ZnFe2O4-BiOCl composites were prepared by both hydrothermal and direct precipitation processes and the structures and properties of the samples were characterized by various instrumental techniques. The samples were then used as catalysts for the photocatalytic reduction of CO2 in cyclohexanol under ultraviolet irradiation to give cyclohexanone (CH) and cyclohexyl formate (CF). The photocatalytic CO2 reduction activities over the hydrothermally prepared ZnFe2O4-BiOCl composites were higher than those over the directly-precipitated composites. This is because compared to the directprecipitation sample, the ZnFe2O4 nanoparticles in the hydrothermal sample were smaller and more uniformly distributed on the surface of BiOCl and so more heterojunctions were formed. Higher CF and CH yields were obtained for the pure BiOCl and BiOCl composite samples with more exposed (001) facets than for the samples with more exposed (010) facets. This is due to the higher density of oxygen atoms in the exposed (001) facets, which creates more oxygen vacancies, and thereby improves the separation efficiency of the electron-hole pairs. More importantly, irradiation of the (001) facets with ultraviolet light produces photo-generated electrons which is helpful for the reduction of CO2 to ∙CO2-. The mechanism for the photocatalytic reduction of CO2 in cyclohexanol over ZnFe2O4-BiOCl composites with exposed (001) facets involves electron transfer and carbon radical formation.

•ZnFe2O4/TiO2 nanobelts heterostructure photocatalysts were prepared by hydrothermal deposition method.•ZnFe2O4/TiO2 heterojunctions showed a higher photocatalytic activity than the pure samples.•Photocatalytic activities were tested through photocatalytic reduction CO2 in cyclohexanol.•Cyclohexyl formate and cyclohexanone were the main products.A series of ZnFe2O4/TiO2 heterostructure photocatalysts with different mass percentages of ZnFe2O4 were synthesized through hydrothermal deposition method. The photocatalysts were characterized by SEM, TEM, XRD, XPS, and UV–vis DRS techniques. It is observed that ZnFe2O4 nanoparticles grew on the TiO2 nanobelts, and the obtained nanocomposites have ordered nanobelt structure with a high crystallinity. The photocatalytic activities of the nanocomposites were tested by photocatalytic reduction of CO2 in cyclohexanol under UV light (main wave length at 360 nm) irradiation. The experimental results showed that the main products were cyclohexanone (CH) and cyclohexyl formate (CF). Compared with pure TiO2 and ZnFe2O4 samples, the obtained ZnFe2O4/TiO2 nanocomposites showed much higher photocatalytic performance. The loading amount of ZnFe2O4 was an important factor affecting the generation yields of the products. When the loading amount of ZnFe2O4 reached 9.78%, the ZnFe2O4/TiO2 heterostructure sample displayed the highest activity. The Z-scheme system reaction mechanism was proposed to explain the photocatalytic activity of the ZnFe2O4/TiO2 heterostructure sample.

Different shape of bismuth sulfide (Bi2S3), including nanoparticles, and urchin-like, microspheres hierarchical nanostructures, have been successfully fabricated using a facile and template-free solvothermal method. Their crystal and porous structures, morphologies, as well as the optical absorption were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflection spectroscopy (DRS) and nitrogen sorption. The electron microscopy observations showed that both the sulfur sources and solvents greatly affected the morphologies of the as-prepared Bi2S3. Compared with Bi2S3 nanoparticles, the hierarchical architectures exhibited higher activity for photocatalytic reduction of CO2 to methyl formate (MF) in methanol, and Bi2S3 microspheres showed the highest activity. This was attributed to their special hierarchical structure, good permeability and high light-harvesting capacity.

Different shape of bismuth sulfide (Bi2S3), including nanoparticles, and urchin-like, microspheres hierarchical nanostructures, have been successfully fabricated using a facile and template-free solvothermal method. Their crystal and porous structures, morphologies, as well as the optical absorption were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflection spectroscopy (DRS) and nitrogen sorption. The electron microscopy observations showed that both the sulfur sources and solvents greatly affected the morphologies of the as-prepared Bi2S3. Compared with Bi2S3 nanoparticles, the hierarchical architectures exhibited higher activity for photocatalytic reduction of CO2 to methyl formate (MF) in methanol, and Bi2S3 microspheres showed the highest activity. This was attributed to their special hierarchical structure, good permeability and high light-harvesting capacity.