Correlation of photocatalytic activity and defects generated in Ca2+-based heterojunctions

Abstract

In this work a new semiconductor based on calcium heterojunction (CaO/CaTiO 3 ) was evaluated to the optical properties correlated to crystalline lattice defects. The heterojunctions of the semiconductor were prepared by the sol-gel route and its formation was confirmed by the intimate contact interface between crystalline phases. Morphology and elemental composition of the nanometric heterojunction were evaluated. Chemical environment and composition of the surface were used to determine the oxidation state of the material constituents. The electronic structure was evaluated and the relationship among band gap energy, photoluminescent emission energy, and photocatalytic activity of the materials was demonstrated. Oxygen vacancies located on the surface promoted photoluminescent spectra emission in the green wavelength, making them more photoactive than those defects that emitted in the red region. The use of active species scavenger indicated that the photogenerated species with the greatest photocatalytic action was the superoxide radical. This study has developed calcium heterojunctions for application as photocatalysts, demonstrating the importance of the defects generated in the production of heterojunctions and the activity of photogenerated species, studied using scavengers.

Synthesis of Al/starch co-doped in CaO nanoparticles for enhanced catalytic and antimicrobial activities: experimental and DFT approaches

“…The emission peak of CaO and St was observed at 411 nm, which exhibited the direct transition (band-to-band) produced by an electron-hole recombination that occurred at different E g regions. 41 Additionally, when Al and St were added to a pure material, a slight blue-shi to 409 nm occurred and the intensity decreased in contrast to CaO. The decrease in the PL intensity of Al/St-doped CaO is attributed to the minimum exciton recombination, which is suitable for CA.…”