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Electronic structure and optical properties of Ln(III) nitrate adducts with 1,10-phenanthroline
摘要： Adducts of tris-nitrates of rare-earth elements Ce(III), Nd(III), Eu(III), and Er(III) with two molecules of 1,10-phenanthroline with formula Ln(NO3)3(Phen)2 are studied by X-ray photoelectron spectroscopy (XPS) and quantum chemistry (DFT/TDDFT). The geometric structure for DFT modeling is build using X-ray diffraction data. To analyze the composition and differences of the electronic structure in the series under study, XPS spectra were obtained for which interpretation was performed using calculated data. It has been shown that the molecule of Phen, when attached to the complexes of nitrates, is polarized, leads to an increase in absorption in the visible region and reduces the energy gap between HOMO and LUMO. Experimental absorption spectra were obtained, described and interpreted using TDDFT simulation. The transitions in adducts from π to π * MO in Phen ligands determine the main absorption band. The reasons for the absence of luminescence in adducts with ions Ce(III), Nd(III), and Er(III) are revealed by the example of the correlation diagram of singlet and triplet levels. A possible origin of coloring of adducts is determined using TDDFT.
关键词： Optical properties,Nitrates,DFT,Lanthanide ions,Photoelectron spectroscopy
更新于2025-09-19 17:15:36
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Effect of NO2 and NO3-/HNO3 adsorption on no photocatalytic conversion
摘要： A study was undertaken of the adsorption and photocatalytic conversion of NO, NO2 and NO3-/HNO3 using two photocatalysts (P25 and HT-ET). The HT-ET is a catalyst synthesized in our laboratory comprised only of anatase phase and with a surface area three times larger than that of the P25. In powder form, the catalyst was introduced into and extended along the length of a tube with no type of compaction on the part of the solid (pressure drops are negligible under these conditions). This tubular photoreactor arrangement operates as a continuous reactor system enabling FTIR analysis of the surface of the catalysts during the conversion process. NO adsorption was negligible, though the FTIR studies revealed the formation of nitrites on the surface after 18 h of reaction. Overall NO conversion efficiency rates were above 68% with both catalysts in that reaction time. However, selectivity to NO2 was very high with both catalysts. It was also found with both catalysts that the number of NOx moles eliminated during NO photocatalytic conversion coincided with the number of adsorbed NO2 moles observed in the adsorption studies performed with this molecule, indicating that the NO2 molecule is not efficiently converted photocatalytically. It was observed that most of the NO2 undergoes disproportionation on the surface of the catalysts, giving rise to nitrates and NO. The FTIR studies showed that a significant proportion of the NO2 interacts with surface nitrates resulting in [(NO3-)-(H2O) n-NO2] complexes which are stable on the catalyst surface in an NO atmosphere.
关键词： NO2,TiO2,NOx,Photocatalysis,Nitrates,FTIR,NO
更新于2025-09-09 09:28:46