Visible photoluminescence of polyoxoniobates in aqueous solution and their high electrocatalytic activities for water oxidation

Abstract

ABSTRACT14− was observed, and its origin was revealed in the view of molecular orbital by means of the computational method. The photoluminescence is originated from singlet transitions, and the calculated values agree well with the experimental data. The results indicate that the size of clusters and the foreigner atoms can affect the fluorescent properties of PONbs. The absorption and emission of these PONbs are originated molecular orbitals contributed mainly by μ 2 -O and Nb atoms according to NBO analysis. These PONbs were also found as electrochemical catalysts with high performance for water oxidation, which can effectively split water into oxygen under basic condition with a high catalytic current, and pH values have remarkable influence on the electrocatalytic activities of these PONbs for water oxidation.

Toward Exploiting the Behavior of Niobium-Containing Mesoporous Silicates vs. Polyoxometalates in Catalysis

“…It was found that the calculated values are in a good agreement with the experimental data. The obtained results proved also the impact of clusters size and addenda atoms on the catalytic and fluorescent properties of PONbs (Ye et al, 2013 ).…”

Room Temperature Synthesis, Crystal Structure, Water Sorption, and Thermal and Electronic Properties of {[Cu(phen)]2[Cu(phen)2]2Nb6O19}·24H2O

“…Paramagnetic Cu­(II) ions are renowned for their quenching effect on intraligand π L * → π L transitions and the resulting fluorescence of surrounding fluorophores through electron and energy transfers. , However, in Cu­(II) complexes with phen ligands with 5-fold coordination geometry intermediate between trigonal bipyramidal and square pyramidal, an emission could be observed. , Compound I was excited with UV light (λ ex = 275 nm), leading to a luminescence spectrum (Figure S11) with broad emission signals at 386 and 408 nm. These signals are slightly shifted to higher values in comparison to literature data but could be assigned to the phen ligand as π L * → π L transitions. ,, The shoulder at 461 nm might be caused by the hexaniobate unit, which contributes with HOMO to LUMO transitions showing broad signals at around 400 nm upon irradiation with λ ex = 294 nm . A shift to higher wavelength is in some cases observed when polyoxoniobates are connected to Cu­(II) complexes with phen ligands. , The emission signal at 650 nm corresponds to red light, which could be observed as a faint glow during the measurement.…”

“…35,87,90 The shoulder at 461 nm might be caused by the hexaniobate unit, which contributes with HOMO to LUMO transitions showing broad signals at around 400 nm upon irradiation with λ ex = 294 nm. 97 A shift to higher wavelength is in some cases observed when polyoxoniobates are connected to Cu(II) complexes with phen ligands. 46,47 The emission signal at 650 nm corresponds to red light, which could be observed as a faint glow during the measurement.…”

Application of group V polyoxometalate as an efficient base catalyst: a case study of decaniobate clusters

“…Then, we applied (TMA) 6 [Nb 10 O 28 ]$6H 2 O as homogeneous catalyst for aldol-type condensation reactions such as Knoevenagel and Claisen-Schmidt condensation reactions and revealed for the rst time that it acted as a Brønsted base catalyst whose strength is comparable to superbases. This result will open up a new possibility of application of PONbs since their catalytic application has been limited to electrocatalysts 13 and photocatalysts so far. [14][15][16][17]…”