Ultrafine Co2O3powder was prepared via hydrothermal synthesis. The effect of technology on the performance of the superfine Co2O3powders was investigated, and the hydrothermal parameters in preparing Co2O3were gradually improved. In addition, the morphology and grain size of the Co2O3powder were analyzed by FESEM. Results show that reducing the salt–alkali molar ratio resulted in more uniform Co2O3powder and smaller particles, with average particle size of approximately 40 nm. Reaction time displayed little effect on the Co2O3powder, but the particle size decreased with the reaction time. The concentration of salt solution remarkably affected the morphology of the Co2O3powder. Lower concentration resulted in smaller particle aggregation and particle size.

This work investigated the effects of molar ratio of salt to alkali on the properties of tin oxide nanofilms to provide reference for optimizing its photoelectric conversion efficiency. The tin oxide film grown by hydrothermal method exhibited poor film-forming property. The macroscopic analysis revealed the formation of a thick film. The bonding force to the FTO substrate was poor, its brittle, and easy to fall off. When the molar ratio of salt to alkali was 1:8, the tin oxide film exhibited improved microstructure and large specific surface area, which could benefit electron transport. Moreover, the film showed excellent photoelectric conversion performance. However, mechanical properties, such as adhesion between the tin oxide film and the conductive glass FTO, remain to be improved.