RESUMO
In this study, a method was developed to create oxygen vacancies in Cu2O/TiO2 heterojunctions. By varying the amounts of ethylenediaminetetraacetic acid (EDTA), sodium citrate, and copper acetate, Cu2O/TiO2 with different Cu ratios were synthesized. Tests on CO2 photocatalytic reduction revealed that Cu2O/TiO2's performance is influenced by Cu content. The ideal Cu mass fraction in Cu2O/TiO2, determined by inductively coupled plasma (ICP), is between 0.075% and 0.55%, with the highest CO yield being 10.22 µmol g-1 h-1, significantly surpassing pure TiO2. High-resolution transmission electron microscopy and electron paramagnetic resonance studies showed optimal oxygen vacancy in the most effective heterojunction. Density functional theory (DFT) calculations indicated a 0.088 eV lower energy barrier for ∗CO2 to ∗COOH conversion in Cu2O/TiO2 with oxygen vacancy compared to TiO2, suggesting that oxygen vacancies enhance photocatalytic activity.
RESUMO
In this paper, for the first time a simple batch process was utilized for the facile synthesis of cubic FeS(2) and flower-like FeSe(2). By adjusting the amount of solvents and surfactants added, pure pyrite FeS(2) with a defined crystalline structure was obtained. It was found that the reaction temperatures and iron sources had significant influence on the purities and morphologies of FeS(2) and FeSe(2) particles. Raman spectra of the FeS(2) and FeSe(2) samples presented characteristic peaks of S-S and Se-Se active modes at 337, 372 cm(-1), and 180, 217, 254 cm(-1), respectively. The absorption properties of the FeS(2) and FeSe(2) samples were also investigated and the results demonstrated that these samples had broad optical absorption in NIR. Moreover, the synthetic approach demonstrated here may be of great potential for the controlled synthesis of other metal chalcogenides.
