductant glucose. The self-produced gluconic acid and the formation of corrosion channels in the microspheres are the key to the formation of the core–shell microstructure in the range of pH from 12.5 to 13.2. The photocatalytic degradation of methyl orange (MO) in aqueous suspension has been employed to evaluate the photocatalytic activity of the core–shell microsphere Cu₂O films. With the assistance of H₂O₂, the photocatalytic properties of the core–shell microsphere Cu₂O films in the degradation of MO are excellent.

The optoelectronic properties of transition metal oxide semiconductors depend on their oxygen vacancies, nanostructures and aggregation states. Here, we report the synthesis and photoluminescence (PL) properties of substoichiometric tungsten oxide (WO_3-x) aggregates with the nanorods, nanoflakes, submicro-spherical-like, submicro-spherical and micro-spherical structures in the acetic acid solution without and with the special surfactants (butyric or oleic acids). Based on theory on the osmotic potential of polymers, we demonstrate the structural change of the WO_3-x aggregates, which is related to the change of steric repulsion caused by the surfactant layers, adsorption and deformation of the surfactant molecules on the WO_3-x nanocrystals. The WO_3-x aggregates generate multi-color light, including ultraviolet, blue, green, red and near-infrared light caused by the inter-band transition and defect level-specific transition as well as the relaxation of polarons. Compared to the nanorod and nanoflake WO_3-x aggregates, the PL quenching of the submicro-spherical-like, submicro-spherical and micro-spherical WO_3-x aggregates is associated with the coupling between the WO_3-x nanoparticles and the trapping centers arising from the surfactant molecules adsorbed on the WO_3-x nanoparticles.